Turbine Powered Auxilary Power Units Flashcards
1
Q
- What is the typical relationship between aircrafts auxiliary power unit generator and the engine Driven generator?
A
Identical
2
Q
- Where does the APU fuel supply normally come from?
A
Airplanes main fuel supply
3
Q
- How does the APU rotate during start up?
A
Electric starter
4
Q
- What is the function of an APU air inlet plenum?
A
To stabilize pressure of air before it enters compressor
5
Q
- When operating at high loads, what is the speed of an APU?
A
At or near constant speed regardless of load
6
Q
- What is the effect of the pneumatic power when being used in conjunction with maximum APU shaft power output?
A
Pneumatic loading will automatically modulate to maintain safe EGT
7
Q
- Before shutting down, how would APU cooling be accomplished?
A
Closing the bleed air valve
8
Q
- When is most of the load placed on an APU?
A
Bleed air is opened
9
Q
- What regulates fuel scheduling during APU start and under varying pneumatic bleed and electrical loads?
A
APU fuel control stystem
10
Q
- How is most troubleshooting accomplished on modern APUs?
A
FADEC
11
Q
- What is the primary function of the load compressor on APUs equipped with a free turbine and load compressor?
A
Provide bleed air for pneumatic systems
12
Q
- To prevent rotor seizure shock cooling how long should an APU idle before being shut down?
A
3-5 minutes
13
Q
- What is the function of the APU on a modern transport category aircraft?
A
Provides bleed air for engine starting, air conditioning, and de icing