APU Flashcards
1
Q
APU gas turbine generator
- what kind of power does it supply
- limitation on bleed air
- how is it controlled
- limitation while deicing
A
- DC Power - 28vDC, 400 amps (ground operations only)
- Provides Bleed Air for “Air Conditioning Packs” (ground operations only)
- Controlled by its own FADEC
- Can NOT de-ice with APU ON (on ground)
2
Q
APU Fuel Supply
- where is fuel fed from
- what button opens the APU fuel sov and when will it close
- the APU fuel sov will close automatically if any of the following occur (7)
A
- Fuel is fed from the LEFT wing fuel collector bay
- APU fuel shutoff valve OPENS when the APU PWR switchlight is pushed and CLOSES when the APU is shut down
- The APU fuel shutoff valve will automatically close if any of the following should occur:
• The PWR switchlight is pushed off
• An APU fire is detected
• EXTG switchlight on the APU section of the Fire Protection Panel is pushed
• APU FIRE TEST button is pushed
• Aircraft becomes airborne while the APU is still running
• An APU fault is detected
• Starter-Generator overheats (the GEN OHT advisory light illuminates)
3
Q
APU Electrical System
- what voltage is the generator and where is it mounted
- what power is needed for a start
- to what % will the started remain engaged
A
- 28vDC Generator mounted on the APU Gearbox
- APU start requires either aircraft battery power or an external DC power source
- Starter mode remains engaged until the APU reaches 50% operating speed
4
Q
APU bleed air
- Provides bleed air for: (2)
A
- ECS (ground operations only)
- Holds the “Aft Safety Valve’ Open (ground operations only)
5
Q
APU FADEC
- The FADEC monitors critical/major faults and will command shutdown based on: (9)
A
- Overspeed
- Underspeed
- Start Failure
- Acceleration Failure
- EGT Overtemperature
- High Oil Temperature
- Low Oil pressure
- Failed Sensors
- Internal Failure