APU System
NOTE
This is a stub page. Full system description pending ingest of FCOM Chapter 9.
Overview
The Auxiliary Power Unit (APU) is a small gas turbine engine in the tail section that provides electrical power and bleed air independently of the main engines.
Key Functions
- Electrical power: Powers aircraft electrical buses on the ground and in flight
- Bleed air: Provides pneumatic power for engine start, air conditioning
- In-flight backup: Can be started in flight for emergency power/bleed
Limitations
- Start attempts: Maximum 3 within 60 minutes
- Maximum operating altitude for bleed air: check FCOM
- APU fire protection: single-bottle fire extinguisher system