APU

Question 0

What controls the APU

Answer 0

A dedicated FADEC unit

Question 1

What kind of electrical power does the APU supply

Answer 1

115V 40 kVa

Question 2

What provides fuel to the APU for the following scenarios:

DC power only
AC power without engines
AC power with engines

Answer 2

DC power: a DC fuel pump located in the right wing tank

AC power without engines: the AC fuel pump

AC power with engines running: ejector pump provides fuel from right wing tank. It is possible to get fuel from left through the cross feed valve.

Question 3

What is the primary purpose for the APU bleed air

Answer 3

Engine starting and ECS bleed source on the ground

Question 4

What is the highest altitude for AC power from APU

Answer 4

33,000 ft

Question 5

What is the highest altitude for engine start using APU bleed air

Answer 5

21,000 ft

Question 6

What is the highest altitude for APU bleed air for pressurization and air conditioning

Answer 6

15,000 ft

Question 7

Max altitude for APU start

Answer 7

30,000 ft

Question 8

When is electrical and pneumatic loading available after APU start

Answer 8

3 secs after 95%

Question 9

During APU start, when does FADEC initiate ignition

Answer 9

6%

Question 10

During APU start, when does FADEC introduce fuel

Answer 10

.5 sec after ignition starts

Question 11

Which battery energizes the electrical starter controller of the APU

Answer 11

2 battery

Question 12

After light off, when does FADEC command the starter to cutout

Answer 12

50%

Question 13

When will FADEC shut down the APU on the ground

Answer 13

• Overspeed
• under speed
• FADEC critical fault
• APU fire
• APU egt over temp
• APU high oil temp
• APU low oil press
• sensor fail

Question 14

When will FADEC shut down the APU in flight

Answer 14

• Overspeed
• underspeed
• FADEC critical fault