APU Flashcards
Where does the APU supply power to?
28VDC R Main feeder bus
Where is APU fuel provided from?
Left tank collector bay
What is the current limit of the APU starter/gen?
300amps
How long must be waited between APU start attempts?
2 minutes - ESU start circuits are inhibited.
How is the APU load monitored?
Select Gen 2 and. Press ‘DC Load Meter’
Can the APU be operated airborne?
No, the PSEU through the WOW sensors detects and signals for an APU shutdown.
Where is the APU fire detection/extinguishing system powered from?
R essential (28VDC)
If a fire or overheat condition is sensed, what occurs?
APU shutdown and red FIRE warning light on the fire protection panel & APU caution light.
How long is the delay between a fire/overheat and fire bottle discharge?
15 seconds - can be manually triggered.
How is it indicated that the fire bottle has been discharged?
External - The yellow disc will be discharged.
Internal - Yellow bottle light on APU panel goes out. Fault light illuminates, indicating a fire extinguisher pressure loss.
What does the external red disk indicate?
Thermal discharge, bottle contents dumped overboard.
Is the APU a variable or constant rpm gas turbine?
Constant RPM
Where does the starting power for the APU come from?
Right 28VDC main feeder bus
What does the APU bleed air supply?
The bleed air supply duct upstream of the A/C pack and de-ice system.
Can APU and external DC power the aircraft system in parallel?
No, GCU or APU. However, APU and engine DC gens operate in parallel.
