FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationMedium
A twin-engine aircraft experiences a right engine failure in cruise flight. The pilot opens the fuel crossfeed valve. What is the primary function this action performs?
- AIt shuts off fuel supply to the failed engine to prevent a fire
- BIt transfers fuel directly between the left and right tanks to balance weight
- CIt increases fuel pressure to the operating engine's fuel pump
- DIt allows the operating (left) engine to draw fuel from either fuel tank, including the failed engine's tank
Show answer & explanationAnswer & explanation
Correct answer: D. It allows the operating (left) engine to draw fuel from either fuel tank, including the failed engine's tank
A crossfeed system allows any operating engine to be supplied fuel from any tank, which is especially useful after an engine failure so the fuel remaining in the inoperative engine's tank isn't wasted and lateral fuel imbalance is minimized. It does not directly transfer fuel between tanks or act as a fire shutoff.
Why the other options are wrong
- A. Fuel shutoff to the failed engine is handled by the firewall shutoff valve, a separate system.
- B. Crossfeed supplies an engine from another tank; it does not directly move fuel tank-to-tank for weight balance alone.
- C. Crossfeed reroutes fuel source, it does not boost pump pressure.
Fuel Crossfeed System
A fuel system arrangement on multiengine aircraft that allows any engine to draw fuel from any tank, most commonly used during single-engine operation.
- Balances fuel usage after an engine failure
- Prevents stranding usable fuel in the inoperative engine's tank
- Distinct from firewall shutoff valves used to isolate a failed/fire-affected engine
Memory trick: Crossfeed lets the healthy engine 'borrow' fuel from its sick twin's tank.