AVM 147 - Airframe Fuel Systems

1. Inspect, check, service, troubleshoot, and repair aircraft fuel systems.
   1. Explain the reason why internal baffles are designed into metal type fuel tanks, also where fuel tanks sumps are located in fuel tanks.
   2. List requirements as to tank fuel strainers and the purpose and markings as required on the filter cap or immediately adjacent to the filler opening of a fuel tank.
   3. Describe requirements for venting a fuel tank, and what may occur if the vent is obstructed, if two or more fuel tanks may simultaneously supply fuel to an engine
   4. Explain the requirements for interconnected fuel vents and explain test pressure procedures after a fuel tank repair
   5. Identify methods as to manner in which way metal type fuel tanks are anchored or attached to the airplane structure.
   6. Describe why fuel tanks should be installed so that fuel loads are distributed over a wide area rather than concentrated at a local point, also why chafing and vibration problems may be present when installing separate type fuel tanks, and some problems g
   7. Explain how flexible bladder type fuel tanks are attached to the structure of the airplane
   8. Describe reasons for topping a fuel tank rather than permitting the tank to remain in a partially filled condition
   9. Give reasons why fuel selector valves are placard or marked to indicate direction of flow or method of operation, requirements for cross feed valves, as detent or stop position to import a “feel” to the valve position.
   10. Describe the operation of a wobble pump
   11. List factors that contribute to vapor locking of fuel pump
   12. Describe a submerged type fuel boost pump. Explain how booster pumps are used when starting an engine
2. Repair aircraft fuel systems components
   1. Repair fuel tanks
   2. Describe precautions and procedures that are necessary when cleaning a fuel tank prior to accomplishing repair to the tank
   3. Identify publications that will provide information pertaining to the repair of the particular type of tank used in the airplane, also to define test pressures and procedure to be following when testing a repaired fuel tank
   4. Explain position of the main system fuel strainer in respect to other components in the fuel system
   5. Provide publications that would provide information and instructions for servicing the screens in the fuel system
   6. Describe functions and requirements of the selector valves and the operation and placarding of an “on-off” valve
   7. Describe general conditions that dictate the minimum size of fuel lines that may be approved for an airplane
   8. List regulations that govern the routing and location of fuel lines in elation to the electrical cables in the airplane
   9. Provide publications that would give information regarding repair of damaged fuel lines
3. Inspect and repair fluid quantity indicating systems
   1. Recognize fuel quantity indicators
   2. Explain why fuel quantity must be available to the pilot at all times.
   3. Describe the accuracy of float type gauges and electrical quantity gauges, if the altitude of the airplane affects the indicated fuel quantity.
   4. Describe corrections that are usually made in the indicating system.
   5. Explain why the fuel quantity is by weight rather than by gallons, explain why most large, multi-engined airplanes have remote indicating fuel quantity systems
4. Inspect, check and repair pressure fueling systems.
   1. Describe the operation of the pressure fueling system.
   2. List precautions that must be observed before attaching the fueling nozzle to the airplane
   3. Explain precautions when pressure fueling or over-wing system regarding static grounding
   4. Describe the pilot valve in a pressure fueling system and what is its function
   5. Describe the over-pressure safety devices and its function
5. Perform fuel management transfer, and defueling
   1. Describe how fuel management may be used to maintain the center of gravity of an operating airplane within closely defined limits.
   2. Explain the advantage of maintaining the center of gravity at a specific point.
   3. Reference publications a mechanic would use to determine the procedure for transferring fuel
   4. Describe how fuel flow is maintained within the fuel transfer system of an airplane
   5. Explain the purpose of providing for cross feed of fuel in an airplane, also hazards involved in cross feeding fuel
   6. Describe the hazards associated with defueling, also the importance of static grounding the airplane and defueling truck