APU Flashcards
Max operating altitude for the APU?
43,100 ft (same as the aircraft)
Max altitude for APU bleed air?
22,000 ft
What are the two APU operating modes?
- Attended
- Unattended
When does the APU operate in the unattended mode?
On the ground and when neither engine is running or starting
When the does the APU operate in the attended mode?
When either engine is running or starting, or when the aircraft is in flight.
In the unattended mode, what will most faults will result in?
An immediate shutdown of the APU.
What will happen if an APU fire is detected in the unattended mode?
The APU will automatically shutdown and the APU fire extinguisher bottle will automatically discharge.
In the attended mode, will the APU shut down immediately?
Only certain faults will cause the APU to shut down immediately.
If an APU fire is detected in the attended mode, what will happen?
The APU will shut down immediately, but the APU fire extinguisher bottle will not automatically discharge.
When will the APU LIMIT EICAS message and FAULT light appear?
- High EGT
- High oil temp
- Low oil pressure
