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Aircraft Fuel Characteristics & Storage: Maintenance Training Manual
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For Training Purpose Only DETAILED TRAINING VAR Part 7 – Aircraft Maintenance Basic Cat B TRAINING MANUAL ATA 28 Issue: 01 Rev: 00 Date: 25/04/2014 © VAECO Training Center FUNDAMENTALS ATA 28 FUEL CHARACTERISTICS TYPES OF TURBINE ENGINE FUEL Turbine engine fuels used for jet engines are kerosene type fuels which are closely related to diesel gasoline. There are 4 main types of turbine engine fuel. These are called Jet A1, Jet A, Jet B and JP 5. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 01|Types of Fuel/A/B1 Page 2 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 1 HAM US/F SwD 01.12.2007 Types of Engines Fuel 01|Types of Fuel/A/B1 Page 3 FUNDAMENTALS ATA 28 types of turbine engine fuel cont. The fuel types differ in their main characteristics. Jet A1 is the most commonly used fuel type for jet engines in europe. This fuel type is reasonably safe for you to handle because it has a high flash point of plus 38° C and a low freezing point of minus 47° C. The american name for this type of fuel is JP 1A. Jet A is the most commonly used fuel type for jet engines in america. It is very similar to Jet A1 with the same high flash point of plus 38° C but with a lower freezing point of -40° C. In the USA this fuel is also called JP 1. Jet B fuel is mainly used for military jet engines. Theoretically, it can also be used for civil aircraft engines but Jet B has an extremely low flash point of minus 20° C to provide good ignition capabilities. This means it requires extreme care in handling. Jet B has a very low freezing point of minus 60° C. The atmerican name for this type of fuel is JP 4. JP 5 is another type of military jet fuel. It is preferred by the military on aircraft carriers because its very high flash point of plus 65° C makes it very safe for handling. JP 5 has a relatively low freezing point of minus 48° C. You must record the type of fuel used when refueling. This is important, because each type of fuel has different handling and operating characteristics. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 02|Types of Fuel/A/B1 Page 4 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 2 HAM US/F SwD 01.12.2007 Fuel Main Caracteristics 02|Types of Fuel/A/B1 Page 5 FUNDAMENTALS ATA 28 CHARACTERISTICS OF TURBINE ENGINE FUELS The main requirements of turbine engine fuels are a low freezing point and a flash point low enough to provide good ignition capabilities but as high as possible for safe fuel handling. Turbine engine fuels must also have a low tendency to vaporize in high flight altitudes. Engine fuels need to be widely available all over the world and must have a low tendency to carry water. Different fuels have different freezing points depending on their composition. The freezing point is the temperature at which some elements of the fuel start to crystallize and the fuel flow slows down. The required freezing point of fuel for turbine engines should be below minus 40° Celsius. The flash point of fuel is the lowest temperature at which the fuel creates just enough vapors to build up a fuel/air mixture that can be inflamed. To reduce any fire hazards, the flash point of the fuel used for civil aircraft should be as high as possible. If the flash point is reached, the fuel/air mixture burns, but if the external flame is removed, the fuel/air mixture extinguishes. The volatility is another very important characteristic of jet fuels. Volatility of fuel is its ability to vaporize. A highly volatile fuel is very desirable for engine starts in cold weather and in flight, and fuel with low volatility is desired to eliminate vapor lock and to reduce fuel losses by evaporation. Jet fuel, like all other fluids vaporizes if the ambient pressures decreases. The higher you fly the more the ambient pressure decreases. Ambient pressure decrease causes fuel to vaporize. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 03|Characteristics of Fuels/A/B1 Page 6 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 3 HAM US/F SwD 01.12.2007 Fuel Characteristic 03|Characteristics of Fuels/A/B1 Page 7 FUNDAMENTALS ATA 28 characteristics of turbine engine fuels cont. Another very important characteristic of fuel is its density. This is the ratio between mass and volume. This ratio changes with the fuel type and fuel temperature. Jet A1 and Jet A have the same density of 0.81kg/ltr. at a temperature of 15 C. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 04|Characteristics of Fuels/A/B1 Page 8 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 4 HAM US/F SwD 01.12.2007 Fuel Density 04|Characteristics of Fuels/A/B1 Page 9 FUNDAMENTALS ATA 28 characteristics of turbine engine fuels cont. Other requirements on jet engine fuels are that it must be readily available so that the airlines can get the same fuel type all over the world. It must have adequate lubrication capabilities for the moving parts in the fuel system, and the fuel must have a low tendency to hold water to minimize water contamination problems. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 05|Fuel Requirements/A/B1 Page 10 Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS FUNDAMENTALS ATA 28 Main requirements for turbine engine fuel: low freezing point flashpoint − low enough for ignition − as high as pssible for safe handling low tendency to vaporize in high altitudes low tendency to carry water high volatility desirable for engine starts available all over the world low tendency to hold water FOR TRAINING PURPOSES ONLY! adequate lubrication capabilities water Figure 5 HAM US/F SwD 01.12.2007 Fuel Requirements 05|Fuel Requirements/A/B1 Page 11 FUNDAMENTALS ATA 28 WATER IN FUEL Because jet engine fuels are heavy they tend to carry contamination such as water, dirt or microorganisms. Dirt can be avoided and removed sufficiently by filters, but you will always find some water in fuel. Fuel can carry water in two different conditions. Water may be either dissolved in fuel and, therefore, be totally invisible or it can be suspended in fuel. It is then generally visible as small droplets or water bubbles. Water in fuel must be removed periodically from the tanks, because it can create severe problems in the aircraft fuel system. Water encourages ice build−up if fuel cools down below 0° C. It supports corrosion in the fuel system components and large amounts of water in fuel can cause engine power fluctuations or flame outs. Water accumulations in the fuel tanks will always cause erratic fuel quantity indications. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 06|Water in Fuel/B1 Page 12 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 6 HAM US/F SwD 01.12.2007 Water in Fuel 06|Water in Fuel/B1 Page 13 FUNDAMENTALS ATA 28 water in fuel cont. Another serious problem of water in fuel is that it can support microbial growth in the tanks. These microorganisms are fungus type organisms which live in the layer between fuel and water. They will grow and spread over tank floors and walls and damage the tank sealers and tank structures. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 07|Water in Fuel/B1 Page 14 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 7 HAM US/F SwD 01.12.2007 Microbial Growth 07|Water in Fuel/B1 Page 15 FUNDAMENTALS ATA 28 water in fuel cont. To avoid all the problems of water in fuel, the airline maintenance and fuel suppliers closely monitor the water concentration in fuel and remove the water periodically. Visible water can be easily checked as described next, but what do we do with dissolved water? Suspended water in fuel may be in such small droplets, that it is hardly visible at all. This can give fuel a milky appearance. To clearly determine this kind of water in the fuel, the fuel suppliers have developed several different methods. The most common method to check for this water is by using a syringe test cartridge. You draw fuel off into the cartridge through a chemically treated filter. If the filter changes color the fuel contains water. You then have to wait long enough for the water to settle down and drain it afterwards. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS HAM US/F SwD 01.12.2007 08|Water in Fuel/B1 Page 16 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL CHARACTERISTICS Figure 8 HAM US/F SwD 01.12.2007 Water Concentration Monitoring 08|Water in Fuel/B1 Page 17 FUNDAMENTALS ATA 28 FUEL STORAGE SYSTEM TANK ARRANGEMENT The fuel storage system consists of fuel tanks, the tank drain system and the tank vent system. Normally you find fuel tanks located in the aircraft wings. To increase the range of an aircraft you will also find fuel tanks in the fuselage center section between the wings and sometimes aircraft have additional tanks in the horizontal stabilizer or in the cargo compartment. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 01|Tank Arrangement/A/B1 Page 18 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 9 HAM US/F SwD 01.12.2007 Tank Location 01|Tank Arrangement/A/B1 Page 19 FUNDAMENTALS ATA 28 Tank arrangement cont. On the aircraft shown here the 4 main tanks are the tanks which feed each of the 4 engines. Reserve tanks are used to store the reserve fuel. Note that all aircraft must have space for reserve fuel, but they don’t always have dedicated tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 02|Tank Arrangement/A/B1 Page 20 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 10 HAM US/F SwD 01.12.2007 Main Tanks - Reserve Tanks 02|Tank Arrangement/A/B1 Page 21 FUNDAMENTALS ATA 28 Tank arrangement cont. Auxiliary fuel tanks are optional tanks installed in the cargo compartments to further increase the aircraft range. They are usually removable. Some tanks are called trim tanks because as well as storing fuel, they are also used to trim the aircraft. There are special cavities in the wing tips called vent surge tanks. These tanks are used to make sure the fuel tanks are properly vented. Another way of naming tanks is by location. On this example the tanks are called the wing tanks, center tank and stabilizer tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 03|Tank Arrangement/A/B1 Page 22 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 11 HAM US/F SwD 01.12.2007 Tank Location 03|Tank Arrangement/A/B1 Page 23 FUNDAMENTALS ATA 28 TANK TYPES The most common types of fuel tank on a modern jet aircraft is the integral tank. Integral tanks save weight because parts of the aircraft structure are used as tank walls. You find this type of tank in the wings, in the fuselage center section and in the horizontal stabilizer. This enlarged picture shows a simplified wing structure. Sealed wing ribs are used as divider walls between different tanks. The wing rear spar serves as the rear wall of the tank. The wing front spar serves as the forward wall of the tank. The upper wing skin forms the upper wall of the tank. The lower wing skin forms the lower wall of the tan. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 04|Tank Types/A/B1 Page 24 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 12 HAM US/F SwD 01.12.2007 Integral Tank 04|Tank Types/A/B1 Page 25 FUNDAMENTALS ATA 28 tank types cont. The center tank is formed by the forward, aft, upper and lower walls and by the right and left hand wing ribs. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 05|Tank Types/A/B1 Page 26 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 13 HAM US/F SwD 01.12.2007 Center Tank 05|Tank Types/A/B1 Page 27 FUNDAMENTALS ATA 28 tank types cont. Integral tanks are not leak tight without sealing. Here we see how the parts of the plane are fixed together with rivets or bolts to form an integral fuel tank. A fillet seal is used where 2 plates join, and a cap seal is used to cover a nut or a bolt. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 06|Tank Types/A/B1 Page 28 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 14 HAM US/F SwD 01.12.2007 Integral Tank 06|Tank Types/A/B1 Page 29 FUNDAMENTALS ATA 28 tank types cont. Auxiliary fuel tanks are normally removable. They are not formed by the aircraft structure and require separate tank walls. They are made of a light metal alloy container serving as an outer housing for a flexible rubber bladder, which forms the fuel tank. These type of tanks are called bladder type fuel tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 07|Tank Types/A/B1 Page 30 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 15 HAM US/F SwD 01.12.2007 Additinonal or Auxiliary Tank 07|Tank Types/A/B1 Page 31 FUNDAMENTALS ATA 28 FUEL MOVEMENT DAMPENING Fuel should not be allowed to splash around inside a fuel tank during attitude changes as this would make the aircraft unstable. Dampening devices must be used in the wing tanks to prevent this sort of fuel movement. The ribs in the wing and non−sealed divider walls in the center tank do a lot to dampen fuel movement. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 08|Fuel Movem. Dampg/B1 Page 32 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 16 HAM US/F SwD 01.12.2007 Dampening Devices 08|Fuel Movem. Dampg/B1 Page 33 FUNDAMENTALS ATA 28 fuel movement dampening cont. Fuel splashing around is not the only danger during aircraft attitude changes. If the tank boost pumps run dry, fuel supply to the engines is interrupted and the engines will stop. The flap baffle check valves, which allow fuel movement in 1 direction only, ensure that there is enough fuel for the fuel boost pumps by preventing fuel flow out of the collector boxes. The baffle valves are located along the entire length of these ribs. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 09|Fuel Movem. Dampg/B1 Page 34 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 17 HAM US/F SwD 01.12.2007 Flap/Baffle Valves 09|Fuel Movem. Dampg/B1 Page 35 FUNDAMENTALS ATA 28 fuel movement dampening cont. With the wing up the baffle valves open allowing the collector boxes to have the most fuel. With the wing level the collector boxes, on the lowest part of the tank have a good head of fuel. With the wing down the baffle valves close to retain sufficient fuel in the collector boxes. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 10|Fuel Movem. Dampg/B1 Page 36 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 18 HAM US/F SwD 01.12.2007 Wing Postion 10|Fuel Movem. Dampg/B1 Page 37 FUNDAMENTALS ATA 28 ACCESS TO FUEL TANKS Getting into a fuel tank or being able to look into a fuel tank is a design requirement of all fuel tanks. You can get into a fuel tank through these tank access panels. These access panels are arranged according to the internal structure of the wing to make sure you can get access to all areas of the tank. If a fuel tank is large enough for someone to climb in, then it is usually fitted with internal openings. Internal openings make sense as they reduce the number of external panels and therefore the number of potential leak points. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 11|Access to Tanks/A/B1 Page 38 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 19 HAM US/F SwD 01.12.2007 Tank Access 11|Access to Tanks/A/B1 Page 39 FUNDAMENTALS ATA 28 TANK ACCESS PANELS The access panels allow you to enter a fuel tank. These panels are put together to prevent fuel leaking out. Here you see an exploded view of how an access panel is constructed. The knit aluminium gasket provides metal contact between the access door and aircraft structure to prevent sparks caused by static charges. The clamp ring connects the access door to the wing structure and ensures that the mounting screw forces are equally distributed onto the access panel seals. The mounting screws connects the clamp ring and access door to the wing structure. The floating insert serves as the nut for the mounting screw. The molded rubber seal ensures proper sealing between the access door and the aircraft structure. Remember that if the access panel is replaced and you have carried out the correct torquing sequence you must test the fuel tank for leaks by filling it with fuel. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 12|Access Panel/B1 Page 40 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 20 HAM US/F SwD 01.12.2007 Tank Access Panel 12|Access Panel/B1 Page 41 FUNDAMENTALS ATA 28 FUEL TANK VENTILATION SYSTEM On some aircraft you may find a fuel tank ventilation system, that protects the aircraft and passengers against dangerous fuel leaks. Tanks in critical areas are ventilated. For example, the center tank that sits below the cabin floor, but above the air conditioning compartment needs ventilation. Ventilation is achieved by passing air around the fuel tank, then releasing this air to atmosphere carrying away fuel leaks and vapor. A continuous flow of air is provided around the fuel tank. For the center tank the air is forced through the vapor seal by the cabin pressure. For ventilating the stabilizer tank, ram air is used. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 13|Fuel Tank Ventilation Syst/B1 Page 42 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 21 HAM US/F SwD 01.12.2007 Ventilation System 13|Fuel Tank Ventilation Syst/B1 Page 43 FUNDAMENTALS ATA 28 fuel tank ventilation system cont. The fuel tanks within the fuselage have vapour seals below the tank floor. The space between the tank floor and the vapor seal will be drained and ventilated. Route taken by ventilation air: The ventilation air inlet collects the air which is used for ventilation. The leak monitor collects any fuel leaks from the center tank. The leak monitor is a spur pipe connected to the drain valve. It is used to discover if there has been a leak or not. The air distribution pipes drain or ventilate leakages to the system outlets. The drain mast drains fluids away from the fuselage surface. The fluid exits the aircraft with the aid of pressurized air. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM HAM US/F SwD 01.12.2007 14|Fuel Tank Ventilation Syst/B1 Page 44 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL STORAGE SYSTEM Figure 22 HAM US/F SwD 01.12.2007 Fue Tank Ventilation 14|Fuel Tank Ventilation Syst/B1 Page 45 FUNDAMENTALS ATA 28 FUEL TANK DRAINING WATER DRAINING The main purpose of a tank drain system is to drain water from the fuel tanks. It is also used for emptying a tank to gain access to it. Water and/or fuel is drained from external valves located at the low points of all fuel tanks. Water must be drained from fuel tanks periodically. This prevents all the problems of water in fuel which were described in the lesson about fuel characteristics. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 01|Water Draining/A/B1 Page 46 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 23 HAM US/F SwD 01.12.2007 Water Draining 01|Water Draining/A/B1 Page 47 FUNDAMENTALS ATA 28 water draining cont. A drain tool equipped with a funnel on top and a probe inside is used on the drain valve. When the probe is located in the valve the mechanic pushes the valve open to release the fluid into the bottle. There are 2 types of drain valve, namely direct drain valves and indirect drain valves A tank drain valve that is installed at the lowest point of a tank is called a direct drain valve. Due to design constraints or safety requirements some drain valves are not at the lowest point of a fuel tank. They are called indirect drain valves. On these valves a drain line runs from the lowest point in the fuel tank to the valve housing. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 02|Water Draining/A/B1 Page 48 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 24 HAM US/F SwD 01.12.2007 Drain Valves 02|Water Draining/A/B1 Page 49 FUNDAMENTALS ATA 28 MANUALLY OPERATED DRAIN VALVES For safety reasons the drain valves are normally operated manually. Here we see a cut away drawing of a drain valve. It generally consists of the valve piston and an internal check valve. Note that the piston and the check valve are closed by springs. When the drain tool is inserted into the drain valve, you must push against the spring forces. If you push the piston it first rests on the check valve. With a further push you can lift the check valve too. This opens the check valve and any liquid can be drained. