In flight, what does the APU DOOR light indicate when illuminated?

In flight, what does the APU DOOR light indicate when illuminated?

• A. APU door is not in flight position
• B. APU door is not in ground position
• C. APU door is open in flight
• D. APU door is closed in flight

Answer: (A)

In flight, the APU intake/door must be in the flight position to provide proper airflow and minimize drag. When the APU DOOR light is illuminated, it indicates the door is not in that flight position. This means there’s a mismatch between the commanded door position and the actual door position, signaling a fault in the door mechanism or its position sensor. It isn’t just about being open or closed in flight—the warning flags that the door isn’t where it should be for flight, which could require checking or cycling the system and possibly maintenance.

In flight, the APU intake/door must be in the flight position to provide proper airflow and minimize drag. When the APU DOOR light is illuminated, it indicates the door is not in that flight position. This means there’s a mismatch between the commanded door position and the actual door position, signaling a fault in the door mechanism or its position sensor. It isn’t just about being open or closed in flight—the warning flags that the door isn’t where it should be for flight, which could require checking or cycling the system and possibly maintenance.