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 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 on the ground will the bottles fire?
Yes
If the APU shuts down automatically due to fire in flight will the bottles fire?
No
At what altitude will the surge control valve open?
17, 000
What is the maximum altitude for APU operation
FL410
What is the maximum altitude for APU start?
FL 370
What is the maximum altitude for APU bleed air extraction?
FL250
The APU will not start if the APU rpm is rotating above what speed on the ground verses in flight?
5% on the ground
12% in flight
If the APU door is open or the door position is unknown with the APU shutdown, what is the limitation?
Flight is restricted to 220 Kts
What is the primary reason for the previous (220 kts) Restriction?
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 Kts restriction with the APU door open?
Yes, turn on the APU
What provides fuel to the APU?
28 VDC pump feeding from the left collector tank
