What automatic shutdowns are available on the ground, but not available in flight?

What automatic shutdowns are available on the ground, but not available in flight?

• A. APU Fire (shutdown only, no extinguisher)
• B. High oil temperature
• C. Low oil pressure
• D. Low oil pressure (LOP) switch failed

Answer: (A)

On the ground, certain protections are configured to act automatically to protect equipment when the aircraft is in a non-operational state. The APU fire protection is one of those: if a fire is detected in the APU while the airplane is on the ground and the APU is running, the system will automatically shut the APU down to isolate the fire. Importantly, this automatic action is shutdown-only on the ground—the system does not automatically discharge the APU fire extinguisher in that ground scenario. In flight, the APU isn’t normally in operation in the same way, and the automatic ground-specific shutdown behavior isn’t active as a flight function. The other items involve engine conditions or sensor faults that can affect operations in flight or under normal fault management, so they aren’t ground-only automatic shutdowns.

On the ground, certain protections are configured to act automatically to protect equipment when the aircraft is in a non-operational state. The APU fire protection is one of those: if a fire is detected in the APU while the airplane is on the ground and the APU is running, the system will automatically shut the APU down to isolate the fire. Importantly, this automatic action is shutdown-only on the ground—the system does not automatically discharge the APU fire extinguisher in that ground scenario. In flight, the APU isn’t normally in operation in the same way, and the automatic ground-specific shutdown behavior isn’t active as a flight function. The other items involve engine conditions or sensor faults that can affect operations in flight or under normal fault management, so they aren’t ground-only automatic shutdowns.