APU

Question 1

What services does the APU provide and what are they used

Answer 1

An electrical generator supplies 28 V DC to the electrical system. The pneumatic power is used for the engine starting and to supply bleed air to the air-condition pack of the environmental system (ECS).

AOM 9-04-01

Question 2

How is the APU controlled and monitored

Answer 2

Through its own FADEC

AOM 9-4-1

Question 3

What does pressing the APU ON/OFF button do?

Answer 3

It starts the ECU power-up sequence and initiates the APU built in test (BIT)

AOM 9-04-30

Question 4

When does the START button on the APU CONTROL panel flash green?

Answer 4

During the ECU bit test

9-04-30

Question 5

What does the START button on the APU control panel illuminating steady green indicate?

Answer 5

The APU is ready to start

AOM 9-4-30

Question 6

If the START button on the APU control panel illuminates AMBER what does that indicate?

Answer 6

The APU start is inhibited

AOM 09-04-30

Question 7

What are the APU starter limitations

Answer 7

Up to 3 consecutive unsuccessful start attempts are allowed with 30 second intervals between attempts

AOM 2-38

Question 8

What MFD page can the APU information be seen on?

Answer 8

The Status SYNOPTIC page

AOM 9-4-30

Question 9

Which tank normally supplies the APU

Answer 9

Right tank

AOM 9-4-50

Question 10

Is it possible to feed the APU from the left tank? if so how

Answer 10

Yes, via the cross feed system

AOM 9-4-50

Question 11

If the APU is the only source of electrical power on the ground, what buses can the APU power?

Answer 11

All of them and charge the batteries

AOM 9-4-50

Question 12

If the APU is the only source of electrical power in the air, what buses can it power

Answer 12

All except for the shed buses, and also can charge the batteries

AOM 9-4-50

Question 13

Where does the APU get its power for starting?

Answer 13

Number 2 battery

AOM 9-4-50

Question 14

What should be displayed on the STATUS synoptic page if the APU oil quantity is sufficient

Answer 14

A green “OK”

Question 15

List the 4 conditions that will cause the APU to automatically shut down either in flight or on the ground

Answer 15

Overspeed,
under-speed,
ECU internal failure or an
APU bleed leak

Question 16

List the conditions that will cause the APU to automatically shut down on the ground only.

Answer 16

APU fire
APU EGT over temp
APU high oil temp 
APU low oil pressure 
APU starter not engaged 
APU fuel shutoff valve failure 

AOM 9-4-50