In flight, what does the APU automatic fire protection provide?

In flight, what does the APU automatic fire protection provide?

• A. Automatic shutdown of the APU, but not automatic discharge of the fire bottle
• B. Automatic discharge of the fire bottle
• C. Manual discharge option
• D. No protection

Answer: (A)

When an APU fire is detected, the system is designed to shut the APU down automatically. This automatic shutdown stops fuel flow and isolates the APU to prevent the fire from growing. However, the extinguishing bottle is not released automatically from this protection; its discharge is a crew action controlled via the APU fire handle and related switches. So, in flight, the automatic fire protection provides automatic shutdown of the APU, but not automatic discharge of the fire bottle. Manual discharge remains available if the crew decides to extinguish the fire.

When an APU fire is detected, the system is designed to shut the APU down automatically. This automatic shutdown stops fuel flow and isolates the APU to prevent the fire from growing. However, the extinguishing bottle is not released automatically from this protection; its discharge is a crew action controlled via the APU fire handle and related switches. So, in flight, the automatic fire protection provides automatic shutdown of the APU, but not automatic discharge of the fire bottle. Manual discharge remains available if the crew decides to extinguish the fire.