Engine Change 3. Give an example of a common task that must be performed when removing and replacing an aircraft engine. After the engine has been secured to an engine stand, all covers must be removed from the points where the engine was sealed or closed with ventilatory covers, such as the engine breathers, exhaust outlets, and accessory mounting-pad cover plates. As each cover is removed, inspect the uncovered part of the engine for signs of corrosion. Reference: FAA-H-8083-32 Volume 2 Pg 8-4 6. Explain “QECA” in regard to removing and replacing an engine? The QECA is essentially a powerplant and the necessary accessories installed in the engine. Commercial operators, whose maintenance operations require the most efficient and expeditious replacement of aircraft engines, usually rely on a system that utilizes the quickengine-change assembly (QECA), also sometimes referred to as the engine power package. Reference: FAA-H-8083-30 Volume 2 Pg 8-3 9. Describe the inspections performed on the following Engine Nacelle- The engine nacelle must be cleaned thoroughly before it is inspected. Inspect the complete engine nacelle for condition of the framework and the sheet-metal cowling and riveted plates that cover the nacelle. The engine mounting frame assembly should be checked for any distortion of the steel tubing, such as bends, dents, flat spots, corrosion, or cracks. Use the dye penetrant inspection method to reveal a crack, porous area, or other defects. Engine Mounting Bolts- The engine mounting bolts are usually checked for condition by magnetic particle inspection or other approved process. While the bolts are removed, the bolt holes should be checked for elongation caused by the movement of an improperly tightened bolt Electrical Wiring- Check the outer surface of all exposed electrical wiring for breaks, chafing, or other damage. Also, check the security of crimped or soldered cable ends. In addition, carefully inspect connector plugs for overall condition. Any item that is damaged must be repaired or replaced, depending on the extent of the damage. Tubing- Before installing an engine, inspect all tubing in the nacelle for dents, nicks, scratches, chafing, or corrosion. Check all tubing carefully for indications of fatigue or excessive flatness caused by improper or accidental bending. Hoses- Thoroughly inspect all hoses used in various engine systems. Weather checking (a cracking of the outside covering of the hose) sometimes penetrates to the hose reinforcement. Replace any length of hose that shows indications of the cover peeling or flaking or has exposed fabric reinforcement. Replace a hose that shows indications of excessive cold flow. Control Rod- Always replace a control rod if it is nicked or corroded deeply enough to affect its strength. If the corrosion cannot be removed by rubbing with steel wool, the pitting is too deep for safety. Pulleys- On older aircraft, check the pulleys in the control system for freedom of movement. It is easy to spot a pulley that is not turning freely, for both it and the cable are worn from the cable sliding over the pulley instead of rolling free. The bearings of a pulley may be checked by inspecting the pulley for excessive play or wobble with the tension removed from the cable. Cable- The cable must also be inspected for corrosion and broken strands. Locate any broken strands by wiping the cable with a cloth. Bonding- Check bonding for fraying, loose attachment, and cleanness of terminal ends. The electrical resistance of the complete bond must not exceed the resistance values specified in the applicable manufacturer’s instructions. Exhaust Stacks- Inspect the exhaust stacks, collector ring, and tailpipe assembly for security, cracks, or excessive corrosion. Depending on the installation, these units, or parts of them, may be mounted on the engine before it is installed in the aircraft. Air Ducts- Check all air ducts for dents and for the condition of the fabric or rubber anti-chafing strips at the points where sections of duct are joined. The dents may be pounded out; the anti-chafing strips should be replaced if they are pulled loose from the duct or are worn to the point at which they no longer form a tight seal at the joint. Oil System- Thoroughly inspect the engine oil system and perform any required special maintenance upon it before installing a replacement engine. If an engine is being changed at the end of its normal time in service, it is usually necessary only to flush the oil system; however, if an engine has been removed for internal failure, usually some units of the oil system must. Reference: FAA-H-8083-32 Volume 2 Pg 8-6 14. Before starting the engine removal, what fire safety equipment should be located? First, make sure that there are enough fire extinguishers near