APU

Question 1

Us of the APU during flight is prohibited except for the following:

Answer 1

Dual engine failure during flight
Dual generator failure during flight
Single engine failure during flight
Single generator failure during flight
“Bleeds Off” takeoff, up to a maximum of 5000’ AGL

*Dispatch is not permitted with any engine generator inoperative.

Question 2

APU ground limitations?

Answer 2

Unattended ground operations of the APU are prohibited.

Question 3

APU limitations

Answer 3

35,000 BAAV (Bleed Air Augmentation Valve)
- 15 second delay in the start sequence above 35,000’
16,500 SCV (Surge Control Valve) — controlled by the ECU
Guaranteed to start up to FL390
May start up to FL430
Will operate up to FL450
Wait until 5% to shutdown the master so the APU is ready for the next start
>22v on the main batteries for APU start

Question 4

What is the non-essential mode for the APU?

Answer 4

A list of items that will cause the APU to shutdown while on the ground.

Question 5

Can the APU fight its own fire?

Answer 5

No.

Question 6

How would we shutdown the APU in flight with an APU Essential CAS message illuminated?

Answer 6

With the APU MASTER OFF switch.

This is due to the fact that a “false” overspeed signal (the normal shutdown procedure) may not shutdown the APU in flight.

Question 7

During engine start, when must IGN and SVO icons be extinguished?

Answer 7

IGN and SVO icons must be out by 47% HP.

Question 8

What kind of shutdown does the APU conduct?

Answer 8

A metered shutdown. Cannot turn off master until the RPM is <5%.

Question 9

Where can I find the procedure for an APU restricted airport?

Answer 9

QRH, alternate normals.

Question 10

When can we check APU oil levels?

Answer 10

Wait at least 15 minutes after shutdown (15-30 minutes).