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 03|Manual Drain Valves/B1 Page 50 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 25 HAM US/F SwD 01.12.2007 Manually Drain Valve 03|Manual Drain Valves/B1 Page 51 FUNDAMENTALS ATA 28 manually operated drain valves cont. This is a direct drain valve. The principle of operation is the same. The piston is raised until it reaches the check valve. Then, with another push the check valve is raised and the liquid drains away. You will now understand that even without the outer valve assembly the direct or indirect drain valve should still prevent any liquid draining. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 04|Manual Drain Valves/B1 Page 52 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 26 HAM US/F SwD 01.12.2007 Direct Drain Valve 04|Manual Drain Valves/B1 Page 53 FUNDAMENTALS ATA 28 ELECTRICALLY OPERATED DRAIN VALVES Some drain valves are located in difficult positions, such as these, and can be opened electrically. In the stabilizer tank on this particular aircraft there are 2 electrical sump drain valves. Each is connected via tubes and flexible hoses to a drain hole on the lower fuselage. This ensures that no fluids are spilled into the stabilizer compartment. Electrically operated drain valves rely on a solenoid which opens the valve when activated. Each valve has a manual override button which is used if the solenoid fails to open. The electrical drain valves are controlled by a sump drain control panel located in the stabilizer compartment. On this panel you will find switches to activate the drain valves. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 05|Electrical Drain Valves/B1 Page 54 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 27 HAM US/F SwD 01.12.2007 Electricallay Operated Drain Valves 05|Electrical Drain Valves/B1 Page 55 FUNDAMENTALS ATA 28 WATER SCAVENGE SYSTEM In addition to drain valves, water scavenge systems are used to remove water collected in the tank. Water scavenge systems are installed in very big fuel tanks where large quantities of water can be expected. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 06|Water Scavenge System/B1 Page 56 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 28 HAM US/F SwD 01.12.2007 Water Scavenge System 06|Water Scavenge System/B1 Page 57 FUNDAMENTALS ATA 28 water scavenge system cont. This shows the water scavenge system of the main tank no.1. Water scavenge systems remove water from the tank by means of the fuel tank boost pumps. Most of this fuel goes to the engines but some goes to the jet pump, which gets sprayed back into the boost pump inlet. Suction is created at the jet pump inlet, which is at the lowest point in the fuel tank. Water or fuel is sucked into the jet pump, mixed with the fuel from the boost pump and sprayed back into the boost pump inlet. The jet pump operates without electrical power and is therefore explosion proof. Scavenge systems are normally driven by jet pumps. But they can just as easily be driven by electrical pumps as you will see later in this unit. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 07|Water Scavenge System/B1 Page 58 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 29 HAM US/F SwD 01.12.2007 Water Scavenge Sytem 07|Water Scavenge System/B1 Page 59 FUNDAMENTALS ATA 28 FUEL DRAINING To gain access to a fuel tank, the tank must first be emptied. Defueling removes most of the fuel, but there is always a little left. So to drain this last part of fuel in a tank, the water drain valve is used. A special drain purging tool is used to remove large quantities of fuel from any tank. The tool is pushed into the drain valve and locked in place. The fuel is normally drained by gravity. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING HAM US/F SwD 01.12.2007 08|Duel Draining/A/B1 Page 60 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK DRAINING Figure 30 HAM US/F SwD 01.12.2007 Fuel Drain Valve 08|Duel Draining/A/B1 Page 61 FUNDAMENTALS ATA 28 FUEL TANK VENT SYSTEM FUEL TANK VENT SYSTEM INTRODUCTION The purpose of a fuel tank vent system is to allow air in the fuel tanks to escape during refueling, and to allow air to enter the tanks in flight when the fuel is being used. This protects the tanks against overpressure and negative pressure. All fuel tanks are connected by vent lines to the vent surge tanks. These tanks are open to the atmosphere. During flight ram air is used to reduce the tendency for the fuel to vaporize at high altitudes, by creating a small positive air pressure on top of the fuel surface inside the tanks. Notice that each tank has a vent pipe out to a vent tank. The exception is the auxiliary tank, if one is fitted. It will be vented via another fuel tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 01|Introduction/A/B1 Page 62 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 31 HAM US/F SwD 01.12.2007 Fuel Tank Vent System 01|Introduction/A/B1 Page 63 FUNDAMENTALS ATA 28 FUEL TANK VENT SYSTEM OVERVIEW The center tank is vented via ducts to the vent surge tanks at the end of each wing. The inner main tanks vent to the vent surge tank along 2 independent vent ducts. The outer main tanks vent via 1 duct to the vent surge tank. The reserve tanks vent independently to the vent surge tank. The vent surge tanks vent all the air from the connected fuel tanks to the atmosphere. The vent ducts are very often tubes running through the wing. To save weight another design is used. Here some wing stringers which are normally z−profiles are arranged in such a way that they form u−shaped vent ducts with the upper wing skin. Note, large tanks may have 2 vent ducts to ensure proper venting at high refueling rates. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 02|Vent System Overview/A/B1 Page 64 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 32 HAM US/F SwD 01.12.2007 Tank Vent System 02|Vent System Overview/A/B1 Page 65 FUNDAMENTALS ATA 28 FUEL TANK VENT SYSTEM OPERATION If, during maneuvers, fuel enters the vent duct via the open ports, it can drain back into the tank through the drain valve instead of ending up in the surge tank. Another way to do this job is with a rubber check valve. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 03|Vent System Ops/B1 Page 66 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 33 HAM US/F SwD 01.12.2007 Fuel Interacts during Maneuvers 03|Vent System Ops/B1 Page 67 FUNDAMENTALS ATA 28 fuel tank vent system operation cont. The fuel moves to the inboard side of the tank and enters the open port, flooding the stand pipe. The tank is now vented through the open float valves. Any fuel caught in the vent duct which entered through the open port is drained back into the tank. The fuel moves to the outboard side of the tank. The float valves close. The tank is vented through the open port. We have seen how the fuel tanks vent. They are all connected to the vent surge tank. Each tank vents individually so that there is no interconnection between the tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 04|Vent System Ops/B1 Page 68 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 34 HAM US/F SwD 01.12.2007 Fuel Interacts via Wing Up/Down 04|Vent System Ops/B1 Page 69 FUNDAMENTALS ATA 28 fuel tank vent system operation cont. Inside the vent surge tank you will find the NACA intake and overpressure relief valves. In the vent duct from the NACA intake to the stand pipe is a flame arrestor. This prevents flames entering the vent tank. When refueling went wrong and you continue pumping fuel into a tank, fuel enters the vent surge tank and is finally dumped overboard. Some of the fuel remains in the vent tank and it is passed back through drain lines and drain valves to the main tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 05|Vent System Ops/B1 Page 70 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 35 HAM US/F SwD 01.12.2007 Fuel Vent System 05|Vent System Ops/B1 Page 71 FUNDAMENTALS ATA 28 FUEL TANK PRESSURIZATION During flight air is collected by the NACA air inlet. This air is then carried via the vent ducts to the fuel tanks. Here it acts as an air cushion on the fuel which reduces fuel vaporization. The NACA intake provides the opening of the tank vent system to the atmosphere. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 06|Tank Pressurization/B1 Page 72 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 36 HAM US/F SwD 01.12.2007 Fuel Tank Pressurization 06|Tank Pressurization/B1 Page 73 FUNDAMENTALS ATA 28 OVERPRESSURE PROTECTION If a problem develops with the vent system a protection system will prevent any pressure build up in the fuel tanks and the serious damage this would cause. For example if the flame arrestor got blocked the vent system would stop. If a dangerous pressure level is reached pressure relief valves open, preventing the pressure from causing structural damage. These pressure relief valves are generally found in the vent surge tanks, but on some aircraft you may also find them in the wing tanks or in the center tank. These pressure relief valves are either carbon discs, that break at a certain differential pressure or they are spring loaded pressure relief valves that open if the differential pressure overcomes the spring force. Note: In any case these valves will stay open after they are activated. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM HAM US/F SwD 01.12.2007 07|Overpressure Protect/B1 Page 74 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL TANK VENT SYSTEM Figure 37 HAM US/F SwD 01.12.2007 Overpressure/Negative Pressure 07|Overpressure Protect/B1 Page 75 FUNDAMENTALS ATA 28 REFUELING SYSTEM: INTRODUCTION REFUELING METHODS The refueling system of an aircraft consists of pipes, valves, controls and indicators. Refueling panels such as this are used to refuel or defuel the aircraft or to transfer fuel from tank to tank. There are 2 methods of refueling, namely gravity refueling and pressure refueling. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 01|Refuel Methods/A/B1 Page 76 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 38 HAM US/F SwD 01.12.2007 Fueling System/Panel 01|Refuel Methods/A/B1 Page 77 FUNDAMENTALS ATA 28 refueling methods cont. Gravity refueling is done by an external pump and hose into the wing tanks via overwing filler ports. These filler ports are open directly into the wing tanks and do not feed into the pipes of the refueling system. Take care not to drop any objects into the open tanks! Some tanks are not equipped with an external filler port − for example the center tank and stabilizer tank. For these tanks, it is necessary to transfer fuel into them from the main tanks. The main disadvantage of gravity refueling is that it takes so long. It could take about 2 days to gravity refuel a Boeing 747. Other disadvantages for overwing refueling apart from being very slow are, that it is easy to spill some fuel you must always follow the safety precautions for walking on the wing with the fuel tank open; tools may fall into the tank and even if you are careful with your tools and don’t drop them into the fuel tank, other things such as rain, snow and dust may get into the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 02|Refuel Methods/A/B1 Page 78 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 39 HAM US/F SwD 01.12.2007 Gravity Refueling 02|Refuel Methods/A/B1 Page 79 FUNDAMENTALS ATA 28 refueling methods cont. Because of these disadvantages, the normal method to refuel an aircraft is by pressurized refueling either from a fuel tank truck as shown here or by an underfloor fuel supply system. The refueling hose nozzle makes a sealed connection at the refuel couplings, which means that you can pump fuel into the system at about 50 psi. This pressure refueling method is safe, efficient and ensures short turn around times because you can refuel a Boeing 747 in about an hour. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 03|Refuel Methods/A/B1 Page 80 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 40 HAM US/F SwD 01.12.2007 Pressurized Refueling 03|Refuel Methods/A/B1 Page 81 FUNDAMENTALS ATA 28 FUEL DISTRIBUTION The term fuel distribution refers to where the fuel load is placed in the aircraft by the operator or system. You have to make sure that the fuel is correctly distributed to the appropriate tanks. You can do this yourself by controlling the refueling valves or on modern aircraft let a computer do it for you. The correct fuel distribution ensures that the fuel load is balanced. An unbalanced fuel load can cause very dangerous flight conditions. Also on the ground an unbalanced fuel load is not acceptable, particularly on aircraft with stabilizer tanks or additional auxiliary tanks in the aft cargo compartment. Very dangerous conditions can occur. Refueling the stabilizer tank without fuel in the wing or center tanks increases the danger of moving the center of gravity aft of the main landing gear resulting in severe structural damage and a lot of tidying up to do. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 04|Fuel Distribution/A/B1 Page 82 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 41 HAM US/F SwD 01.12.2007 Fuel Load 04|Fuel Distribution/A/B1 Page 83 FUNDAMENTALS ATA 28 fuel distribution cont. The correct distribution of fuel also ensures that the aircraft structure does not get stressed during normal operation. This is important if the aircraft is not completely filled, for example for a short flight. For example it is obvious that high loads are applied on the structure during touch down. As the aircraft lands the weight of the aircraft applies a large downwards force in the center of the fuselage. Any fuel in the center tank would apply a higher than normal downward force in the center of the fuselage resulting in higher stress. Fuel distribution must be managed to prevent an aircraft touch down with a full center tank but empty wing tanks. Remember, that any fuel weight in the outer wing creates a counteracting force on the fuselage at touch down which releases the stress on the wing to fuselage connection. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 05|Fuel Distribution/A/B1 Page 84 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 42 HAM US/F SwD 01.12.2007 Fuel Load / Fuel Weight 05|Fuel Distribution/A/B1 Page 85 FUNDAMENTALS ATA 28 REFUELING SYSTEM ORGANIZATION Here is a complete picture of a refueling system. The main components of any refueling system include: the refueling couplings, which allow you to connect a fueling hose to the aircraft the refueling manifold, which connects the couplings to all the tanks refueling valves, which allow you to control individual refueling to each tank diffusers or also called tank distribution manifolds, which distribute fuel into the tanks the refueling control panel, where you control and monitor refueling and in addition, you will find computers on modern aircraft to control the refueling for you. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 06|Refueling System Organisation/A/B1 Page 86 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 43 HAM US/F SwD 01.12.2007 Refueling System 06|Refueling System Organisation/A/B1 Page 87 FUNDAMENTALS ATA 28 REFUELING MODES There are 3 modes of pressure refueling, namely manual, automatic and override. In manual mode, you must calculate the fuel distribution before refueling. During refueling, you have to monitor the fuel quantities in the tanks as you operate switches on the refueling control panel to open and close the refueling valves. In automatic mode the fuel quantity control computer takes your block fuel preselection and works out the correct distribution. It then controls the refueling valves for correct fuel and distribution. Automatic refueling has the advantage that it is safe, it reduces your workload, and it stops refueling when you reach the preselected block fuel. Therefore it is the normal mode on modern aircraft. Override mode is an alternative procedure if electrical power to the refueling valves is not available. You physically open the refueling valves by a mechanical override on the refueling valves. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION HAM US/F SwD 01.12.2007 07|Refueling Modes/A/B1 Page 88 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM: INTRODUCTION Figure 44 HAM US/F SwD 01.12.2007 Refueling Mode 07|Refueling Modes/A/B1 Page 89 FUNDAMENTALS ATA 28 REFUELING SYSTEM FUNCTION CONTROL PANELS On modern aircraft, refueling control panels can be found at the wing leading edge, usually close to the refueling couplings or on the fuselage, where they can be easily reached without a stand or a ladder or in the cockpit. The external refueling control panel and the cockpit refueling control panel are shown below. As you can see the cockpit control panel offers only limited functions. In fact, only automatic refueling is possible from the cockpit. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 01|Refueling Panels/A/B1 Page 90 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 45 HAM US/F SwD 01.12.2007 Refueling Control Panels 01|Refueling Panels/A/B1 Page 91 FUNDAMENTALS ATA 28 CONTROLS FOR REFUELING The main controls are the refueling valve switches. To activate the switches on this aircraft the switch guard must be opened. In the OPEN position the respective tank refueling valve opens provided that the mode selector is not in OFF. When in the NORM position the refueling valve is controlled by the automatic refueling logic provided that the mode selector is in REFUEL. In the SHUT position the refueling valve closes. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 02|Controls for Refuelg/A/B1 Page 92 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 46 HAM US/F SwD 01.12.2007 Controls for Refueling 02|Controls for Refuelg/A/B1 Page 93 FUNDAMENTALS ATA 28 CONTROLS FOR REFUELING On most modern aircraft you will find a pre−selector which enables the setting of the required block fuel. The pre−selector always displays the amount of fuel that has been preselected. You can adjust this amount using the adjuster. The adjuster is either a rocker switch or on other aircraft it could just as easily be a rotary switch, or a thumb wheel. Once selection has been made, the preselected value must be transmitted to the computer. On most aircraft refueling panels you will find a power switch which controls the refueling system power supply. The switch allows selection of supply by normal electrical power or directly by the battery. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 03|Controls for Refuelg/A/B1 Page 94 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 47 HAM US/F SwD 01.12.2007 Controls for Refueling 03|Controls for Refuelg/A/B1 Page 95 FUNDAMENTALS ATA 28 controls for refueling cont. On an Airbus you use the mode selector switch to activate all the required components for either refueling or defueling the aircraft. When switched to DEFUEL, a light indicates to you that the special transfer valve required for defueling is open. Moving the mode selector switch to the REFUEL position activates the pre−selection. On aircraft that have an additional cockpit refueling panel, you will find the controls that are required to perform automatic refueling. These are the pre selector and switches that activate the preselection and power the refueling control circuits. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 04|Controls for Refuelg/A/B1 Page 96 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 48 HAM US/F SwD 01.12.2007 Refueling on Airbus 04|Controls for Refuelg/A/B1 Page 97 FUNDAMENTALS ATA 28 INDICATIONS FOR REFUELING Typical indications on a refueling panel are the tank quantity indicators. Notice that each fuel tank has its own display. The tank quantity is normally shown as a digital readout in kilograms, but this can be calibrated to pounds if requested by the airline. Additionally, you will find a total fuel quantity indicator that shows the total amount of fuel on the aircraft. On some aircraft you may find refueling valve position lights. On this panel each refueling valve has a blue light which indicates that the valve is open. Also, you may find warnings that show malfunctions in the refueling system. