CRJ 700 Auxiliary Power Unit (APU) Flashcards
What is the primary purpose of the APU?
The primary purpose of the APU is to provide electrical power
Name some things that would cause the APU to automatically shutdown on the ground or in flight
- Overspeed, >106%
- Loss of overspeed protection
- Loss of speed sensor signals
- No APU rotation
- No APU lightoff
- Slow start
- No Acceleration
- Speed fallback
- APU fire/emergency
- Loss of air inlet
- APU door failure
- Uncommanded door closure
- ECU internal failure
- Loss of DC power
Will the APU shutdown on the ground due to high oil temp or low oil pressure?
Yes
Will the APU shutdown in flight due to high oil temp or low oil pressure?
No
If the APU shuts down automatically due to fire in flight will the bottle fire?
No
At what altitude will the surge control valve open?
17,000’
If the APU shuts down automatically due to fire on the ground will the bottle fire?
Yes
The APU will not start if the APU rpm is rotating above what speed not he ground vs in flight?
5% on the ground, and 12% in flight
If the APU door is open or the door position is unknown with the APU shutdown, the aircraft is limited to 220 knots. Why?
To prevent the APU from wind-milling without the proper lubrication, and to ensure the APU rpm remains below 12% in the event it becomes necessary to start the APU in flight
Is there a way around the 220 knots restriction with the APU door open?
Yes. Normal speeds can be used if the APU is running
What provides fuel to the APU?
A dedicated 28 VDC pump feeding frost he left collector tank
If the APU fuel pump fails will the APU continue to operate?
Yes, but it cannot be restarted without the pump
What is the purpose of the Load Control Valve (LCV)?
The LCV varies pneumatic load to ensure electrical power and 45 psi in the manifold
Can APU bleed air be used by the anti-ice system?
No
What is the minimum battery voltage for APU start?
22 volts
