FAA Ground School Practice Test

When is the auxiliary electric driven fuel pump used in aircraft equipped with fuel pumps?

1. During startup

2. In the event the engine-driven fuel pump fails

3. For maintaining fuel pressure

4. When altitude increases

The correct answer is: In the event the engine-driven fuel pump fails

The auxiliary electric driven fuel pump is primarily utilized in aircraft as a backup mechanism in case the engine-driven fuel pump fails. This redundancy ensures that fuel continues to be supplied to the engine to maintain its operation, which is critical for flight safety. The auxiliary pump is particularly important during critical phases of flight and helps prevent engine failure due to fuel starvation. While the electric fuel pump may have some role in other situations, such as assisting during startup or maintaining pressure, its main designed purpose is to function as a safety feature in the event of a primary fuel pump failure. Therefore, understanding this role clarifies why the focus is specifically on its use during emergencies related to pump malfunction.