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 05|Indications for Refuelg/A/B1 Page 98 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 49 HAM US/F SwD 01.12.2007 B747 Refueling Indication 05|Indications for Refuelg/A/B1 Page 99 FUNDAMENTALS ATA 28 Indications for refueling cont. On Airbus aircraft, the refueling valve position is not shown. Instead the blue light indicates to you that the respective tank is completely full. When this occurs, the respective refueling valve is closed. There are also some test switches on the refueling panels for you to verify that the system is working properly. Make sure you use them before you start refueling. One test is to see if the quantity system and all its indicators are functioning correctly. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 06|Indications for Refuelg/A/B1 Page 100 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 50 HAM US/F SwD 01.12.2007 Refueling Indication 06|Indications for Refuelg/A/B1 Page 101 FUNDAMENTALS ATA 28 POWER SUPPLY FOR REFUELING Electrical power to the refueling system is normally supplied when the panel door is open. As the panel door opens, a switch is activated and the refueling system is powered up. Normal refueling power supply is provided by external power or the APU via the fueling bus, which is also called the ground handling bus. Alternatively the power can come directly from the battery. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 07|Power for Refuelg/B1 Page 102 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 51 HAM US/F SwD 01.12.2007 Electrical power for Refueling 07|Power for Refuelg/B1 Page 103 FUNDAMENTALS ATA 28 REFUELING MODES To reduce your workload, you normally refuel an aircraft using the automatic mode. You enter the required block fuel on the preselector, activate the automatic mode and then let the system take care of safe balancing, correct distribution and fast refueling. Your preselection is given to the fuel control computer which calculates how much fuel each tank must carry to meet your requirements. The distribution calculation is stored in the fuel control computer and is not shown anywhere on the refueling panel. The calculation for 170,000 kg preselected block fuel results in filling all wing tanks and putting fuel in both center and stabilizer tank. As you can see, with 120,000 Kg of preselected block fuel, the fuel control computer determines not to put any fuel into the stabilizer tank. If you preselect 60,000 Kg, the center tank does not receive any fuel and even the inner wing tanks are not completely filled. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 08|Refuling Modes/A/B1 Page 104 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 52 HAM US/F SwD 01.12.2007 Refueling Mode 08|Refuling Modes/A/B1 Page 105 FUNDAMENTALS ATA 28 refueling modes cont. After the fuel control computer has calculated the fuel distribution, it receives the actual fuel quantity in each tank from the respective fuel quantity probes. It then compares actual tank quantity with calculated quantity and sends open signals to the respective refueling valves. It cuts off the open signals to the respective refueling valves if the calculated quantity is reached. The fuel control computer also sends fuel quantity information to the indicators on the refueling control panel and in the cockpit. In manual refueling mode, you, the mechanic, have to do the distribution calculation; next you select the manual mode on the refueling panel and then you directly operate the refueling valves by switches on the refueling control panel. Remember, that in automatic mode, when the quantity in each tank reaches the calculated value, the fuel control computer closes the refueling valves. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 09|Refueling Modes/A/B1 Page 106 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 53 HAM US/F SwD 01.12.2007 Fuel Control Computer 09|Refueling Modes/A/B1 Page 107 FUNDAMENTALS ATA 28 REFUELING SAFETY SHUT-OFF SYSTEMS Look at this example, here main tank 1 refueling valve has remained energized open. Because any system can fail, refueling systems are equipped with special components and electrical circuits to prevent tank overfilling. Volumetric top−off systems are installed on most Boeing aircraft. These are systems which use the signals from the fuel quantity probes to monitor the fuel levels in the tanks. If the level reaches a pre-set value these systems cut off the power supply to the respective refueling valve. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 10|Refueling Safety System/A/B1 Page 108 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 54 HAM US/F SwD 01.12.2007 Refueling Shut Off System 10|Refueling Safety System/A/B1 Page 109 FUNDAMENTALS ATA 28 refueling safety shut off system cont. On other aircraft, like this A320, overfilling protection is independent of the fuel quantity indication system. High Level Sensors are installed at the high points in the tanks. During refueling these sensors are activated by the increasing fuel level. These sensors cut−off the opening signal to the respective refueling valve and cause it to close. As you can see, these protection systems do not depend on signals from the fuel quantity probes. They work as well if the opening signals do not come from the fuel control computer. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 11|Refueling Safety System/A/B1 Page 110 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 55 HAM US/F SwD 01.12.2007 Refueling Shut Off System (Airbus) 11|Refueling Safety System/A/B1 Page 111 FUNDAMENTALS ATA 28 refueling safety shut off system cont. For further protection, overflow sensors or float switches in the vent tanks detect if fuel over spills from the tanks via the vent ducts. The overflow sensors or float switches in vent tanks provide additional backup to the hi-level systems or top-off systems. If an overspill occurs, the overflow protection circuits can shut off power to all refueling valves or they just trigger a warning. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION HAM US/F SwD 01.12.2007 12|Refueling Safety System/A/B1 Page 112 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING SYSTEM FUNCTION Figure 56 HAM US/F SwD 01.12.2007 Overflow Sensors or Float Switches 12|Refueling Safety System/A/B1 Page 113 FUNDAMENTALS ATA 28 REFUELING COMPONENTS REFUELING COUPLING The main components of a typical refueling system are: the refueling couplings the refueling valves the refueling manifold and the diffusers. The refueling couplings are on the underside of 1 or both wings where you can easily get access. Not all aircraft have the same number of couplings. This Boeing 747, for example has 4 couplings, 2 under each wing. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 01|Refuelg Coupling/B1 Page 114 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 57 HAM US/F SwD 01.12.2007 Refueling System 01|Refuelg Coupling/B1 Page 115 FUNDAMENTALS ATA 28 refueling coupling cont. This A320 has 2 refueling couplings, 1 under each wing. Other aircraft like the Boeing 737 only have 1 refueling coupling. On aircraft with 1 coupling only, they are generally located at the right hand wing. The separate refueling coupling locations give an alternate position to connect the refueling hose if the fuel truck cannot get access to 1 wing. Please note that simultaneous refueling using the couplings on both wings is only allowed on certain aircraft types. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 02|Refuelg Coupling/B1 Page 116 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 58 HAM US/F SwD 01.12.2007 Refueling Couplings 02|Refuelg Coupling/B1 Page 117 FUNDAMENTALS ATA 28 refueling coupling cont. Each refueling coupling has a cap to protect it from damage and dirt, and to make a smooth surface with the wing skin. The refueling coupling incorporates a spring loaded check valve which prevents any fuel leaks. When you connect the refueling nozzle, the internal plunger pushes the check valve open and allows fuel to enter the refueling system. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 03|Refuelg Coupling/B1 Page 118 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 59 HAM US/F SwD 01.12.2007 Refueling Coupling and Nozzle 03|Refuelg Coupling/B1 Page 119 FUNDAMENTALS ATA 28 REFUELING MANIFOLD The refueling manifold is basically a long piece of pipe which is routed through the tanks and connects the refueling couplings to the refueling valves in all tanks. This photo shows a part of the refueling manifold. It comes from the refueling couplings and goes through a wing rib to interconnect all the wing tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 04|Refuelg Manifold/B1 Page 120 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 60 HAM US/F SwD 01.12.2007 Refueling Manifold 04|Refuelg Manifold/B1 Page 121 FUNDAMENTALS ATA 28 refueling manifold cont. During flight, the center tank empties first. Eventually the refueling manifold in the center tank will be above the fuel level. With the manifold full of fuel, it bends more due to the effects of gravity. In particular, this would always create high stresses at touch down. In addition, in flight turbulences cause the manifold to bend up and down. The manifold bending can lead to fatigue in the manifold, resulting in bends, cracks and eventually manifold rupture. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 05|Refuelg Manifold/B1 Page 122 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 61 HAM US/F SwD 01.12.2007 Refueling Manifold Bending 05|Refuelg Manifold/B1 Page 123 FUNDAMENTALS ATA 28 refueling manifold cont. To prevent this damage, manifold drain valves empty the refueling manifold when the fuel level in the tanks falls below the manifold. These drain valves are at the low points of the refueling manifold and are usually installed in the wing tanks near the wall of the center tank. If the refueling manifold is not pressurized, the pressure valve inside the drain valve is spring loaded open but the flapper check valve, held in place by another small spring, prevents any reverse flow of fuel from the tank into the valve and manifold and stops the manifold from emptying if the tanks are full. When pressurized fuel enters the manifold, the pressure valve closes and prevents uncontrolled filling of the wing tanks via this valve. When pressure is released in the manifold after refueling, the spring forces the pressure valve open again. Now fuel can drain into the wing tank if the fuel level drops below the drain valve. To enable proper draining into the wing tanks air release valves allow air into the manifold. These valves are closed during refueling when the manifold is pressurized and they open when the refueling manifold is not pressurized. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 06|Manifold and Valves/B1 Page 124 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 62 HAM US/F SwD 01.12.2007 Fuel Manifold and Valves 06|Manifold and Valves/B1 Page 125 FUNDAMENTALS ATA 28 REFUELING VALVES Refueling valves in each tank control the fuel flow into the tanks during the refuel operations. Originally, on older aircraft, these valves were manually operated or motor driven valves, but now you only find solenoid operated valves. The refueling valves are normally attached to the front or rear spars of the wing tanks and to the rear wall of the center tank. They have their control components outside the tank and the valve components inside the tank. This arrangement of the refueling valves allows the replacement of the control components without emptying the tank and gives you easy access to operate the valve by manual override if necessary. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 07|Refueling Valve/B1 Page 126 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 63 HAM US/F SwD 01.12.2007 Refueling Valves 07|Refueling Valve/B1 Page 127 Lufthansa Technical Training FOR TRAINING PURPOSES ONLY! FUEL SYSTEMS REFUELING COMPONENTS FUNDAMENTALS ATA 28 refueling valves cont. Solenoid operated refueling valves are fail−safe. This graphic shows the cutaway view of a typical solenoid controlled refueling valve. When no electrical power is supplied to the solenoid valve, fuel from the pressurized refueling manifold seeps into the valve chamber through a hole in the valve plate. Pressure builds up in the chamber and acts back upon the larger surface area of the valve plate, sealing it against the valve inlet and keeping the valve plate closed. To open the valve the solenoid is energized by 28 V DC coming from the fuel quantity control computer or directly via the refueling valve switch. When the solenoid is energized, the plug moves to the left. This opens the port in the valve chamber and releases the closing pressure on the valve plate. Once the closing pressure is gone, the plate is pushed open by the pressure in the refueling manifold to allow fuel into the tank. When refueling for that tank is complete, or if you lose electrical power, the solenoid is de−energized and the valve closes. If there is no electrical power available or the valve doesn’t open electrically you can open the refueling valves by a manual override. Some refueling valves have an override plunger which you press and hold to allow fuel into and others have an override screw which opens the refueling valve. Whatever the type of valve, manual override means that you have to be at the valve to open and close it. When you press the override plunger the refueling valve opens to allow fuel into the associated tank. When you press the manual override plunger, it pushes against this sleeve and moves the sleeve and the solenoid plug back to allow pressure to escape from the valve chamber. Once the closing pressure is released, the pressure of fuel in the refueling manifold pushes the valve plate up and fuel can enter the tank. The moment you release the plunger, the sleeve seals off the valve chamber and the valve closes. HAM US/F SwD 01.12.2007 08|Refuelg Vlv Ops/B1 Page 128 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 64 HAM US/F SwD 01.12.2007 Solenoid Controlled Refueling Valve 08|Refuelg Vlv Ops/B1 Page 129 FUNDAMENTALS ATA 28 DIFFUSERS When the refueling valve is open, fuel enters the tank through the diffuser. The diffuser is made up of a perforated tube that allows fuel to exit the manifold. The baffle on top of the diffuser directs the fuel flow downwards. On some aircraft the diffusers are also called tank distribution manifolds. These are long perforated tubes routed close to the tank floor. Diffusers and tank distribution manifolds soften the fuel jet that enters the tank caused by the 50 psi refueling pressure. This prevents damage to internal tank components and reduces fuel foaming. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS HAM US/F SwD 01.12.2007 09|Diffusers/B1 Page 130 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS REFUELING COMPONENTS Figure 65 HAM US/F SwD 01.12.2007 Tank Diffuser 09|Diffusers/B1 Page 131 FUNDAMENTALS ATA 28 FUEL FEED SYSTEM PURPOSE OF FUEL FEED SYSTEM The main purpose of the fuel feed system is to ensure proper fuel supply to the engines and APU. Generally each engine is supplied by a dedicated tank, via the fuel feed manifold. Fuel feed from any tank to any engine is possible via the interconnecting lines. These are also called the cross feed manifolds. Fuel is generally fed to the engines by fuel boost pumps in the tanks. A design requirement of the fuel feed system is that there must be two fuel boost pumps for every consumer, so that if one pump fails it will be immediately backed up by the other one. A further requirement is that a bypass of the boost pumps must be available in case of pump failure. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 01|Intro/A/B1 Page 132 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 66 HAM US/F SwD 01.12.2007 Fuel Feed System 01|Intro/A/B1 Page 133 FUNDAMENTALS ATA 28 fuel feed system: purpose cont. The APU is also a fuel consumer. The APU fuel feed manifold provides the fuel feed to the APU. In this example the fuel comes from the left hand inner tank. The second purpose of the fuel feed system is to enable isolation of any consumer from the system. This is mainly for safety reasons, for example during an engine fire the fuel supply must be cut off. This is done by shut−off valves in the fuel feed lines. A further task of the system is to control the order in which the fuel tanks will be emptied during flight, including the control of the reserve tanks. If the aircraft is equipped with a tank in the horizontal stabilizer, a transfer line feeds the fuel from there to the center tank. On some aircraft you will find optional sub−systems such as a fuel scavenge system. These systems are used to reduce the amount of non usable fuel in the fuel tanks. They are similar to water scavenge systems and are found in tanks where the boost pump inlets are not at the lowest points of the tanks. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 02|Feed System Purpose/A/B1 Page 134 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 67 HAM US/F SwD 01.12.2007 APU, Horizontal Stabilizer and Fuel Feed System 02|Feed System Purpose/A/B1 Page 135 FUNDAMENTALS ATA 28 fuel feed system: purpose cont. Another optional system you may find is the fuel recirculation system. Here fuel is used to cool the integrated drive generator and the engine oil system and then is passed back to the fuel tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 03|Fuel Recirc Syst/B1 Page 136 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 68 HAM US/F SwD 01.12.2007 Fuel Recirculation System 03|Fuel Recirc Syst/B1 Page 137 FUNDAMENTALS ATA 28 FUEL FEED MANAGEMENT The fuel feed system must ensure the correct fuel feed sequence. This means that fuel is used from the tanks in the required sequence. The fuel feed sequence is controlled by switches on the fuel control panel in the cockpit. These switches normally arm the feed system, but feed management itself is achieved in a number of different ways. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 04|Fuel Feed Mngmt/A/B1 Page 138 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 69 HAM US/F SwD 01.12.2007 Fuel Feed Management 04|Fuel Feed Mngmt/A/B1 Page 139 FUNDAMENTALS ATA 28 fuel feed management cont. One method of fuel feed management found on some aircraft such as this Boeing 737, uses different feed pressures. This means that tanks which have pumps with a higher delivery pressure are emptied first. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 05|B737 Feed Mngmt/A/B1 Page 140 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 70 HAM US/F SwD 01.12.2007 Fuel Feed Management B737 05|B737 Feed Mngmt/A/B1 Page 141 FUNDAMENTALS ATA 28 fuel feed management cont. A second method of fuel feed management uses a computer. You find this method on most modern aircraft such as this Boeing 747−400. Finally, a third method of fuel feed management uses a combination of pressure and computer control. