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

What is an indicator that a fault has occurred with the backup generator?

1. The main generator functions properly

2. The backup generator switch is ON

3. The BACKUP GEN "OFF" light is illuminated

4. The APU smoke detector is activated

The correct answer is: The BACKUP GEN "OFF" light is illuminated

The indicator that a fault has occurred with the backup generator is represented by the illumination of the BACKUP GEN "OFF" light. This light serves as a warning signal that the backup generator is not functioning as intended and is in an inactive or off state. In a normal operation, the backup generator should be ready to engage automatically when the main generator fails, so the activation of this warning light is critical for flight safety. In contrast, if the main generator is operating correctly, it does not provide any insight into the condition of the backup generator. Similarly, the state of the backup generator switch being ON does not confirm that the generator is functioning; it merely indicates that the circuit is closed. Lastly, the activation of the APU smoke detector is related to a potentially different issue involving the auxiliary power unit and does not directly pertain to the status of the backup generator itself. Therefore, the BACKUP GEN "OFF" light becoming illuminated is the most reliable and specific indicator of a fault occurring with the backup generator.