Turbine powered auxiliary power units Flashcards
What is the typical relationship between an aircraft auxiliary power unit generator and the engine driven generator
They are identical
Where does the APU fuel supply normally come from
The aircraft main fuel supply
How is the APU rotated during start up
And electrical starter
What is the function of an APU air inlet Plenum
Stabilize the pressure of the air before it enters the compressor
When operating a high loads, what is the speed of the APU
Remains at or near rated speed regardless of the load condition
What is the effect of pneumatic power when being used in conjunction with maximum APU shaft power output
The pneumatic loading will be automatically modulated to maintain a safe EGT
Before shut down, how Would an APU Cooling be accomplished
By closing the bleed air valve, those removing the load
When is Most of the load placed on an APU
When the bleed air is opened
What regulates fuel scheduling during APU start and under varying pneumatic bleed and electrical loads
Fuel scheduling is maintained automatically by the APU fuel control system
How is most troubleshooting accomplished on a modern APU
By gathering information from the FADEC
What is the primary function of the load capacitor on an APU Equipped it with a free turbine and load compressor
To provide bleed air for aircraft pneumatic systems
To prevent rotor seizure” shock cooling” How long should an APU idol before being shut down
3 to 5 minutes
