APU

Question 1

What is the APU automatically controlled by?

Answer 1

The Full Authority Digital Electronic Control (FADEC).

Question 2

Can the APU bleed be on with the engine bleeds selected?

Answer 2

No

Question 3

With the APU generator operating, which buses are powered?

Answer 3

All DC buses:

L/R MAIN BUSES
L/R ESSENTIAL BUSES
L/R SECONDARY BUSES

Question 4

What is the indication of an APU loop fault?

Answer 4

1. FAULT advisory light (amber) on the overhead APU fire panel.
2. CHECK FIRE DET warning light flashes

It means a fault or loss of signal in the APU fire Advanced Pneumatic Detector (APD)

Question 5

Will the APU operate in flight?

Answer 5

No

Question 6

How is the APU fire protection provided?

Answer 6

Fire protection is by a control amplifier and an Advance Pneumatic Detector (APD). The system monitors the APU hot section and exhaust whenever the Right essential 28 VDC bus is powered. It is operated from the fire protection panel (FPP) on the overhead console. The system has a stainless steel fire extinguisher bottle and distribution tubing, and an APD routed along the tailcone above the APU.

Question 7

What are the indications of an APU fire?

Answer 7

1. FIRE light (red)on the APU FPP, comes on
2. CHECK FIRE DET warning light flashes (red)
3. Master WARNING switchlight flashes (red)
4. APU FUEL VALVE CLOSED advisory light (white) on APU FPP
5. APU FUEL VALVE OPEN advisory light (out) on APU FPP
6. BTL ARM advisory light (amber); then (out) if the bottle has discharged (APU FPP)
7. EXTG switchlight (White) on APU control Panel.
8. FAIL segment (amber) (caution and Warning Panel)
9. APU caution light (amber)
10. Master CAUTION light flashes (amber)