APU

Question 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 > 150 degrees. 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

If started in the air, the APU will remain in ESSENTIAL mode for how long after landing?

Answer 8

Stays in ESSENTIAL mode 15 minutes after landing

Question 9

APU ESSENTIAL and NON ESSENTIAL modes depend on which system?

Answer 9

WOW - Weight on Wheels

Question 10

What does APU ESSENTIAL CAS mean?

Answer 10

• APU is operating in ESSENTIAL mode
• A NON ESSENTIAL shutdown signal is sensed
• The APU will continue operating

Question 11

If the APU is operating in essential mode while the aircraft is airborne, the APU will:

Answer 11

Continue to operate in Essential mode for 15 minutes after landing

Question 12

What CAS message should not be displayed after the APU Fire Test?

Answer 12

Fire Bottle Discharged

Question 13

The APU Surge Control Valve operates at what altitude and above?

Answer 13

16,500’ and above to prevent high altitude compressor stall

Question 14

The APU Bleed Air Augmentation Valve (BAAV) operates at what altitude?

Answer 14

35,000’ and higher - Allows 400 degree (Fahrenheit) air into the APU intake for APU starting

Question 15

The APU Bleed Air Augmentation Valve (BAAV) delays the APU start:

Answer 15

For 15 seconds to allow the APU to warm before starting at altitude.

Question 16

What temperature range is the APU oil tank heated?

Answer 16

+21C to +43C regardless of whether the APU is in use

Question 17

Depressing the APU STOP switch causes the APU:

Answer 17

Shutdown by simulating an overspeed

Question 18

How do you perform an immediate APU shutdown?

Answer 18

Push Master Switch

Question 19

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

Answer 19

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

Question 20

What are the APU starter limitations when using aircraft batteries?

Answer 20

• 3 (three) start attempts

- Then 1 (one) hour cool down period

Question 21

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

Answer 21

• 3 (three start attempts)
• A 15 (fifteen) minute cool down period 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 download