at hand to meet any possible emergency. Check the seals on these extinguishers to be sure the extinguishers have not been discharged. Reference: FAA-H-8083-32 Volume 2 Pg 8-7 17. Explain the process to draining the engine. Place a large metal pan (drip pan) on the floor under the engine to catch any spilled mixture or oil. Next, secure a clean container in which to drain the oil or corrosion-preventive mixture. Place the container beneath the engine, open the drain valve, and allow the oil to drain. All valves, drains, and lines must remain open until the oil system has been completely drained. After draining the oil, reinstall all drain plugs and close all drain valve. Reference: FAA-H-8083-32 Volume 2 Pg 8-7 20. What must be done to engine fluid lines after disconnections and draining. After the lines have drained, they should be immediately plugged or covered with moistureproof tape to prevent foreign matter from entering them, as well as to prevent any accumulated fluid from dripping out. Reference: FAA-H-8083-32 Volume 2 Pg 8-9 21. What has to be accomplished before freeing the engine from its attaching point? Before the engine can be freed from its attachment points, a sling must be installed so the engine’s weight can be supported with a hoist when the mounting bolts are removed. Reference: FAA-H-8083-32 Volume 2 Pg 8-9 24. What must be accomplished just prior to removing the engine mount attaching hardware? If bolts must be removed from the mount attachments, be sure the engine is under control before doing so. If the bolts are to remain in the mount attachments, the hoist can be gently maneuvered upward or downward as necessary after all the nuts have been removed. Reference: 8-10 29. Why should the hoist support the engine weight when torqueing the Engine mounting hardware? The nuts on the engine mount bolts must be tightened to the torque recommended by the aircraft manufacturer. While the nuts are being tightened, the hoist should support the engine weight sufficiently to allow alignment of the mounting bolts Reference: 8-10 32. How are leaks checked on ducts after reconnection to the engine? The duct systems of some aircraft must be pressure checked for leaks. This is done by blocking the system at one end, supplying compressed air at a specified pressure at the other end, and then checking the rate of leakage. Reference: 8-11 35. What are causes for rejecting a hose clamp? A clamp that is badly distorted or materially defective should be rejected. Material defects include extremely brittle or soft areas that may easily break or stretch when the clamp is tightened. Reference: 8-11 39. What response are each control adjusted to? All engine controls must be accurately adjusted to ensure instantaneous response to the control setting. Reference: 8-11 46. What are 2 indications that bleeding the fuel has occurred? After ensuring the fuel shutoff and main fuel tank valves are open, turn on the fuel boost pump 8-14 Figure 8-13. Cowling removed and stored out of the way. until there are no traces of preservative oil in the fuel being pumped through the system. The passage of air is indicated by the absence of air mixed in the fuel emerging from the end of the hose submerged in the container of fuel. Reference: 8-14 49. Describe the checks for a pitch changing propeller after engine replacement? A propeller whose pitch-changing mechanism is electrically actuated may be checked before the engine is operated. Propellers whose pitch-changing mechanisms are oil actuated must be checked during engine operation after the normal operating oil temperature has been reached. In addition to checking the increase or decrease in rpm, the feathering cycle of the propeller should also be checked. Reference: 8-14 53. Explain the attachment of the engine to the aircraft? The installation procedures are essentially the reverse of the removal procedures. Move the QECA straight back into the nacelle structure and align the mount bolt holes and the firewall. Start all the bolts before torquing. With all the bolts started, and using the correct torque wrench adapter, tighten the mount bolts to their proper torque. Remove the sling and install the access covers at the lift point. Using the reverse of the removal procedures, connect the various lines and connectors. New O-ring seals should be used. The manufacturer’s instructions should be consulted for the proper torque limits for the various clamps and bolts. After installation, an engine runup should be made. In general, the runup consists of checking proper operation of the powerplant and related systems. Several functional tests are performed to evaluate each phase of engine operation. The tests and procedures outlined by the engine or airframe manufacturers should he followed. Reference: 8-23