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 06|Fuel Feed Mngmt/A/B1 Page 142 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 71 HAM US/F SwD 01.12.2007 Fuel feed Management on B747 or A 320 06|Fuel Feed Mngmt/A/B1 Page 143 Lufthansa Technical Training FOR TRAINING PURPOSES ONLY! FUEL SYSTEMS FUEL FEED SYSTEM FUNDAMENTALS ATA 28 ORGANIZATION OF FUEL FEED SYSTEM Each major tank normally has 2 motor driven fuel boost pumps. They supply the engines and the APU with sufficient fuel and prevent cavitation at the main fuel pumps. Note that each pump must be able to provide sufficient fuel to at least 1 engine at takeoff thrust conditions. The pump discharge check valves prevent reverse flow from the fuel feed manifold back into the fuel tank. This could happen if 1 fuel pump is stronger than the other one. The boost pump bypass suction port enables both boost pumps to be bypassed so that fuel is delivered by gravity or engine suction. The fuel feed manifolds are the fuel lines which supply the engines. The crossfeed manifold interconnects the left hand and right hand tanks and consumers. The engine fuel shut off valves enable isolation of fuel flow to an engine. These valves are also called engine fire shut−off valves or engine low pressure fuel valves. The cross feed valves enable you to feed the left hand engines from the right hand tanks or vice versa. The valves are normally closed, so that each engine is supplied by its dedicated tank. Only twin-engined aircraft just have 1 crossfeed valve, others have more. Sequence valves are pressure relief valves attached to some fuel boost pumps. They reduce the output pressure of these pumps to ensure that fuel from the center tank is used first. Air release valves allow air trapped in the fuel line to bleed out under pump pressure. This prevents air bubbles being ported to the engine which may then interrupt the fuel supply. Fuel transfer valves are used for many different purposes on an aircraft. In the wing tanks they permit fuel transfer from the outer reserve tanks to the inner main tanks. Installed between the feed system and the refueling system, the valve enables fuel transfer into any other tank via the refueling system. HAM US/F SwD 01.12.2007 07|Feed Syst Components/B1 Page 144 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 72 HAM US/F SwD 01.12.2007 Fuel Feed System Main Components 07|Feed Syst Components/B1 Page 145 FUNDAMENTALS ATA 28 fuel feed system: organization cont. Transfer valves in the center tank are used to control fuel feed between the stabilizer tank and the center tank. Because of the long fuel line routed through the fuselage between the center tank and stabilizer tank 1 single line is used for fuel feed and for refueling to reduce potential leaks. For the same safety reasons the transfer valves in the center tank and in the stabilizer tank serve as isolation valves. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 08|Feed Transfer Valves/B1 Page 146 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 73 HAM US/F SwD 01.12.2007 Transfer Valves 08|Feed Transfer Valves/B1 Page 147 FUNDAMENTALS ATA 28 fuel feed system: organization cont. The APU takes its fuel either from a connection on the fuel feed manifold as shown here or on other aircraft, directly from the left hand inner main tank. The APU has its own fuel boost pump which is capable of running on battery power to support an APU start and a fuel isolation valve on its fuel feed line which closes if the APU is not running. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 09|APU Fuel Feed Syst/B1 Page 148 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 74 HAM US/F SwD 01.12.2007 APU Fuel Feed 09|APU Fuel Feed Syst/B1 Page 149 FUNDAMENTALS ATA 28 FUEL MANAGEMENT CONTROL PANEL The controls for the fuel feed system are found on the center overhead panel, within easy reach of both pilots. All the major fuel tanks have 2 boost pumps. Another requirement is that the boost pumps that feed the engines have independent power supply. This means that they have individual control switches and electrical circuits. Power for each pump comes from a separate electrical bus. This is fail safe, because if you loose 1 bus, as shown here, 1 boost pump per tank is still available. The crossfeed valve is activated by its control switch on the fuel control panel. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 10|Fuel Mngmt Contr Panel/A/B1 Page 150 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 75 HAM US/F SwD 01.12.2007 Fuel Management Control 10|Fuel Mngmt Contr Panel/A/B1 Page 151 FUNDAMENTALS ATA 28 fuel management control panel cont. On aircraft equipped with more than 1 crossfeed valve, as in this example, you will find individual switches for each crossfeed valve to enable any combination of fuel feed. The pump switches and crossfeed valve switches are also used on some aircraft to activate the automatic fuel feed mode. The automatic mode is selected if all switches are set to the ON position. On other aircraft you may find an individual switch to select automatic or manual fuel feed mode. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 11|X−Feed Valve Control/A/B1 Page 152 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 76 HAM US/F SwD 01.12.2007 Individuell Crossfeed Valve 11|X−Feed Valve Control/A/B1 Page 153 FUNDAMENTALS ATA 28 fuel management control panel cont. The controls for the engine fuel shut off valves are always found on the engine fire panel. On most modern aircraft the valves are also controlled by the engine master switches on the engine start panel. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 12|LP Valve Control/A/B1 Page 154 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 77 HAM US/F SwD 01.12.2007 Engine Fuel Shut Off Valve 12|LP Valve Control/A/B1 Page 155 FUNDAMENTALS ATA 28 FUEL FEED SYSTEM INDICATIONS The most important indications for the fuel feed system will be found on the fuel management control panel. This panel shows fuel pump status, valve status and system status. The pump control switches show if the fuel pumps are switched on or off. The crossfeed valve switch shows the position of the crossfeed valve and on the mode selector switch, you can see if the fuel feed system is running in manual or automatic mode. On most modern aircraft the fuel feed system is also shown on the electronic displays such as ECAM. The main information shown on the display is the pump indication and valve indication. The ECAM page also shows additional fuel system information: fuel quantity indication fuel temperature in the tanks fuel used by each engine since engine start total fuel quantity on board FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 13|Feed Syst Indications/A/B1 Page 156 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 78 HAM US/F SwD 01.12.2007 Fuel Feed System Indications 13|Feed Syst Indications/A/B1 Page 157 FUNDAMENTALS ATA 28 FUEL PUMP INDICATION The use of an electronic display unit is the most convenient way to show the condition of the boost pumps. Pressure switches connected to the individual pump outlets are used to indicate the pump status. The pressure switches at the fuel pumps also monitor the performance of the pump. If the delivery pressure of a pump drops below a fixed threshold, a low pressure warning for the pump is initiated. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 14|Fuel Pump Indication/B1 Page 158 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 79 HAM US/F SwD 01.12.2007 Boost Pump Indication 14|Fuel Pump Indication/B1 Page 159 FUNDAMENTALS ATA 28 fuel pump indication cont. On other aircraft the pump low pressure indication may be shown by the amber ’PRESS’ light on the pump switches and by an amber pump symbol on the EICAS display. A low pressure condition is also indicated, if a pump runs out of fuel. In automatic fuel feed mode, normally all the fuel pumps have been switched ON and a computer is controlling the pumps and valves. Pumps which are switched ON but not pumping are said to be armed. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 15|Fuel Pump Indication/B1 Page 160 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 80 HAM US/F SwD 01.12.2007 EICAS Display Low Pressure Indication 15|Fuel Pump Indication/B1 Page 161 FUNDAMENTALS ATA 28 VALVE INDICATION Remember that the engine fuel shut-off valves are activated either by the engine master switch or by the respective fire switch. On the fuel page the valve symbol first changes from in-line to diagonal to indicate that the valve is in transit. When the valve is actually closed, the symbol changes to a cross-line position. Note that the colour of the valve symbol changes to amber, because a closed fuel shut-off valve is not a normal operating condition. Not all aircraft have indications which show the engine shut off valve position. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 16|Valve Indications/B1 Page 162 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 81 HAM US/F SwD 01.12.2007 Valve Status System Pages 16|Valve Indications/B1 Page 163 FUNDAMENTALS ATA 28 valve indication cont. But you will always find crossfeed valves indications. The valve is shown white if it is in the correct condition and in amber if it is not. This example shows a failure condition where the crossfeed valve number 4 has been ordered to open, but remains closed. The reserve tank transfer valves are indicated with arrows on this aircraft. The arrows represent fuel flow from reserve tanks to main tanks but the position of the valves is not shown. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 17|Valve Indications/B1 Page 164 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 82 HAM US/F SwD 01.12.2007 Fuel Feed-Valve Indication 17|Valve Indications/B1 Page 165 FUNDAMENTALS ATA 28 valve indication cont. The status of the reserve tank transfer valves on this aircraft is indicated with a transfer valve symbol on the fuel page. It moves to diagonal to indicate that the valves are in transit and afterwards it moves to the open position. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM HAM US/F SwD 01.12.2007 18|Valve Indications/B1 Page 166 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM Figure 83 HAM US/F SwD 01.12.2007 Transfer Valve Status 18|Valve Indications/B1 Page 167 FUNDAMENTALS ATA 28 FUEL FEED SYSTEM: FUNCTION MECHANICAL FUEL FEED MANAGEMENT On old aircraft fuel feed management was undertaken by the flight engineer who controlled the fuel pumps and valves according to the flight phase. On modern aircraft however, fuel feed management is done automatically using either a pressure controlled or electrically controlled method. There are 2 methods of pressure controlled fuel feed. You may find aircraft which have different kinds of fuel boost pumps installed. Some pumps with standard low output pressure and others with high output pressure. On other aircraft types with the same kind of boost pumps in all the tanks, pressure reducing devices are used to give different output pressure. The high output pressure pumps which are also called override and jettison pumps deliver about twice as much pressure as the standard boost pumps. This high pressure forces discharge check valves on each of the standard pumps to close. This prevents fuel flow from the standard pumps into the fuel feed manifold as long as the override pumps are running. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 01|Introduction/B1 Page 168 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 84 HAM US/F SwD 01.12.2007 Mechanical Fuel Feed Management 01|Introduction/B1 Page 169 FUNDAMENTALS ATA 28 mechanical fuel feed management cont. The other method of achieving different pump pressures is by means of sequence valves. Sequence valves are installed at the pump outlets of some of the standard boost pumps and reduce their output pressure. When the boost pump is running, the sequence valve opens and some fuel returns to the tank. This results in a lower outlet pressure into the feed lines. On systems with sequence valves, we find the same type of boost pumps throughout the fuel system. When the center tank is empty and the center tank pumps no longer deliver enough pressure the wing tank boost pumps open the pump discharge check valves and take over the fuel feed. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 02|Sequence valves/B1 Page 170 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 85 HAM US/F SwD 01.12.2007 Sequence Valves 02|Sequence valves/B1 Page 171 FUNDAMENTALS ATA 28 ELECTRICAL FUEL FEED MANAGEMENT Electrical fuel feed management is performed automatically. It is controlled in accordance with the flight phases. In the taxiing phase, the center tank normally feeds all the engines as you can see on the fuel page. All the other pumps are in standby. The next important flight condition is take−off configuration. The switch over from taxiing fuel feed to take off fuel feed occurs when the flaps are extended before take−off. Now the engines are supplied individually by 2 boost pumps from each of the main tanks 2 and 3 and by the double capacity center tank boost pumps. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 03|Electrical Fuel Feed Management/B1 Page 172 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 86 HAM US/F SwD 01.12.2007 Electrical Fuel Feed Management on Ground 03|Electrical Fuel Feed Management/B1 Page 173 FUNDAMENTALS ATA 28 ELECTRICAL FUEL FEED MANAGEMENT Cruise feed is activated when the aircraft has taken off and the flaps have been retracted again. The center tank and if it is available the stabilizer tank are emptied when the fuel in the center tank and the stabilizer tank has been used, the automatic feed management switches to the inner main tanks. All engines are now supplied by the double capacity override and jettison pumps in the main tanks 2 and 3. Later in the flight, when the reserve tanks have been emptied and the inner main tanks have the same volume of fuel as the outer tanks, then tank to engine fuel feed takes place. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 04|Electrical Fuel Feed Management/B1 Page 174 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 87 HAM US/F SwD 01.12.2007 Electrical Fuel Feed Management in Cruise 04|Electrical Fuel Feed Management/B1 Page 175 FUNDAMENTALS ATA 28 FUEL TRANSFER MANAGEMENT Fuel transfer between tanks in flight is limited, because it changes the aircraft’s center of gravity. It is only permitted from reserve tanks to inner main tanks in equal amounts and on both wings simultaneously. This is to prevent unsafe flight conditions developing. This transfer is controlled automatically if the fuel quantity in the main tanks drops below a predetermined value. The fuel quantity is sensed by level sensors or by the quantity probes in the tanks. For safety reasons there are always 2 transfer valves in each reserve tank, each with an independent power supply. You may also find independent control units. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 05|Fuel Transfer Management/B1 Page 176 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 88 HAM US/F SwD 01.12.2007 Fuel Level Sensing Control Unit 05|Fuel Transfer Management/B1 Page 177 FUNDAMENTALS ATA 28 fuel transfer management cont. Another type of in−flight fuel transfer that can occur, is to and from the trim tank. Aft fuel transfer, from the center tank to the trim tank, is only used to control the center of gravity of the aircraft. Forward fuel transfer from a stabilizer tank to the center tank, makes the fuel available for the engines. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 06|Fuel Transfer Management/B1 Page 178 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 89 HAM US/F SwD 01.12.2007 In Flight Fuel Transfer ”Trim Tank” 06|Fuel Transfer Management/B1 Page 179 FUNDAMENTALS ATA 28 FUEL SCAVENGE The purpose of a fuel scavenge system is to reduce the amount of non−usable fuel in the tanks. The most commonly used method of fuel scavenging uses jet pumps. It is similar to the method already discussed in the water scavenge system. In this example jet pumps ensure that all of the reserve tank fuel can be used and the system is also used to scavenge fuel that has entered the vent tanks. The boost pumps supply the jet pumps with the pressure they need for operation. The scavenged fuel is then pumped into the main inner tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 07|Fuel Scavenge_Jet P./B1 Page 180 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 90 HAM US/F SwD 01.12.2007 Fuel Scavange 07|Fuel Scavenge_Jet P./B1 Page 181 FUNDAMENTALS ATA 28 fuel scavenge cont. Another method of fuel scavenging uses an electrically driven scavenge pump. These pumps are controlled automatically as the fuel level drops below a certain threshold. As with the jet pumps they pump fuel into a main fuel tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 08|Fuel Scavenge_Elec P./B1 Page 182 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 91 HAM US/F SwD 01.12.2007 Electrically Scavenge Pump 08|Fuel Scavenge_Elec P./B1 Page 183 FUNDAMENTALS ATA 28 FUEL RECIRCULATION On some aircraft a fuel recirculation system ensures proper cooling of the engine oil and the integrated drive generator oil. Fuel from a tank is pumped through the engine oil cooler which heats the fuel and cools the engine oil. The fuel then passes through the high pressure gear driven engine pump to the burners on the engine. Some of the fuel is diverted and passes through a bypass valve to the IDG cooler. The fuel is heated further and then recirculated and mixed with new fuel ready to repeat the process. All works well until the engine runs at low speed and there is a high electrical load on the IDG. As the engine runs slower the cooling becomes critical because there may not be enough fuel for cooling. Less fuel for cooling results in higher engine oil temperature, which activates the solenoid on the fuel return valve. The fuel return valve opens and lets the hot fuel return to the fuel tank. The fuel returning to the fuel tank could be very hot, and it would be too dangerous to feed it into the fuel tank. So some of the cold fuel entering the system is mixed with the hot fuel before its return to the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 09|Fuel Recirculation System/B1 Page 184 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 92 HAM US/F SwD 01.12.2007 Fuel Recirculation 09|Fuel Recirculation System/B1 Page 185 FUNDAMENTALS ATA 28 FUEL BOOST PUMP FUNCTION The fuel boost pumps are either installed outside the tank on the front or rear spars, or they are found in an explosion proof canister inside the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 10|Fuel Boost Pump Location/B1 Page 186 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 93 HAM US/F SwD 01.12.2007 Fuel Boost Pumps 10|Fuel Boost Pump Location/B1 Page 187 FUNDAMENTALS ATA 28 fuel boost pump function cont. Here you can see a fuel boost pump installed inside a tank. The pumps are generally impeller type pumps, and consist of an AC motor which drives an impeller wheel. The spinning impeller forces the fuel from the inlet to the pump outlet by centrifugal force. It is possible to remove the fuel boost pumps from their canisters without emptying the fuel tank. This is done using a special removal valve which shuts off the fuel inlet as the pump is pulled out of the canister. The removal valve first closes the pump inlet when the pump element is pulled. However on other aircraft types you may find removal valves that do not work automatically and must be closed by a handle. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION HAM US/F SwD 01.12.2007 11|Fuel Boost Pump Installation/B1 Page 188 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL FEED SYSTEM: FUNCTION Figure 94 HAM US/F SwD 01.12.2007 Discription of the Fuel Boost Pump 11|Fuel Boost Pump Installation/B1 Page 189 FUNDAMENTALS ATA 28 DEFUELING AND FUEL TRANSFER PRESSURE DEFUELING There are 2 methods of defueling an aircraft. These are pressure defueling and suction defueling. Pressure defueling is when you defuel the aircraft using the tank boost pumps. The 25 to 50 psi output pressure of the boost pumps allows for fast defueling. The pumps feed fuel through the fuel feed manifold to the next component that is needed for defueling. This component, used for defueling, is the defuel transfer valve. It is a motor driven valve and interconnects the fuel feed manifold and the refueling manifold. On BOEING aircraft, these valves are called manual defueling valves because they are manually operated. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER HAM US/F SwD 01.12.2007 01|Pressure Defueling/A/B1 Page 190 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER Figure 95 HAM US/F SwD 01.12.2007 Defueling A320 01|Pressure Defueling/A/B1 Page 191 FUNDAMENTALS ATA 28 Pressure defueling cont. When you open the defuel transfer valve it allows fuel flow into the refueling manifold. A check valve prevents any reverse flow from the refueling manifold into the feed manifold. You can see that for pressure defueling the fuel feed manifold is interconnected to the refueling manifold. Pressure defueling is the preferred method for defueling an aircraft. