Auxiliary Power Unit

Question 1

The APU is equipped with a dedicated FADEC.

T or F

Answer 1

True

Question 2

When are electrical and pneumatic loading available during an APU start?

Answer 2

When the APU has reached 95% RPM plus 3 seconds.

Question 3

During the normal shutdown sequence, APU bleed air is immediately removed and electrical power is removed after a 1 minute cool down period, followed by a spool down period.
(T or F)

Answer 3

True

Question 4

In flight the APU automatically shuts down for:

Answer 4

1. Overspeed
2. Underspeed
3. FADEC critical fault

Question 5

What is the APU used for?

Answer 5

1. Electrical power

2. Bleed air

Question 6

What monitors and controls the APU?

Answer 6

It’s own dedicated FADEC

Question 7

How is Battery 2 used for APU start?

Answer 7

It powers the APU start bus.

Question 8

What is the fuel source for the APU?

Answer 8

Right Fuel Tank or Left Fuel Tank through the Crossfeed Valve

Question 9

What Fuel Pump is used for APU Start with Batteries ON only?

Answer 9

DC Fuel Pump

Question 10

What fuel pump is used for APU start with an AC powered aircraft?

Answer 10

AC Fuel Pump 2

Question 11

What fuel pump is used for APU start with only the Right Engine running?

Answer 11

Right Ejector Fuel Pump

Question 12

Will the APU shut down automatically if the APU fails to start within the normal start cycle time period?

Answer 12

Yes

Question 13

What does moving the APU Selector knob to OFF do?

Answer 13

Initiates a normal APU shutdown with a 1-minute cool down

Question 14

Can the APU pneumatics be used during the cool down period?

Answer 14

No

Question 15

Can the APU electrical power be used during the cool down period?

Answer 15

Yes

Question 16

If you need the APU 50 seconds into shutdown is there a way to stop the shutdown?

Answer 16

Yes, turn the APU Master knob to ON

Question 17

How can the APU be shutdown immediately?

Answer 17

Push in the guarded APU EMER STOP button

Question 18

What conditions will the APU automatically shutdown on the ground?

Answer 18

1. Overspeed
2. Underspeed
3. FADEC critical fault
4. APU fire
5. APU high oil temp
6. APU low oil pressure
7. APU EGT over-temp
8. Sensor fail

Question 19

When does the Red Bar on the APU EMER STOP button illuminate?

Answer 19

When an APU fire has been detected.

Question 20

What happens when the APU EMER STOP button is pushed in?

Answer 20

1. The APU fuel shutoff valve closes and;

2. The APU shuts down without a cool down period.

Question 21

During normal operations on the ground with the APU running, it is normal to see the fuel unbalanced with less fuel in which tank?

Answer 21

Right fuel tank

Question 22

What is the altitude limit for an APU start? [SOP Limitation]

Answer 22

30,000’

Question 23

The operational altitude limit for the APU is? [SOP Limitation]

Answer 23

33,000’

Question 24

What is the APU operational limit for bleed air? [SOP Limitation]

Answer 24

15,000’

Question 25

What is the APU operational limit to assist an engine start? [SOP Limitation]

Answer 25

21,000’