General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

When is the DC fuel pump activated?

1. When the aircraft is on the ground only

2. When the APU selector is ON and AC power is not available

3. Automatically during all phases of flight

4. Only when fuel levels are critically low

The correct answer is: When the APU selector is ON and AC power is not available

The activation of the DC fuel pump is specifically contingent upon the operational status of the APU (Auxiliary Power Unit) and the availability of AC (Alternating Current) power. When the APU selector is set to "ON" and the aircraft is not receiving AC power, the DC fuel pump activates to ensure that fuel is still delivered to the engines effectively. This is particularly vital for maintaining engine operations during critical phases, such as start-up or when normal AC power is not available, showcasing the importance of redundancy in aircraft systems to enhance safety. The other scenarios described do not accurately represent the operational conditions required for the activation of the DC fuel pump. For instance, it is not limited to ground operations or solely based on fuel levels, as the pump is designed for specific circumstances when other power sources are unavailable, which is why this answer clearly indicates the correct parameters.