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER HAM US/F SwD 01.12.2007 02|Defuel Transfer Valve/A/B1 Page 192 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER Figure 96 HAM US/F SwD 01.12.2007 Defuel Transfer Valve 02|Defuel Transfer Valve/A/B1 Page 193 FUNDAMENTALS ATA 28 SUCTION DEFUELING Suction defueling is when you use suction from the fuel tank truck to defuel the aircraft. The minimum suction required for defueling is about 10 to 15 psi. Suction defueling uses nearly all the same components as pressure defueling. Some tanks have boost pump bypass valves that allow the fuel to enter the fuel feed manifold. The manual defueling valve must also be open during suction defueling to allow the fuel truck to suck out the fuel. If the cross−feed valve is open, fuel is drawn out of both wing tanks. One major disadvantage of suction defueling is that it is difficult to defuel 1 tank without defueling other tanks. It also takes longer than pressure defueling and not all tanks can be defueled by this method. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER HAM US/F SwD 01.12.2007 03|Suction Defueling/A/B1 Page 194 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER Crossfeed Valve Figure 97 HAM US/F SwD 01.12.2007 Suction Defueling 03|Suction Defueling/A/B1 Page 195 FUNDAMENTALS ATA 28 FUEL TRANSFER As you already know, fuel transfer is simply a combination of defueling from 1 tank and putting the fuel into another tank. When you perform a fuel transfer you use the fuel boost pumps the fuel feed manifold the defueling or defuel transfer valve the refueling manifold and the refueling valves that allow fuel into another tank. Fuel transfer is ALWAYS done manually and NEVER by the automatic refueling system. To transfer fuel from one tank to another, you: turn on the boost pumps in the tanks you want to empty, open the cross−feed valve if required, open the refueling valve of the tank to be filled, and start to transfer fuel by opening the defuel transfer valve. Remember, you must transfer fuel if you need to balance the aircraft after incorrect refueling or if you need to empty a fuel tank for maintenance purposes. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER HAM US/F SwD 01.12.2007 04|Fuel Transfer/A/B1 Page 196 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS DEFUELING AND FUEL TRANSFER Figure 98 HAM US/F SwD 01.12.2007 Manually Fuel Transfer 04|Fuel Transfer/A/B1 Page 197 FUNDAMENTALS ATA 28 TRIM TANK SYSTEM BASIC PRINCIPLE Trim tank systems are used to increase the efficiency of an aircraft in flight and therefore to reduce fuel consumption. Fuel saving is achieved because the trim tank system reduces the aerodynamic drag in flight. To fully understand the basic principle of a trim tank system it would be helpful for you to look at the aerodynamics unit before you continue this segment. The trim tank system controls the aircraft’s center of gravity by forward or aft fuel transfer. So, in order to understand the trim tank you have to examine the aircraft’s center of gravity in some detail. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 01|Basic Principle/A/B1 Page 198 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 99 HAM US/F SwD 01.12.2007 Trim Tank Basic Prinziples 01|Basic Principle/A/B1 Page 199 FUNDAMENTALS ATA 28 basic principle cont. From the aerodynamic lesson you know that 4 major forces act on an aircraft in flight such as: the lift the weight the thrust and the drag. The forces shown would result in a downward pitch of the aircraft. To counteract this downward pitch, the horizontal stabilizer is deflected, so that it creates an opposing downward force which brings the aircraft back to a horizontal attitude. This additional downward force at the stabilizer must be compensated for by a higher lift which results in higher aircraft drag. An aircraft with a trim tank system creates the required downward force by transferring fuel load from the forward tanks to the stabilizer tank. No additional lift is required, because the total aircraft weight remains the same. However, transferring fuel to the tail moves the aircraft‘s center of gravity aft which results in less aircraft stability. Therefore, on an aircraft with a trim tank the center of gravity must be controlled. In order to control the center of gravity the system must determine where the actual center of gravity is. This is only possible, if the system already knows where the center of gravity was before the engines were started. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 02|Basic Principle/A/B1 Page 200 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 100 HAM US/F SwD 01.12.2007 Aircraft Trim Tank 02|Basic Principle/A/B1 Page 201 FUNDAMENTALS ATA 28 CENTER OF GRAVIVTY DETERMINATION An aircraft’s actual center of gravity is determined by the manufacturer upon delivery. The center of gravity of the empty aircraft is used as the base for the loading sheets. Loading affects the center of gravity. Refueling also changes the aircraft’s center of gravity. During refueling the center of gravity moves first a little bit aft, because the outer wing tanks are filled first and then it moves forward when the inner and center tanks are filled. The filling of the trim tank finally moves the center of gravity aft again. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 03|CG Determination/B1 Page 202 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 101 HAM US/F SwD 01.12.2007 Center of Gravity 03|CG Determination/B1 Page 203 FUNDAMENTALS ATA 28 center of gravivty determination cont. The center of gravity resulting from cargo loading and passenger loading is called zero fuel weight center of gravity which is calculated by the flight crew prior to flight. The zero fuel weight and the calculated zero fuel weight center of gravity are entered into the flight management computer via the MCDU and transmitted to the fuel control computer to serve as a base reference for the gross weight center of gravity calculation. The fuel control computer also uses data from the fuel quantity measuring system for this calculation. Based on the zero fuel weight center of gravity before engine start, the fuel control computer calculates the actual center of gravity in flight. Because the fuel weight is the only parameter which changes the center of gravity during flight, the fuel control computer uses the tank quantity information to determine the center of gravity. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 04|CG Determination/B1 Page 204 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 102 HAM US/F SwD 01.12.2007 Center of Gravity 04|CG Determination/B1 Page 205 FUNDAMENTALS ATA 28 center of gravivty determination cont. For safety reasons, the center of gravity is also calculated by the flight management computer. It is calculated based upon flight data like airspeed, thrust, stabilizer position and the previously stored zero fuel weight center of gravity. This value is transmitted to the fuel control computer which now compares both calculated centers of gravity and if they are within acceptable limits, it allows the trim tank system to work. Remember that an aft center of gravity reduces the stability of the aircraft. To prevent dangerous flight conditions, the fuel control computer ensures that the actual center of gravity will never move beyond the critical point. The computer tries to achieve an acceptable center of gravity, this is called the target center of gravity. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 05|CG Determination/B1 Page 206 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 103 HAM US/F SwD 01.12.2007 Change of Gravity Center 05|CG Determination/B1 Page 207 FUNDAMENTALS ATA 28 center of gravivty determination cont. The fuel control computer must also ensure, that center of gravity control is not operational at take−off or landing. Therefore, center of gravity control is only available above a pre−determined flight altitude or until a defined number of minutes before touch down. Remember that the center of gravity location is always referred to as a percentage of mean aerodynamic chord. For additional safety you will find that the target center of gravity is approximately 2% forward of the certified aft limit of the aircraft. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 06|CG Determination/B1 Page 208 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 104 HAM US/F SwD 01.12.2007 Center of Gravity Limit 06|CG Determination/B1 Page 209 FUNDAMENTALS ATA 28 TRIM TANK SYSTEM FUNCTION When aircraft has reached the cruising altitude the center of gravity control system is activated. The center of gravity control works as follows: First fuel is taken from the forward fuel tanks until the center of gravity reaches the target center of gravity. Then fuel is transferred forward until the center of gravity moves 0.5% forward of the target center of gravity. And thereafter, fuel is taken from the forward fuel tanks again until the target center of gravity is reached again. The center of gravity control band is the area in which the center of gravity is allowed to move forwards and backwards. The center of gravity control will continue until the aircraft descents below a specified flight level or until approximately 75 minutes remain to calculated touch down. At this point all remaining fuel in the trim tank will be transferred forward to have a safe center of gravity for landing. Even if the aircraft took off with an empty trim tank, the center of gravity control system will work when the required flight altitude is reached. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 07|TT System Function/A/B1 Page 210 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 105 HAM US/F SwD 01.12.2007 Trim Tank System Function 07|TT System Function/A/B1 Page 211 Lufthansa Technical Training FOR TRAINING PURPOSES ONLY! FUEL SYSTEMS TRIM TANK SYSTEM FUNDAMENTALS ATA 28 SYSTEM ORGANIZATION The main components in center of gravity control system are: The fuel control computer, which determines the aircraft’s center of gravity and monitors and controls the components of the system, Several transfer valves and tank inlet valves which provide aft and forward fuel transfer. Isolation valves which shut off the trim tank and the trim tank transfer pipe, Fuel level sensors in each tank which back up the fuel quantity signals for safety reasons, and The fuel boost pumps and transfer pumps which enable aft fuel transfer. The wing tank fuel boost pumps enable aft fuel transfer via the open crossfeed valves to the aft transfer valves if the center tank is empty. The trim pipe isolation valve is only opened after the required flight altitude is reached to allow center of gravity control. This valve is mainly used to enable aft fuel transfer from the center tank transfer pumps. It is used for forward fuel transfer if the center tank is empty. The auxiliary forward transfer valve is used for forward fuel transfer into the center tank if the center tank is not empty. The aft transfer valves are used for aft fuel transfer from the wing tank boost pumps via the trim pipe isolation valve and the trim tank inlet valve. The transfer pumps are used for aft transfer from the center tank and, on this aircraft, they are also used to transfer fuel from the center tank to the wing tank collector boxes which, in turn, supply the engines. The trim tank isolation valve is used to enable or to shut-off forward fuel transfer via the auxiliary forward transfer valve or via the trim pipe isolation valve depending whether the center tank holds fuel or not. This valve is always closed until the required flight altitude is reached for center of gravity control. HAM US/F SwD 01.12.2007 08|TT Components/B1 Page 212 FUNDAMENTALS ATA 28 Crossfeed Valve 1 Crossfeed Valve 2 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 106 HAM US/F SwD 01.12.2007 Crossfeed Valve 3 Components of Gravity Control System 08|TT Components/B1 Page 213 FUNDAMENTALS ATA 28 System Organization cont. The trim tank inlet valve allows fuel at aft fuel transfer to enter the trim tank. This valve is also opened for trim tank refueling. The high level sensors in the center tank and inner wing tanks are used to prevent forward fuel transfer if the respective tank is full so that the tank will not overflow. You will remember that these sensors also terminate refueling if the tank is full. The low level sensor in the trim tank terminates the forward fuel transfer if the trim tank is empty. The low level sensor in the center tank signals to the fuel control computer to change to forward fuel transfer into the wing tanks if the center tank is empty. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 08a|TT Components/B1 Page 214 FUNDAMENTALS ATA 28 Crossfeed Valve 1 Crossfeed Valve 2 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Figure 107 HAM US/F SwD 01.12.2007 Crossfeed Valve 3 Components of Gravity Control System 08a|TT Components/B1 Page 215 Lufthansa Technical Training FOR TRAINING PURPOSES ONLY! FUEL SYSTEMS TRIM TANK SYSTEM FUNDAMENTALS ATA 28 TRIM TANK CONTROLS You find the controls for the trim tank on the fuel control panel in the cockpit. In this example you can see: a trim tank mode pushbutton and a trim tank selector switch. The trim tank mode switch is used to operate the center of gravity control system in automatic mode or in manual forward transfer mode. This switch is normally in the AUTO position so that the center of gravity control system can perform forward and aft fuel transfer as required. If a failure occurs in the automatic center of gravity control, this switch allows selection of manual forward mode. If forward manual transfer mode is selected, the automatic trim transfers for center of gravity control are overridden and the trim tank is emptied into the center tank via the open trim tank isolation valve, trim tank inlet valve and the auxiliary forward transfer valve. This forward transfer is switched off, when the low level sensor in the trim tank signals an empty trim tank. The trim tank feed selector switch is normally guarded in the AUTO position. This position arms all valves for the automatic center of gravity control. The isolation position of the trim tank feed selector enables total isolation of the trim tank from the other tanks. When the ISOL position is selected all valves are closed which interconnect the trim tank with the forward tanks. When the trim tank feed selector is in the OPEN position with forward mode selected, the low level sensor in the trim tank is overriden so that the trim tank feed line can be drained for maintenance purposes. HAM US/F SwD 01.12.2007 09|TT Controls/B1 Page 216 FUNDAMENTALS ATA 28 Crossfeed Valve 1 Crossfeed Valve 2 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Crossfeed Valve 3 Figure 108 HAM US/F SwD 01.12.2007 Trim Tank Manuel Control 09|TT Controls/B1 Page 217 FUNDAMENTALS ATA 28 TRIM TANK INDICATIONS The trim tank mode selector has an illuminated forward light, this indicates to you that the trim system is working in manual forward transfer mode. An illuminated fault light alerts you to a dangerous center of gravity condition or to system failures in the trim tank system. The system is permanently monitored by the fuel control computer. ECAM indications: A green forward pointing arrow indicates normal forward transfer. The arrow changes to a solid one if manual forward transfer is selected and it points aft if the system performs a normal aft fuel transfer. It changes to amber and points in the respective direction if fuel transfer is abnormal. The valve symbol below the arrow represents the trim tank isolation valve and the trim tank inlet valve. The symbol is shown in green when both valves are normally open or closed. The valve symbol is also shown in amber if one or both valves are open when they have been ordered closed. Additional trim tank indications you may find are the gross weight of the aircraft which is displayed at the bottom right of the ECAM screen and the center of gravity indication displayed as a percentage of MAC which is shown below. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM HAM US/F SwD 01.12.2007 10|TT Indications/B1 Page 218 FUNDAMENTALS ATA 28 Crossfeed Valve 1 Crossfeed Valve 2 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS TRIM TANK SYSTEM Crossfeed Valve 3 Figure 109 HAM US/F SwD 01.12.2007 Trim Tank Indications 10|TT Indications/B1 Page 219 FUNDAMENTALS ATA 28 JETTISON SYSTEM INTRODUCTION A jettison system allows the pilot to dump fuel overboard to prevent exceeding the maximum landing weight of the aircraft. All aircraft have a higher take off weight than landing weight and most of them are designed to perform overweight landings. Some aircraft, however, for extra safety, have jettison systems to prevent high stress on the fuselage during overweight landings. The jettison system also ensures that the aircraft is light enough for a go−around in case of an engine failure. The jettison system design makes it impossible to empty ALL tanks during flight. Complete emptying of the tanks is prevented by some of the fuel tanks not being connected to the jettison system or by other design features. This ensures that a minimum of fuel is kept so that the aircraft can reach the next airport. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 01|Introduction/A/B1 Page 220 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 110 HAM US/F SwD 01.12.2007 Fuel Jettison System 01|Introduction/A/B1 Page 221 FUNDAMENTALS ATA 28 ORGANIZATION This graphic shows a typical jettison system with its major components. One of the major components is the jettison line, that ports the fuel to the outlets where it is dumped overboard. Some aircraft have special jettison pumps and other aircraft use the standard fuel boost pumps for jettisoning fuel. Although the pumps look the same, the special jettison pumps have a greater flow and pressure capacity. This extra capacity allows these pumps to dump large amounts of fuel quickly. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 02|Organisation/B1 Page 222 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 111 HAM US/F SwD 01.12.2007 Organization 02|Organisation/B1 Page 223 FUNDAMENTALS ATA 28 Organization cont. The jettison transfer valves must be open, to get the fuel from the jettison pumps into the jettison line. To save weight the jettison lines are very often shared with the refueling manifold. Because this refueling manifold is then pressurized during jettison operation you may find valves on some aircraft, that protect the refueling couplings against leaks. The manual fueling shut off valves are additional valves between the refueling coupling and the refueling manifold to protect the couplings against leaks. The jettison nozzle valves at the end of the jettison line open to dump the fuel overboard via the jettison nozzles. The jettison nozzles ensure that the fuel remains in a non−vaporized compact flow so that it drops quickly away from the aircraft. These special jettison nozzles are also called anti−corona outlets. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 03|Organisation/B1 Page 224 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 112 HAM US/F SwD 01.12.2007 Organization 03|Organisation/B1 Page 225 FUNDAMENTALS ATA 28 CONTROL PANEL The jettison control panel is normally located on the overhead panel for easy access to both pilots. To prevent accidental fuel jettison, the panel has controls to arm the system to prepare for jettison and controls to start jettison of the fuel. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 04|Control Panel/A/B1 Page 226 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 113 HAM US/F SwD 01.12.2007 Control Panel 04|Control Panel/A/B1 Page 227 FUNDAMENTALS ATA 28 CONTROLS AND INDICATION In this example the fuel jettison control selector switch is a 3 position switch. When you set the selector switch to A or B position, you select a channel or card in the fuel jettison computer, to control and monitor fuel jettison. Selecting a card is 1 of 2 preconditions to activate the jettison system. Two cards or channels in the computer are provided for safety reasons. The second precondition is activated by the jettison nozzle valve switches. These switches open or close the respective jettison fuel nozzle valves. The switches are guarded so that it is impossible to move them by accident. The nozzle valve switch in the ON position sends a signal to the jettison control computer. The third precondition is the selection of the fuel to remain on board after jettison. It is selected with a knob and displayed on the fuel synoptic. The computer checks the selected fuel to remain and compares this selection with the amount of fuel on board. If total fuel is more than fuel to remain selection, the computer sends signals to activate all override/jettison pumps and opens all cross−feed valves. You can monitor the jettison operation on the EICAS fuel page. