FUEL
GENERAL
The Fuel Feed System consists of two independent systems, one for each engine, interconnected
by a cross feed line. The Fuel System ensures a proper fuel supply to the engines and the APU
under all operating conditions. Refueling and defueling operations can be done either by
pressure or by gravity.
Approved Fuels are:
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Jet A; Jet A1; JP8
The Fuel System consists of:
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Tanks
o Wing Tank
o Collector Tanks
o Wing Vent Tanks
Manifolds and Valves
o Check Valves
o Fueling System
o De-fueling System
o Shutoff Valves (SOV)
Pumps
o Electric Fuel Pumps
o Transfer Ejector Pumps
Control Panel
Indicators and Warnings
FUEL TANKS
The Wing Tank's capacity is 5500 lbs. Total capacity is 11100 lbs. The maximum fuel imbalance
is 800 Lbs. between Wing Tanks.
There is a Collector Tank near the wing root which contains three Electric Pumps. The Collector
Tank has Flapper Valves which keep the Electric Pump inlets submerged in fuel. One Ejector
Pump in each wing keeps the Collector Tank full using motive flow fuel from an Electric Pump.
During maneuvers, one of the wing's ribs is partially CLOSED to restrict excessive fuel movement
in the tank. When a wing is down, the Flapper Valves prevent fuel from returning to the Wing
Tank.
There are Vent Tanks in each wing tip that collect fuel when the wing is down and returns it to the
Wing Tank once the maneuver is over and the wing is in a more level condition. The Wing Vent
Tank connects to the Wing Tank by two Float Valves. One Float Valve is OPEN at all times.
There are NACA air intakes under each wing to ventilate the Vent Tank to equalize pressures and
prevent Wing damage.
FUEL SYSTEM CROSSFEED:
The XFEED knob is located on the Fuel Control Panel. It has priority over the PUMP PWR knob.
The XFEED knob isolates tank to engine fuel flow during normal operations. When cross-feed is
desired, the XFEED knob is selected to the Wing Tank with the “low” amount of fuel. It will OPEN
the Cross-feed Valve and will de-energize the Electric Pump(s) in the Wing Tank selected.
Check/Relief Valves in the Pressure Lines:
 Prevent fuel from transferring between Tanks during cross-feed operations
 Permit pressure relief after engine shutdown
 Permit pressure relief if the fuel temperature rises to unacceptable levels.
The APU is normally fed from the RIGHT side.
During Takeoff and Go Around the Cross-feed Selector MUST be OFF.
FUEL SYSTEM SHUTOFF VALVE (SOV)
A Shutoff Valve (SOV) is provided to stop fuel to the engine when FIRE HANDLE is pulled.
ELECTRIC PUMPS
There are three Electric Pumps in the Collector Tank. The Fuel Control Panel has knobs and
selectors to select and power the Electric Pumps. Pumps A and B are powered by the Essential
Bus. Pump C is powered by the DC Bus. The selected pump is alternated every flight leg.
An engine driven fuel pump will provide suction feed if the electric pumps are not
available, but it is limited to a 25,000 ft. altitude.
If the fuel pressure in the engine inlet drops below 6.5 PSI (the selected pump has failed) the
remaining two pumps switch ON automatically. They will cycle (the switching relays can be heard
in the cockpit) until the pilot de-selects the failed pump, and selects one of remaining pumps to
operate continuously. Each Electric Pump has a check valve to prevent fuel from returning to the
other pumps when it is NOT operating. In the case of a loss of electrical power to all the Electric
Pumps, there is a fuel line connected through a check valve to the pressure line which permits
the engines to operate by suction feeding for the engines.
If an Electric Pump is deferred, the usable fuel in that Wing Tank must be reduced by 365 lbs.
CAUTION:
Do NOT let the Electric Pumps run dry.
NOTE: During Takeoff and Go Around -- one Pump in each Tank is required to supply each
engine and the APU. In all other phases of flight, one Pump in cross-feed operation is sufficient
to supply both engines and the APU.
