APU

Question 1

What is the rating of the APU?

Answer 1

40kVA, 115 V AC, 400Hz, 3 phase

Question 2

How is the APU controlled and monitored?

Answer 2

Through its own dedicated FADEC

Question 3

What fuel pump supplies the APU with fuel?

Answer 3

• when only dc power available = DC pump
• if engine is not running and AC power available = right AC fuel pump
• if engine is running = right ejector pump

Question 4

What are the primary uses of the APU bleed air?

Answer 4

ECS and engine starting

Question 5

What is the max APU start altitude?

Answer 5

30,000ft

Question 6

What is the max APU use altitude?

Answer 6

33,000ft

Question 7

What is the max APU electrical supply altitude?

Answer 7

33,000ft

Question 8

What is the max APU assist engine starting altitude?

Answer 8

21,000ft

Question 9

What is the max APU altitude for ECS and pressurisation?

Answer 9

15,000ft

Question 10

How long after the EICAS is energised is it recommended you should wait before starting the APU?

Answer 10

30 seconds

Question 11

When do the APU electrical and pneumatic loads become available?

Answer 11

3 seconds after APU rpm has reached 95%

Question 12

For what conditions does FADEC provide automatic APU shutdown for on the ground?

Answer 12

Overspeed
Underspeed
FADEC critical fault
APU fire
APU egt overtemp
APU high oil temp
APU low oil pressure
Sensor fail

Question 13

For what conditions does FADEC provide automatic APU shutdown for in flight?

Answer 13

Overspeed
Underspeed
FADEC critical fault