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 05|Controls and Indication/B1 Page 228 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 114 HAM US/F SwD 01.12.2007 Controls and Indication 05|Controls and Indication/B1 Page 229 FUNDAMENTALS ATA 28 controls and indication cont. You can see that the jettison operation is clearly shown in magenta on this aircraft type. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 06|Controls and Indication/B1 Page 230 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 115 HAM US/F SwD 01.12.2007 Jettison Indication 06|Controls and Indication/B1 Page 231 FUNDAMENTALS ATA 28 Controls and indication cont. This example shows the jettison control panel of a different aircraft with only 2 switches, 1 to arm the jettison system and 1 to activate it. The fuel to remain is selected indirectly as the jet gross weight which is the total landing weight of the aircraft. This setting is made on the MCDU before flight and displayed in the JET GW field. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 07|Controls and Indication/B1 Page 232 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 116 HAM US/F SwD 01.12.2007 Jettison Controls on Airbus A340 07|Controls and Indication/B1 Page 233 FUNDAMENTALS ATA 28 OPERATION During the jettison operation, the jettison valves are either closed automatically or by the flight crew when the desired fuel level is reached. This example is set for a jet gross weight of 186 000 kg representing a fuel to remain weight of 40 000 kg. You can see that the jettison stops automatically when the preselected landing weight of 186 000 kg is reached with 40 000 kg of fuel remaining in the tanks. In the next example the jet gross weight is set to 169 000 kilograms which is identical to the zero fuel weight. During this jettison operation, fuel level sensors in the tanks signal when the minimum allowed fuel quantity is reached and stop the operation. Here the remaining fuel quantity is 6 400 kg. However, jettison can be interrupted at any time by operating the jettison control switches. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 08|Jettison Operation/B1 Page 234 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 117 HAM US/F SwD 01.12.2007 Operation 08|Jettison Operation/B1 Page 235 FUNDAMENTALS ATA 28 operation cont. Another method to terminate fuel jettison is achieved by the arrangement of the fuel pump inlets. The jettison pump inlets are located above the floor of the tanks. This arrangement means the pumps run dry when the minimum fuel level is reached. Note, that in this example the fuel to remain is set to zero. You see, that fuel jettisoning stops when the jettison pumps run dry. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM HAM US/F SwD 01.12.2007 09|Jettison Operation/B1 Page 236 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS JETTISON SYSTEM Figure 118 HAM US/F SwD 01.12.2007 Jettison Termination by Pump Inlets 09|Jettison Operation/B1 Page 237 FUNDAMENTALS ATA 28 ELECTRICAL FUEL INDICATION AND SENSING INTRODUCTION All information that is necessary to monitor the fuel system is presented on the ECAM or EICAS displays in the cockpit. The total amount of fuel is presented on both the ECAM and the EICAS displays. Fuel on board, or FOB, is expressed in kilograms on the ECAM display and total fuel is expressed in metric tons on the EICAS display. Fuel temperature is also indicated on the EICAS display. This fuel data is always displayed. For all other fuel related information you must select the fuel system pages of the lower displays. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 01|Introduction/A/B1 Page 238 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 119 HAM US/F SwD 01.12.2007 ECAM or EICAS Fuel Display 01|Introduction/A/B1 Page 239 FUNDAMENTALS ATA 28 introduction cont. The fuel system pages provide all other information necessary to monitor the fuel system. In addition to valve and pump status information, data on the quantity of fuel in each individual tank and on the total fuel on board is displayed. Fuel temperature is shown on the ECAM display. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 02|Introduction/A/B1 Page 240 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 120 HAM US/F SwD 01.12.2007 Fuel System Pages 02|Introduction/A/B1 Page 241 FUNDAMENTALS ATA 28 FUEL QUANTITY INDICATION All the fuel system information on the cockpit displays is derived from signals provided by sensors located inside the fuel tanks. A computer, normally called the fuel quantity computer, uses these tank sensor signals to calculate all the output data for indications on the cockpit displays and the control panels and also for automatic system control. The fuel quantity is indicated as a mass, in kilograms or tons. It is very important to have information on the actual fuel weight as accurate as possible not only for indication, but also to allow the flight management system to calculate all the data that is necessary to operate the aircraft in a safe and economic way. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 03|Fuel Qty Ind/A/B1 Page 242 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 121 HAM US/F SwD 01.12.2007 Fuel Quantity Indication System 03|Fuel Qty Ind/A/B1 Page 243 FUNDAMENTALS ATA 28 FUEL QUANTITY PROBES Let’s now have a closer look at the fuel quantity probes, also called tank units. The number of probes in a tank depends on the size and shape of the tank. The probes are installed vertically in each tank and reach from the bottom of the tank to the top. The probes are therefore of different length. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 04|Fuel Qty Probes/B1 Page 244 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 122 HAM US/F SwD 01.12.2007 Fuel Quantity Probes 04|Fuel Qty Probes/B1 Page 245 FUNDAMENTALS ATA 28 Fuel quantity probes cont. Each fuel quantity probe consists of 2 thin walled aluminium alloy tubes. The tubes are installed coaxially and electrically isolated from each other to form a capacitor. Each probe also consists of a terminal block which contains the electrical connection and the mounting brackets which fix the probe to the tank structure. The space between the 2 tubes of the fuel quantity probe is filled with air when the tank is empty or partially or completely filled with fuel depending on the level of fuel in the tank. The capacitance, C in short, of a fuel quantity probe is its capability to store electrical energy, and depends on the area of the plates, called A, and on the distance between the plates, d. It also depends on the material that replaces the air between the tubes. For example when the probe is completely covered by fuel, the capacitance is increased by a factor of 2.2. This material dependent factor is called the dielectric constant. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 05|Fuel Qty Probes/B1 Page 246 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 123 HAM US/F SwD 01.12.2007 Fuel Quantity Probe Architecture 05|Fuel Qty Probes/B1 Page 247 FUNDAMENTALS ATA 28 Fuel quantity probes cont. The fuel quantity computer measures the capacitance of all probes and calculates the fuel level from this. When the computer knows the fuel level, it can calculate the fuel quantity, because the shape of the tank is stored in its memory. The computer can calculate the correct fuel level even if 1 of the probes is faulty. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 06|Fuel Qty Probes/B1 Page 248 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 124 HAM US/F SwD 01.12.2007 Fuel Quantity Probes 06|Fuel Qty Probes/B1 Page 249 FUNDAMENTALS ATA 28 FUEL CHARACTERISTICS SENSORS To enable it to calculate the fuel mass from the fuel level with a high degree of accuracy, the computer needs additional information. This additional information is provided by the fuel characteristics sensors. These sensors measure the density and the dielectric constant of the fuel. The fuel characteristics sensors are located at the lowest part of the tanks so that they remain covered by fuel for as long as possible. Two fuel characteristics sensors are located in each tank, a compensator and a densitometer. The densitometer measures the fuel density which is the main correction factor between the measured fuel level and the fuel mass. The densitometer uses either a vibration sensor with frequency depending on the fuel density or an automatic hydrometer. The compensator is constructed like a fuel quantity sensor. However its capacitance is only dependent on the fuel dielectric constant and not on the fuel level because it is always fully covered by fuel. The compensators signal corrects the variation of the dielectric constant due to temperature and different fuel brands. On Airbus aircraft the compensator and the densitometer are combined in 1 unit called the cadensicon. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 07|Fuel Charactr Sensors/B1 Page 250 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 125 HAM US/F SwD 01.12.2007 Fuel Characteristics Sensors 07|Fuel Charactr Sensors/B1 Page 251 FUNDAMENTALS ATA 28 Fuel Characteristics Sensors cont. The accuracy of fuel quantity calculation is normally greater than 99%. To improve accuracy further the different wing bending between ground and air and the effect of aircraft attitude changes can be taken in account. A degraded accuracy of calculation is shown on the ECAM display, for example, by amber lines on top of the last two digits of the indication. This can occur if, for example, the computer replaces a correction signal, such as fuel density or the dielectric constant, with a standard value. This could happen in the event of a sensor failure. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 08|Fuel Charactr Sensors/B1 Page 252 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 126 HAM US/F SwD 01.12.2007 Fuel Quantity Calculation 08|Fuel Charactr Sensors/B1 Page 253 FUNDAMENTALS ATA 28 FUEL LEVEL SENSORS The fuel level sensing system is independent of the fuel quantity system and is used mainly for automatic fuel system control. The fuel level sensing system uses level sensors that are installed in different locations in the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 09|Fuel Level Sensing System/A/B1 Page 254 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 127 HAM US/F SwD 01.12.2007 Fuel Level Sensing System 09|Fuel Level Sensing System/A/B1 Page 255 FUNDAMENTALS ATA 28 FUEL LEVEL SENSORS The fuel level sensing system is independent of the fuel quantity system and is used mainly for automatic fuel system control. The fuel level sensing system uses level sensors that are installed in different locations in the tank. The fuel level sensors have different names depending on their location in the tank or on their function. Examples of names that depend on location would be high level sensor and low level sensor. Other sensors installed in an intermediate position do not have a location dependent name. When the fuel level reaches a sensor, the sensor triggers a certain automatic control function via the computer. Different types of sensors are used for fuel level sensing. All types send a signal, indicating a state change, to the computer when the fuel level reaches the sensor. Three widely used examples of fuel level sensor are the float switch the thermistor type sensor and the single point sensor. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 10|Fuel Level Sensors/B1 Page 256 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 128 HAM US/F SwD 01.12.2007 Fuel Level Sensing System 10|Fuel Level Sensors/B1 Page 257 FUNDAMENTALS ATA 28 Fuel Level Sensors cont. The float switch contains a reed type switch which has an open contact when the fuel level is low. When the fuel level rises, a permanent magnet floats up and closes the switch contact. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 11|Fuel Level Sensors/B1 Page 258 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 129 HAM US/F SwD 01.12.2007 Float Switch 11|Fuel Level Sensors/B1 Page 259 FUNDAMENTALS ATA 28 Fuel Level Sensors cont. The thermistor type sensor uses the different thermal conductivity of air and fuel to detect the fuel level. When the fuel level is low, the resistance of the thermistor is high. This is because the thermistor is heated by the air current to a high temperature. When the fuel level rises the resistance of the thermistor falls. This is because the temperature of the thermistor decreases due to the higher thermal conductivity of fuel. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 12|Fuel Level Sensors/B1 Page 260 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 130 HAM US/F SwD 01.12.2007 Thermistor Type Sensor 12|Fuel Level Sensors/B1 Page 261 FUNDAMENTALS ATA 28 Fuel Level Sensors cont. The third example of a fuel level sensor is the single point sensor. The single point sensor is constructed like a fuel quantity tank probe and is so called because it is very short. The single point sensor uses the effect of fuel on a capacitor in the same way as the fuel quantity probes. With the single point sensor, when the fuel level is low the capacitance of the sensor is low and when the fuel level rises the capacitance increases because of the higher dielectric constant of fuel. This is detected by the computer which activates the corresponding switching function. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 13|Fuel Level Sensors/B1 Page 262 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 131 HAM US/F SwD 01.12.2007 Single Point Sensor 13|Fuel Level Sensors/B1 Page 263 FUNDAMENTALS ATA 28 FUEL TEMPERATURE INDICATION Finally in this lesson we take a look at the fuel temperature indication. Fuel temperature in one tank is indicated on the EICAS upper display and individual temperature values for each wing tank are displayed on the ECAM fuel system page. A thermistor is used to measure the fuel temperature. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 14|Fuel Temp Indic/A/B1 Page 264 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 132 HAM US/F SwD 01.12.2007 Fuel Temperature Indication 14|Fuel Temp Indic/A/B1 Page 265 FUNDAMENTALS ATA 28 Fuel Temperature Indication cont. Two types of thermistor are used for fuel temperature sensing in different aircraft types. Boeing aircraft use a temperature bulb with PTC characteristics as a thermistor. The temperature bulb is installed in one of the wing tanks at the rear spar. The bulb can be replaced without draining the tank as it is installed in an adapter assembly which stays in the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 15|Fuel Temp Indic/A/B1 Page 266 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 133 HAM US/F SwD 01.12.2007 Fuel Temperature Sensor Installation 15|Fuel Temp Indic/A/B1 Page 267 FUNDAMENTALS ATA 28 Fuel Temperature Indication cont. Two types of thermistor are used for fuel temperature sensing in different aircraft types. Boeing aircraft use a temperature bulb with PTC characteristics as a thermistor. The temperature bulb is installed in 1 of the wing tanks at the rear spar. The bulb can be replaced without draining the tank as it is installed in an adapter assembly which stays in the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING HAM US/F SwD 01.12.2007 16|Fuel Temp Indic. Boeing/B1 Page 268 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS ELECTRICAL FUEL INDICATION AND SENSING Figure 134 HAM US/F SwD 01.12.2007 Fuel Temperature Sensor Installation 16|Fuel Temp Indic. Boeing/B1 Page 269 FUNDAMENTALS ATA 28 MECHANICAL QUANTITY INDICATION SYSTEM MEASURING STICK ARRANGEMENT The mechanical indication system has of a set of measuring sticks which are installed in the fuel tanks. You can use the measuring sticks as back up for the electrical indication system. The sticks measure the fuel level in a tank. Two or more measuring sticks are required to determine the fuel quantity in irregular shaped tanks like wing tanks. On regular shaped tanks like the center tank, you will normally find just 1 measuring stick. The measuring sticks are designed to fit a certain position in a tank. They are not interchangeable with sticks in other locations. The number of measuring sticks in a tank depends on the shape of the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 01|Stick Arrangement/A/B1 Page 270 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 135 HAM US/F SwD 01.12.2007 Measuring Stick Arrangement 01|Stick Arrangement/A/B1 Page 271 FUNDAMENTALS ATA 28 MEASURING STICK FUNCTION Two different types of measuring devices are used to manually check the fuel level in a tank. These devices are drip sticks and manual magnetic level indicators. Drip sticks are only found on older aircraft types. The drip sticks have a calibrated rod which reaches into the fuel tank. The drip sticks are locked to the lower wing surface by locking pins. When the open port of the tube reaches the fuel level, fuel enters the tube and comes out at the drip hole. Then you can take the reading for the fuel level. The reading is always taken at the base of the measuring stick. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 02|Stick Function/A/B1 Page 272 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 136 HAM US/F SwD 01.12.2007 Measuring Stick Function 02|Stick Function/A/B1 Page 273 FUNDAMENTALS ATA 28 Measuring Stick Function cont. The more modern method of determining the fuel level is by using manual magnetic level indicators. These sticks allow measurement of the fuel level without the disadvantage of fuel dripping out of drip holes. The manual magnetic level indicators have a calibrated stick in a sealed tube housing. A float surrounding the tube housing is used to determine the fuel level in the tank. The float rises and falls with the fuel surface. A magnet inside the float provides a connection to another magnet at the top of the measuring stick. Once the magnets engage you can note the reading. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 03|Stick Function/A/B1 Page 274 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 137 HAM US/F SwD 01.12.2007 Manuel Magnetic Level Indicator 03|Stick Function/A/B1 Page 275 FUNDAMENTALS ATA 28 MEASURING STICK READING The stick reading plane of a magnetic level indicator is normally the lower wing surface as shown here. The measuring stick may be calibrated in kilograms, pounds, centimeters or units depending on what the customer wants. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 04|Stick Reading/B1 Page 276 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 138 HAM US/F SwD 01.12.2007 Manuel Magnetic Level Indicator 04|Stick Reading/B1 Page 277 FUNDAMENTALS ATA 28 Measuring Stick Function cont. You know that the stick measures the fuel level and that the fuel level reading corresponds to a volume in the tank. Note that if the float is at the very top of the tank it does not mean that the fuel level is there as well. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 05|Stick Reading/B1 Page 278 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 139 HAM US/F SwD 01.12.2007 Meassuring Stick Readings 05|Stick Reading/B1 Page 279 FUNDAMENTALS ATA 28 Measuring Stick Function cont. In order to get an accurate reading you must lower the sticks in succession from outboard to inboard until you get the first positive reading. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 06|Stick Reading/B1 Page 280 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 140 HAM US/F SwD 01.12.2007 Stick Reading 06|Stick Reading/B1 Page 281 FUNDAMENTALS ATA 28 Measuring Stick Function cont. As fuel level inside the tank changes with aircraft attitude the aircraft pitch and roll attitude must be determined before you take any stick reading. Be aware that the aircraft attitude must be within the type specific limits when using the manual level indicators. Aircraft attitude may change if the aircraft is parked on uneven ground. You should also be aware that some aircraft have a pitch down attitude even when parked on level ground. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 07|Stick Reading/B1 Page 282 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 141 HAM US/F SwD 01.12.2007 Aircraft Attitude on Ground 07|Stick Reading/B1 Page 283 FUNDAMENTALS ATA 28 AIRCRAFT ATTITUDE DETERMINATION The 3 main methods used to determine the aircraft attitude on ground are the inclinometer method, the plumb method, and the attitude monitor method. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 08|Attitude Determ/B1 Page 284 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 142 HAM US/F SwD 01.12.2007 Attitude Determination Methods 08|Attitude Determ/B1 Page 285 FUNDAMENTALS ATA 28 Aircraft Attitude Determination cont. Inclinometer Method The inclinometers use 1 of 2 basic principles. Some work like standard bubble type spirit−levels and others work like ball type spirit−levels. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 08|Inclinometer Method/B1 Page 286 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 143 HAM US/F SwD 01.12.2007 Inclinometer Method 08|Inclinometer Method/B1 Page 287 FUNDAMENTALS ATA 28 Aircraft Attitude Determination cont. Plumb Method On other aircraft you can attach a plumb in the wheel well of the aircraft and you can read the attitude on a scale below the plumb. The plumb method is the most precise method used to determine the aircraft attitude on ground. On some aircraft you may find only 1 scale on the longitudinal axis. To determine the roll attitude on these aircraft you measure the deflection of the plumb to the aircraft centerline and compare it with the scale. This example shows a roll attitude of approximately 0.8. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 08|Pumb Method/B1 Page 288 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 144 HAM US/F SwD 01.12.2007 Plumb Method 08|Pumb Method/B1 Page 289 FUNDAMENTALS ATA 28 Aircraft Attitude Determination cont. Attitude Monitor Method On modern Airbus aircraft, the attitude is checked with an attitude monitor. This monitor is usually located in the fuselage refueling bay next to the refueling panel. The position of the bubble in relation to the grid pattern on the monitor gives the aircraft attitude. Each square of the grid represents 0.5 of attitude change. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 09|Attitude Monitor Method/B1 Page 290 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 145 HAM US/F SwD 01.12.2007 Attitude Monitor 09|Attitude Monitor Method/B1 Page 291 FUNDAMENTALS ATA 28 FUEL DENSITY DETERMINATION To determine the fuel quantity in a tank using the measuring sticks you need to know 4 parameters. 3 of these you know by now; the aircraft attitude, the measuring stick number and stick reading. You can check the fuel density with a hydrometer. You read the fuel density where the probe cuts through the surface of the fuel sample. The lower part of the probe serves as a thermometer to show the fuel temperature. If a hydrometer is not available, the standard fuel density of 0.8kg/l is used for calculation. Sometimes the density is based on the ISA and related to a fixed volume. It is then called specific gravity. Either density or specific gravity is used for calculation. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 10|Fuel Density Determination/B1 Page 292 Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM FUNDAMENTALS ATA 28 Temperature Reading FOR TRAINING PURPOSES ONLY! Density Reading Figure 146 HAM US/F SwD 01.12.2007 Fuel Density Determination 10|Fuel Density Determination/B1 Page 293 FUNDAMENTALS ATA 28 FUEL QUANTITY DETERMINATION When you have collected all the required parameters as shown on this notepad you use a conversion table to determine the fuel quantity. The conversion tables are either part of the maintenance manual or they are found in a separate document like this Boeing fuel conversion table. In either case, the conversion tables are always a set of many pages which must be read very carefully. We will now explore how to read these tables. First you must be sure that you have found the correct table for the tank you took the reading from. The next parameter to verify on the chart is your recorded pitch attitude. The next parameter to verify is the measuring stick number. With the correct page of the conversion tables in front of you, you locate the column for the recorded roll attitude of 1.5 and then you find your stick reading in the reading column and determine the attitude corrected tank quantity in the roll column. The indicated tank quantity for this aircraft attitude on tank number 2 is 37,801 kg. Note that this quantity is based on a specific gravity of 0.81, so the last thing you need to do now is to correct the determined tank quantity with the actual fuel density. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 11|Fuel Qty Determination/B1 Page 294 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 147 HAM US/F SwD 01.12.2007 Fuel Conversion Table 11|Fuel Qty Determination/B1 Page 295 FUNDAMENTALS ATA 28 Fuel Quantity Determination cont. The correction is done using the density correction diagram. Note that the density correction is only necessary if the actual fuel density differs from the specific gravity given on the chart. The fuel load density correction diagram shows specific gravity correction lines with their respective values. You find your determined indicated fuel load on the left vertical axis, draw a horizontal line to the recorded specific gravity line and from this intersection draw a vertical line to find the corrected fuel load on the lower axis. So, if you want to determine the actual fuel load of a tank, as the first step it is always a good practice to highlight the recorded specific gravity line on the conversion chart. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 12|Fuel Qty Determination/B1 Page 296 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 148 HAM US/F SwD 01.12.2007 Density Correction Diagram 12|Fuel Qty Determination/B1 Page 297 FUNDAMENTALS ATA 28 Fuel Quantity Determination cont. To determine the actual fuel quantity on modern airbus aircraft you need to record the same parameters such as tank number, stick number and stick reading. You determine the aircraft attitude on the attitude monitor and record the grid reference and then locate the conversion table for the recorded stick number and grid reference code in the maintenance manual. Now you have to convert the fuel volume into fuel weight using this conversion chart. First highlight the recorded specific gravity. Then find the fuel volume, in our example 6,450 l, on the table and draw a horizontal line to the highlighted specific gravity line. From the intersection of the fuel volume and the specific gravity line, follow the closest adjacent curve to the left of the chart to find the fuel weight. In our example 6,450 l of fuel with a specific gravity of 0.79 weighs approximately 5,000 kg. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM HAM US/F SwD 01.12.2007 13|Fuel Qty Determination/B1 Page 298 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS MECHANICAL QUANTITY INDICATION SYSTEM Figure 149 HAM US/F SwD 01.12.2007 Fuel Quantity on Airbus 13|Fuel Qty Determination/B1 Page 299 FUNDAMENTALS ATA 28 FUEL SAFETY OVERVIEW You can divide fuel handling safety procedures into three areas such as fire prevention, fire extinguishing and personnel safety. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 01|Overview/A/B1 Page 300 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 150 HAM US/F SwD 01.12.2007 Overview 01|Overview/A/B1 Page 301 FUNDAMENTALS ATA 28 Overview cont. Fire prevention is the elimination of all the sources which create or support a fire. Fire is assisted by inflammable vapor, heat sources and oxygen. So elimination of any one of these sources can prevent fire. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 02|Overview/A/B1 Page 302 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 151 HAM US/F SwD 01.12.2007 Fire Prevention 02|Overview/A/B1 Page 303 FUNDAMENTALS ATA 28 Overview cont. Because oxygen and fuel vapor can not be eliminated, no naked flame and no smoking is allowed during aircraft maintenance and it makes perfect sense that no refueling and defueling takes place during filling or changing of oxygen bottles. To fight any possible fire you must ensure that the correct fire extinguishers are available. You will learn more about fire fighting and the different types of fire extinguishers in the lessons about fire protection in M11.8. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 03|Overview/A/B1 Page 304 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 152 HAM US/F SwD 01.12.2007 Fire Fighting 03|Overview/A/B1 Page 305 FUNDAMENTALS ATA 28 Overview cont. Apart from fire, there are two other main hazards of working with fuel. Fuel vapor inhalation can make you ill or even unconscious and any fuel contact to your skin should also be avoided. Fuel contact destroys the protective film on your skin and eyes. Fuel is also poisonous and should not be swallowed. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 04|Overview/A/B1 Page 306 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 153 HAM US/F SwD 01.12.2007 Fuel Vapor and Contact 04|Overview/A/B1 Page 307 FUNDAMENTALS ATA 28 SAFETY AREAS As you probably realize, fuel vapor comes mainly from the fuel vent tanks or from fuel leaks. You designate a safety area around on aircraft when a high fire hazard exists. This would be during refueling or defueling or at any time when the fuel tanks were open. The limits of the safety area are marked in different ways, colored floor markings are found at the gate. The gate area is always a no−smoking area. The refueling side of the aircraft is kept clear to ensure safe monitoring and a free escape route. The fuel truck has to be positioned to enable a quick escape. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 05|Safety Areas/A/B1 Page 308 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 154 HAM US/F SwD 01.12.2007 Safety Area - Outside 05|Safety Areas/A/B1 Page 309 FUNDAMENTALS ATA 28 Safety Areas cont. You mark the safety areas inside the hangar with posts and barriers. A no−smoking rule is normal inside hangars. Additional warning signs and signal lights alert the hangar crew if the aircraft fuel tanks are open. Refueling in the hangar must be avoided, but if you HAVE TO the entire hangar area will become the safety area. You have seen that the fire hazard with fuel vapors can be reduced by recognizing the safety areas. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 06|Safety Areas/A/B1 Page 310 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 155 HAM US/F SwD 01.12.2007 Safety Area - Hangar 06|Safety Areas/A/B1 Page 311 FUNDAMENTALS ATA 28 INFLAMMABLE FUEL VAPOR & LEAKS Fuel leaks are either caused by refueling malfunctions or by damage to the aircraft. If refueling leaks occur, they would usually be at the vent tank openings. You should be aware that leaks can occur in faulty refueling couplings, refueling hoses and fuel truck components. You must deal with any spilled fuel or fuel leakage immediately. You first stop the leakage flow then add a binding agent to the fuel spillage. You minimize fuel leakage of any kind by ensuring that refueling is not done unattended especially during overwing refueling. You should also be aware that fuel may spray around, if you drain tanks in windy conditions. Fuel leakage may also be caused by damage. Aircraft damage can be caused by the aircraft moving during refueling. So you must ensure that the wheel chocks are in place during refueling. Even with the wheel chocks in place damage to the tanks may occur. This can be caused by any equipment which is located too close to the aircraft as it gets heavier because of the increasing fuel load compressing the shock struts of the landing gears. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 07|Fuel Leaks/A/B1 Page 312 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 156 HAM US/F SwD 01.12.2007 Fuel Leaks 07|Fuel Leaks/A/B1 Page 313 FUNDAMENTALS ATA 28 HEAT SOURCES As mentioned before, no naked flames and no smoking is allowed at the aircraft to reduce the fire hazard, but be aware, that there are many other heat sources near an aircraft which are capable of igniting a fuel air mixture. It should be obvious to you, that refueling is not allowed when the aircraft engines are running. For the same reason no car engine should be operated near or below a vent tank opening. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 08|Heat Sources/A/B1 Page 314 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 157 HAM US/F SwD 01.12.2007 Heat Sources 08|Heat Sources/A/B1 Page 315 FUNDAMENTALS ATA 28 Heat Sources cont. Other heat sources that may inflame a fuel air mixture, are sparks. Conditions that can create sparks on an aircraft can be either electrical switching, HF transmission or weather radar operation by metal parts such as tools being struck together or by electric static discharge. Electric static charges are not visible, and as you probably know by experience, you cannot feel if your body is loaded with a high static charge, you just feel the discharge if it happens in a high energy spark. During refueling electric static charge is created. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 09|Sparks/A/B1 Page 316 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 158 HAM US/F SwD 01.12.2007 Sparks 09|Sparks/A/B1 Page 317 FUNDAMENTALS ATA 28 Heat Sources cont. To prevent any sparks by electric static discharge the fuel truck must be connected to the aircraft by a grounding lead. When working in a fuel tank, you must use special tools which do not create any sparks. These tools are called explosion proof tools. Even walkie−talkies which are used during tank maintenance must be explosion proof. When entering a tank, you have to wear special clothing made of cotton which will not create electric static charges. Avoiding sparks is one of the most important things to prevent a fire. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 10|Avoiding Sparks/A/B1 Page 318 Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Aircraft Grounding for Refueling Fuel Tank Access Tools Fuel Tank Access Equipment Figure 159 HAM US/F SwD 01.12.2007 Avoiding Sparks 10|Avoiding Sparks/A/B1 Page 319 FUNDAMENTALS ATA 28 FUEL TANK ENTERING You must be very careful when entering a fuel tank to protect yourself and your equipment. Cotton tank access clothing protects against sparks tank access socks minimize the danger of damaging internal tank equipment and tank sealers and respirators or full face masks prevent you from inhaling fuel vapor. You can enter the tank without a full face mask only if the tank is considered health safe. Special gas measuring equipment checks the gas concentration inside the tank and alerts the maintenance crew if the gas concentration gets too high. When you use this gas measuring equipment, it must be set up outside the safety area because the equipment is not explosion proof and you must take great care installing the gas measuring probe correctly inside the tank. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 11|Fuel Tank Entering/A/B1 Page 320 Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY FUNDAMENTALS ATA 28 Installation of Gas Measuring Probe FOR TRAINING PURPOSES ONLY! Gas Measuring Equipment Figure 160 HAM US/F SwD 01.12.2007 Tank Entering Equipment 11|Fuel Tank Entering/A/B1 Page 321 FUNDAMENTALS ATA 28 Fuel Tank Entering cont. A health safe tank can only be achieved by sufficient ventilation. Tank ventilation fans and exhaust hoses are used to transport the fuel vapours out of the aircraft tank. For safety reasons, maintenance inside a fuel tank always requires two or more people. To specify the required safety equipment and actions for access to the different tank areas, the tanks are divided into different categories. If the tank is a category 1, it has a direct access door, but you can’t get in completely. This means that access is by head and shoulders only. A category 2 tank has a direct access door and is wide enough for you to gain access for your complete body. A category 3 tank has no direct external access door, but there are internal openings which allow you to get in and they are even wide enough for rescue if necessary. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 12|Fuel Tank Entering/A/B1 Page 322 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 161 HAM US/F SwD 01.12.2007 Tank Entering 12|Fuel Tank Entering/A/B1 Page 323 FUNDAMENTALS ATA 28 Fuel Tank Entering cont. A category 4 tank area is not found on all aircraft. This area can only be entered via internal openings which are not wide enough for rescue personnel in an emergency. To get you out of one of these tanks mechanical cutters would have to be used. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY HAM US/F SwD 01.12.2007 13|Fuel Tank Entering/A/B1 Page 324 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS FUEL SAFETY Figure 162 HAM US/F SwD 01.12.2007 Category ”Four” Tank Area 13|Fuel Tank Entering/A/B1 Page 325 FUNDAMENTALS ATA 28 SUMMARY OF FUEL SYSTEM OPERATION AUTOMATIC REFUELING You probably remember that before you start refueling you must perform 2 tests in order to verify that the system is working correctly. One of the tests, the quantity indicator test, is to see if the quantity system is functioning correctly. The other test you need to perform is the high level test. This test is to check the high level shut-off protection circuits. When you have successfully performed the required tests, you may start to refuel the aircraft in automatic mode to reach the required block fuel quantity. Remember, that first you do your preselection of 16 500 kg and then select the refuel switch position. In automatic refueling mode you just preselect the required block fuel quantity using the decrease/increase selector and then start refueling with the mode selector set to refuel. The fuel control computer calculates how much fuel each tank must carry to meet your needs. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION HAM US/F SwD 01.12.2007 01|Autom Refueling/A/B1 Page 326 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION Figure 163 HAM US/F SwD 01.12.2007 Automatic Refueling 01|Autom Refueling/A/B1 Page 327 FUNDAMENTALS ATA 28 MANUEL REFUELING For manual refueling you must calculate the fuel distribution before refueling. To do so you must know the respective tank capacities. On this aircraft: the inner tank capacity is 33 000 kg the outer tank capacity is 2 900 kg the center tank capacity is 32 550 kg and the trim tank capacity is 4 800 kg. You are to manually refuel this aircraft to 90 000 kg. After calculating the correct fuel distribution you are ready to begin manual refueling. On this refueling control panel are quantity indicators for all the tanks in the center of this panel. Below the indicators you find the refueling valve switches and the mode selector switch and on the upper part of the panel you can see the high level and overflow warning light. After you have performed the high level test you can go on and refuel the aircraft to 90 000 kg using the manual mode. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION HAM US/F SwD 01.12.2007 02|Manual Refueling/A/B1 Page 328 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION Figure 164 HAM US/F SwD 01.12.2007 Manuel Refueling 02|Manual Refueling/A/B1 Page 329 FUNDAMENTALS ATA 28 PRESSURE DEFUELING The next task is to pressure defuel a specific tank on this aircraft. In order to complete this task you need to know the tank capacities. The wing tank capacity is 6 240 kg for each tank and the center tank capacity is 6 600 kg. Due to a faulty automatic refueling system, you ended up with 17 480 kg block fuel instead of the pre−selected 14 000 kg .How much fuel has to be defueled from the center tank to get to the desired block fuel quantity? You have to defuel the center tank to 1 520 kg. The pressure defueling method is preferred on this aircraft. To start defueling, you set the mode selector to DEFUEL XFER. You then turn on both center tank boost pumps, open the cross−feed valve and monitor the center tank fuel quantity. When the required fuel quantity is reached, you switch off the center tank boost pumps, close the cross−feed valve and on the external refueling panel set the mode selector switch to off. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION HAM US/F SwD 01.12.2007 03|Pressure Defueling/A/B1 Page 330 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION Figure 165 HAM US/F SwD 01.12.2007 Pressure Defueling 03|Pressure Defueling/A/B1 Page 331 FUNDAMENTALS ATA 28 FUEL TRANSFER Fuel transfer is similar to pressure defueling, the only difference is that you defuel one tank and refuel another tank. So you switch on the boost pumps of the tank to be emptied and open the crossfeed valve. On the external refueling control panel you open the refueling valves of the tanks that receive the fuel and close the refueling valve of the tank to be emptied. Finally you open the defuel/transfer valve to interconnect the fuel feed system with the refueling system. Another reason for fuel transfer is to equally balance the fuel load after aircraft maintenance. FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION HAM US/F SwD 01.12.2007 04|Fuel Transfer/A/B1 Page 332 FUNDAMENTALS ATA 28 FOR TRAINING PURPOSES ONLY! Lufthansa Technical Training FUEL SYSTEMS SUMMARY OF FUEL SYSTEM OPERATION Figure 166 HAM US/F SwD 01.12.2007 Fuel Transfer 04|Fuel Transfer/A/B1 Page 333 EJAMF M11.10 B1 E TABLE OF CONTENTS FUEL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TYPES OF TURBINE ENGINE FUEL . . . . . . . . . . . . . . . . CHARACTERISTICS OF TURBINE ENGINE FUELS . . WATER IN FUEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 6 12 FUEL STORAGE SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TANK ARRANGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . TANK TYPES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL MOVEMENT DAMPENING . . . . . . . . . . . . . . . . . . . ACCESS TO FUEL TANKS . . . . . . . . . . . . . . . . . . . . . . . . TANK ACCESS PANELS . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TANK VENTILATION SYSTEM . . . . . . . . . . . . . . . . 18 18 24 32 38 40 42 FUEL TANK DRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WATER DRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MANUALLY OPERATED DRAIN VALVES . . . . . . . . . . . . ELECTRICALLY OPERATED DRAIN VALVES . . . . . . . . WATER SCAVENGE SYSTEM . . . . . . . . . . . . . . . . . . . . . FUEL DRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 46 50 54 56 60 FUEL TANK VENT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TANK VENT SYSTEM INTRODUCTION . . . . . . . FUEL TANK VENT SYSTEM OVERVIEW . . . . . . . . . . . FUEL TANK VENT SYSTEM OPERATION . . . . . . . . . . FUEL TANK PRESSURIZATION . . . . . . . . . . . . . . . . . . . . OVERPRESSURE PROTECTION . . . . . . . . . . . . . . . . . . 62 62 64 66 72 74 REFUELING SYSTEM: INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . REFUELING METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL DISTRIBUTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REFUELING SYSTEM ORGANIZATION . . . . . . . . . . . . . REFUELING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 76 82 86 88 REFUELING SYSTEM FUNCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTROL PANELS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTROLS FOR REFUELING . . . . . . . . . . . . . . . . . . . . . CONTROLS FOR REFUELING . . . . . . . . . . . . . . . . . . . . . INDICATIONS FOR REFUELING . . . . . . . . . . . . . . . . . . . POWER SUPPLY FOR REFUELING . . . . . . . . . . . . . . . . 90 90 92 94 98 102 REFUELING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REFUELING SAFETY SHUT-OFF SYSTEMS . . . . . . . . 104 108 REFUELING COMPONENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REFUELING COUPLING . . . . . . . . . . . . . . . . . . . . . . . . . . REFUELING MANIFOLD . . . . . . . . . . . . . . . . . . . . . . . . . . REFUELING VALVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DIFFUSERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 114 120 126 130 FUEL FEED SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PURPOSE OF FUEL FEED SYSTEM . . . . . . . . . . . . . . . FUEL FEED MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . ORGANIZATION OF FUEL FEED SYSTEM . . . . . . . . . . FUEL MANAGEMENT CONTROL PANEL . . . . . . . . . . . FUEL FEED SYSTEM INDICATIONS . . . . . . . . . . . . . . . . FUEL PUMP INDICATION . . . . . . . . . . . . . . . . . . . . . . . . . VALVE INDICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 132 138 144 150 156 158 162 FUEL FEED SYSTEM: FUNCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . MECHANICAL FUEL FEED MANAGEMENT . . . . . . . . . ELECTRICAL FUEL FEED MANAGEMENT . . . . . . . . . . ELECTRICAL FUEL FEED MANAGEMENT . . . . . . . . . . FUEL TRANSFER MANAGEMENT . . . . . . . . . . . . . . . . . FUEL SCAVENGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL RECIRCULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL BOOST PUMP FUNCTION . . . . . . . . . . . . . . . . . . . 168 168 172 174 176 180 184 186 DEFUELING AND FUEL TRANSFER . . . . . . . . . . . . . . . . . . . . . . . . . . PRESSURE DEFUELING . . . . . . . . . . . . . . . . . . . . . . . . . . SUCTION DEFUELING . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TRANSFER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 190 194 196 TRIM TANK SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BASIC PRINCIPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CENTER OF GRAVIVTY DETERMINATION . . . . . . . . . . TRIM TANK SYSTEM FUNCTION . . . . . . . . . . . . . . . . . . SYSTEM ORGANIZATION . . . . . . . . . . . . . . . . . . . . . . . . . TRIM TANK CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . TRIM TANK INDICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 198 198 202 210 212 216 218 Page i EJAMF M11.10 B1 E TABLE OF CONTENTS JETTISON SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ORGANIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTROL PANEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTROLS AND INDICATION . . . . . . . . . . . . . . . . . . . . . OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 220 222 226 228 234 ELECTRICAL FUEL INDICATION AND SENSING . . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL QUANTITY INDICATION . . . . . . . . . . . . . . . . . . . . . FUEL QUANTITY PROBES . . . . . . . . . . . . . . . . . . . . . . . . FUEL CHARACTERISTICS SENSORS . . . . . . . . . . . . . . FUEL LEVEL SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL LEVEL SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TEMPERATURE INDICATION . . . . . . . . . . . . . . . . 238 238 242 244 250 254 256 264 MECHANICAL QUANTITY INDICATION SYSTEM . . . . . . . . . . . . . . . MEASURING STICK ARRANGEMENT . . . . . . . . . . . . . . MEASURING STICK FUNCTION . . . . . . . . . . . . . . . . . . . MEASURING STICK READING . . . . . . . . . . . . . . . . . . . . . AIRCRAFT ATTITUDE DETERMINATION . . . . . . . . . . . . FUEL DENSITY DETERMINATION . . . . . . . . . . . . . . . . . FUEL QUANTITY DETERMINATION . . . . . . . . . . . . . . . . 270 270 272 276 284 292 294 FUEL SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAFETY AREAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INFLAMMABLE FUEL VAPOR & LEAKS . . . . . . . . . . . . . HEAT SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TANK ENTERING . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 300 308 312 314 320 SUMMARY OF FUEL SYSTEM OPERATION . . . . . . . . . . . . . . . . . . . AUTOMATIC REFUELING . . . . . . . . . . . . . . . . . . . . . . . . . MANUEL REFUELING . . . . . . . . . . . . . . . . . . . . . . . . . . . . PRESSURE DEFUELING . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL TRANSFER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 326 328 330 332 Page ii EJAMF M11.10 B1 E TABLE OF FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 16 Figure 17 Figure 18 Figure 13 Figure 20 Figure 21 Figure 22 Figure 14 Figure 15 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 16 Figure 17 Figure 18 Figure 33 Figure 34 Figure 35 Types of Engines Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Main Caracteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water in Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Microbial Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water Concentration Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . Tank Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Main Tanks - Reserve Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Integral Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Integral Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Additinonal or Auxiliary Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . Dampening Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flap/Baffle Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wing Postion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Access Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ventilation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fue Tank Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water Draining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drain Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manually Drain Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direct Drain Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electricallay Operated Drain Valves . . . . . . . . . . . . . . . . . . . . . Water Scavenge System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Water Scavenge Sytem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Drain Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Tank Vent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Vent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Interacts during Maneuvers . . . . . . . . . . . . . . . . . . . . . . . . Fuel Interacts via Wing Up/Down . . . . . . . . . . . . . . . . . . . . . . . Fuel Vent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 Figure 36 Figure 37 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 51 Figure 32 Figure 33 Figure 34 Figure 35 Figure 36 Figure 57 Figure 58 Figure 59 Figure 60 Figure 61 Figure 62 Figure 63 Figure 64 Figure 65 Figure 37 Figure 38 Figure 68 Figure 39 Figure 40 Fuel Tank Pressurization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overpressure/Negative Pressure . . . . . . . . . . . . . . . . . . . . . . . Fueling System/Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gravity Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pressurized Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Load / Fuel Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Control Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controls for Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controls for Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling on Airbus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B747 Refueling Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical power for Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Control Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Shut Off System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Shut Off System (Airbus) . . . . . . . . . . . . . . . . . . . . . Overflow Sensors or Float Switches . . . . . . . . . . . . . . . . . . . . . Refueling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Couplings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Coupling and Nozzle . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Manifold Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Manifold and Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Refueling Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solenoid Controlled Refueling Valve . . . . . . . . . . . . . . . . . . . . . Tank Diffuser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Feed System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU, Horizontal Stabilizer and Fuel Feed System . . . . . . . . . Fuel Recirculation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Feed Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Feed Management B737 . . . . . . . . . . . . . . . . . . . . . . . . . . 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117 119 121 123 125 127 129 131 133 135 137 139 141 Page i EJAMF M11.10 B1 E TABLE OF FIGURES Figure 41 Figure 72 Figure 73 Figure 74 Figure 42 Figure 43 Figure 44 Figure 45 Figure 79 Figure 80 Figure 81 Figure 82 Figure 83 Figure 84 Figure 85 Figure 86 Figure 87 Figure 88 Figure 89 Figure 90 Figure 91 Figure 92 Figure 93 Figure 94 Figure 46 Figure 47 Figure 48 Figure 49 Figure 50 Figure 51 Figure 101 Figure 102 Figure 103 Figure 104 Figure 52 Fuel feed Management on B747 or A 320 . . . . . . . . . . . . . . . . Fuel Feed System Main Components . . . . . . . . . . . . . . . . . . . Transfer Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Fuel Feed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Management Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Individuell Crossfeed Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . Engine Fuel Shut Off Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Feed System Indications . . . . . . . . . . . . . . . . . . . . . . . . . . Boost Pump Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . EICAS Display Low Pressure Indication . . . . . . . . . . . . . . . . . Valve Status System Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Feed-Valve Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transfer Valve Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanical Fuel Feed Management . . . . . . . . . . . . . . . . . . . . . Sequence Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical Fuel Feed Management on Ground . . . . . . . . . . . . . Electrical Fuel Feed Management in Cruise . . . . . . . . . . . . . . Fuel Level Sensing Control Unit . . . . . . . . . . . . . . . . . . . . . . . . In Flight Fuel Transfer ”Trim Tank” . . . . . . . . . . . . . . . . . . . . . . Fuel Scavange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrically Scavenge Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Recirculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Boost Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discription of the Fuel Boost Pump . . . . . . . . . . . . . . . . . . . . . . Defueling A320 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Defuel Transfer Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Suction Defueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manually Fuel Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trim Tank Basic Prinziples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aircraft Trim Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center of Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center of Gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Change of Gravity Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center of Gravity Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trim Tank System Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 145 147 149 151 153 155 157 159 161 163 165 167 169 171 173 175 177 179 181 183 185 187 189 191 193 195 197 199 201 203 205 207 209 211 Figure 106 Figure 107 Figure 108 Figure 109 Figure 53 Figure 111 Figure 112 Figure 54 Figure 114 Figure 115 Figure 116 Figure 117 Figure 118 Figure 55 Figure 56 Figure 57 Figure 122 Figure 123 Figure 124 Figure 125 Figure 126 Figure 58 Figure 128 Figure 129 Figure 130 Figure 131 Figure 59 Figure 60 Figure 134 Figure 61 Figure 62 Figure 63 Figure 138 Figure 139 Figure 140 Components of Gravity Control System . . . . . . . . . . . . . . . . . Components of Gravity Control System . . . . . . . . . . . . . . . . . Trim Tank Manuel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trim Tank Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Jettison System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controls and Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jettison Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jettison Controls on Airbus A340 . . . . . . . . . . . . . . . . . . . . . . Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jettison Termination by Pump Inlets . . . . . . . . . . . . . . . . . . . . ECAM or EICAS Fuel Display . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel System Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity Indication System . . . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity Probe Architecture . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Characteristics Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Level Sensing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Level Sensing System . . . . . . . . . . . . . . . . . . . . . . . . . . . Float Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermistor Type Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Single Point Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Temperature Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Temperature Sensor Installation . . . . . . . . . . . . . . . . . . . . Fuel Temperature Sensor Installation . . . . . . . . . . . . . . . . . . . Measuring Stick Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . Measuring Stick Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manuel Magnetic Level Indicator . . . . . . . . . . . . . . . . . . . . . . . . Manuel Magnetic Level Indicator . . . . . . . . . . . . . . . . . . . . . . . Meassuring Stick Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . Stick Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 215 217 219 221 223 225 227 229 231 233 235 237 239 241 243 245 247 249 251 253 255 257 259 261 263 265 267 269 271 273 275 277 279 281 Page ii EJAMF M11.10 B1 E TABLE OF FIGURES Figure 141 Figure 142 Figure 143 Figure 144 Figure 145 Figure 146 Figure 147 Figure 148 Figure 149 Figure 64 Figure 65 Figure 66 Figure 67 Figure 68 Figure 69 Figure 70 Figure 71 Figure 72 Figure 73 Figure 74 Figure 75 Figure 76 Figure 77 Figure 78 Figure 79 Figure 80 Aircraft Attitude on Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . Attitude Determination Methods . . . . . . . . . . . . . . . . . . . . . . . Inclinometer Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plumb Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Attitude Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Density Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Conversion Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Density Correction Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Quantity on Airbus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fire Prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fire Fighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Vapor and Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Safety Area - Outside . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Safety Area - Hangar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heat Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sparks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Avoiding Sparks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Entering Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tank Entering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Category ”Four” Tank Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Automatic Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manuel Refueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pressure Defueling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fuel Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 285 287 289 291 293 295 297 299 301 303 305 307 309 311 313 315 317 319 321 323 325 327 329 331 333 Page iii
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