FUEL SYSTEM SENSING
The Fuel Low Level Sensors are installed in both Wing Tanks. The Fuel Temperature Sensor is
installed in the LEFT Wing Tank. The Fuel Pressure Sensors are located at the Engines and
APU. They are responsible for activating the Electric Pumps and alerting EICAS of Low
Pressure. Fuel quantity is also repeated on the EICAS and Fueling Panel.
CAUTION:
Pilots must primarily use EICAS and MFD fuel information. All FMS fuel
information is advisory only.
Magnetic measuring sticks are provided under the wing for directly measuring the fuel quantities.
The aircraft must be level, and the measurements must begin from the outboard measuring stick.
A dedicated MFD Fuel Page displays system configuration, fuel quantity, fuel temperature and
problems.
PRESSURIZED REFLUELING
The wing tanks may be gravity filled through over wing filler caps or by pressure refueling. The
refueling panel in the right wing-to-fuselage fairing allows pressurized refueling/defueling
operations. Pressurized refueling operations require the Refueling System to be energized. This
can be done by either NORMAL (DC Bus 1) aircraft energizing through the APU, GPU, a running
engine driven generator, or battery power; or by selecting BATTERY (Hot Bus 1) on the refueling
panel’s power selection switch. Refueling pressure range is 35-50 PSI
Aircraft equipped with a High Level Exceeding Indication System (HLEIS) will identify an
automatic refueling shutoff failure. One High Level Sensor (HLS) in each wing tank will sense
when the fuel level in the failed tank exceeds the maximum quantity approved for that tank and it
will advise the refueling operator by illuminating a red "STOP RFL" light on the refueling panel for
the failed tank. The operator should stop the refueling operation immediately to prevent fuel
spillage through the vent valve. Maintenance personnel should be called to remove the extra fuel
from the associated tank.
DEFUELING
Pressure de-fueling is performed by using the Electric Pumps installed in the tanks. The defueling valve must be opened from the Refueling Panel at the wing. Pressurized defueling can
only be performed with the aircraft energized. The power selection switch on the refueling panel
does not work for defueling.
Pressurized defueling uses the same adapter as pressure refueling. Pressurized defueling can be
performed using the electric fuel feed pumps installed in the tanks or by suction (4 psi maximum)
from an appropriate external source. Selecting the defueling switch to OPEN will open the
defueling shutoff valve and allow defueling operations. The left tank can be defueled by turning
the crossfeed knob to LOW2.
CAUTION
Do not run the electric pumps if the fuel quantity in each tank is below 54 lb.
Complete gravity defueling may be achieved by using the drain valve and by opening the
associated gravity refueling cap. Partial gravity defueling can be done through the dump valves
located on the wing under skin near the wing root.
FUEL 1 (2) LO LEVEL
Fuel remaining in associated tank has reached a level sufficient for about 30 minutes of flight
(500 lbs.)
E 1 (2) FUEL LO PRESS
Fuel pressure in associated engine inlet is below 6.5psi.
FUEL TANK LO TEMP
Fuel temperature inside left tank is equal to or below –40C.
FUEL XFEED FAIL
A disagreement between cross-feed valve and knob positions has occurred or power supply has
been lost.
FUEL IMBALANCE
Fuel quantity in one tank differs by 800 lbs from the other tank. Message is removed when
difference decreases below 100 lbs.
APU FUEL LO PRESS
Fuel pressure in APU inlet is below 6.5psi with APU Master Selector Knob is set to ON.
E 1 (2) FUEL SOV INOP
Associated shutoff valve is not operating properly (not fully open or not fully closed).
APU FUEL SOV INOP
Associated shutoff valve is not operating properly (not fully open or not fully closed).
E 1(2) FUEL SOV CLSD
Associated engine fuels shutoff valve is closed (FIRE HANDLE)
APU FUEL VALVE CLOSED
APU fuel shutoff valve is closed. Message remains for 10 seconds after APU master knob is set
to the OFF position. If the valve has been commanded to close through the APU FUEL
SHUTOFF button, or the APU FIRE EXTG button, the message will be presented continuously.
FUEL CROSSFEED OPEN
Cross-feed valve is open