FAA Aviation Mechanic Airframe (AMA)Fuel, Cabin and Ice Control SystemsEasy
A student pilot asks a mechanic to explain the fuel selector valve positions on a high-wing single-engine trainer equipped with a four-position (LEFT, RIGHT, BOTH, OFF) fuel selector valve. Which position is normally selected for takeoff and landing?
- ALEFT
- BRIGHT
- COFF
- DBOTH
Show answer & explanationAnswer & explanation
Correct answer: D. BOTH
Selecting BOTH draws fuel evenly from both tanks and prevents fuel unporting during the steep pitch and bank attitudes encountered in takeoff and landing maneuvers, as specified in most POHs.
Why the other options are wrong
- A. Using a single tank risks unporting the fuel outlet during maneuvering flight with low fuel.
- B. Same unporting risk applies to selecting only the right tank.
- C. OFF would starve the engine of fuel and cause an immediate power loss.
Fuel Selector Valve
A valve that allows the pilot to select which fuel tank(s) supply the engine, typically with LEFT, RIGHT, BOTH, and OFF positions on light aircraft.
- BOTH is used for takeoff and landing to prevent unporting
- OFF is used for shutdown or maintenance
- Individual tank positions are used in cruise to balance fuel load
Memory trick: BOTH for takeoff and landing keeps you steady, no matter how you're banking or heading.