G550 APU

Question 1

1. How many lights / items appear during an APU fire test?

Answer 1

Eight (8)

• 2 OVERHEAD / 4 MASTER CAUTION PANEL / 2 CAS

Question 2

The APU is guaranteed to start at or below:

Answer 2

• 39,000’ (may start up to 43,000’)

Question 3

What is the max operating altitude of the APU?

Answer 3

45,000’

Question 4

The APU generator will come on when it has reached:

Answer 4

99% after 2 seconds

Question 5

After APU start and selecting APU BLEED AIR, when does the Isolation Valve automatically open?

Answer 5

APU load control valve is inhibited OFF during APU start and 1 minute after APU is online unless EGT before start > 150º. There is no delay when airborne

Question 6

What is the difference between ESSENTIAL and NON ESSENTIAL APU mode?

Answer 6

ESSENTIAL – Air * NON ESSENTIAL – Ground(15 minutes after landing) * Not all AUTO shutdowns are active in ESSENTIAL mode

Question 7

If the APU is started in flight what mode is the APU in?

Answer 7

ESSENTIAL mode

Question 8

While flying at 41,000’ an emergency condition requires operation on main batteries only:

Answer 8

• If the APU is available for use, you should:
• Immediately descend to the APU start envelope altitude (39,000 feet or below)

Question 9

What are the APU starter limitations when using aircraft batteries?

Answer 9

• 3 (three) start attempts
• Then 1 (one) hour cool down period

Question 10

What are the APU starter limitations when using DC external power?

Answer 10

• 3 (three) start attempts
• A 15 (fifteen) minute cool down is required between start attempts to protect aircraft wiring.

This allows the electrical feeder cable from the external power receptacle to the APU starter to cool
* Then 1 (one) hour cool down