05 Auxiliary Power Unit

Question 1

• APU maximum operating altitude?
• At what altitude is it guaranteed to start?
• At what speed is it guaranteed to start?

Answer 1

• 20,000 ft MSL.
• Below 15,000 ft
• 141 to 290 KIAS

Question 2

In flight bleed air extraction is not permitted above?

Answer 2

14,500 feet.

Question 3

The APU generator adapter drives a?

Answer 3

30 kVA, 400 Hz, three-phase AC generator

Question 4

You have to wait a minimum of XX minutes after APU shutdown to check oil level?

Answer 4

30 minutes

Question 5

What is the normal fuel supply to the APU? And what is the backup?

Answer 5

Right main tank. Left engine fuel feed manifold in case of negative G conditions.

Question 6

What powers the APU fuel pump?

Answer 6

DC battery BUS

Question 7

In the event of an APU fire, and the negative-G shutoff valve fails to close, what must you do?

Answer 7

Shut down the left engine in order to shut off fuel supply to the burning APU

Question 8

The APU battery provides the cranking power to turn the APU starter, how much volt is required?

Answer 8

22 volts

Question 9

When is the APU ignition system energized and de-energized during start?

Answer 9

After the START/STOP is pressed and APU RPM reaches 10%. It is de-energized when RPM reaches 95%

Question 10

What happens when you press PWR FUEL?

Answer 10

APU fuel shutoff and negative-G shutoff valves opens, APU fuel pump energizes and the APU gauges is displayed on the EICAS

Question 11

When does the starter cutout during APU start?

Answer 11

60% RPM (APU100)
35-45% (APU150)

Question 12

When is APU available after start, and when does the APU GEN OFF caution light come on?

Answer 12

4 seconds after 95% RPM, and 15 seconds after reaching 100% RPM

Question 13

If time permits, allow the APU to stablize for how many minutes before applying bleed air loads?

Answer 13

2 minutes