APU

Question 1

Describe APU

Answer 1

Constant speed

Independent oil system

Single stage impeller w 2-stage axial-flow turbine

Has a dedicated FADEC

Question 2

Batteries for APU start?

Answer 2

Batt 2 powers APU starter

Batt 1 powers FADEC and EICAS for monitoring, fire protection and detection

Question 3

Fuel source for APU?

Answer 3

R tank

or

L tank via crossfeed valve

Question 4

Fuel pump for APU start?

Answer 4

Batt ON only: DC fuel pump in R tank

AC power: ACMP 2

R Engine on: Ejector fuel pump

Question 5

APU auto shutdown if speed and acceleration rate not reached in starting cycle time?

Answer 5

Yes

Question 6

Move APU switch to OFF does?

Answer 6

Initiate APU normal shutdown

1 min cooldown

No pneumatics (electrics are available during 1 min cooldown)

Question 7

Can APU shutdown be cxld?

Answer 7

Yes, moving start switch to ON b4 1 min cooldown is over

Question 8

Auto APU shutdown on ground due to ?

Answer 8

Under speed
Over speed
FADEC critical fault
FIRE
Overheat
High oil temp
Low oil pressure
Sensor failure

Question 9

APU auto shutdown in flight due to?

Answer 9

Under speed
Overspeed
FADEC critical fault

Question 10

Can APU b started after critical fault ?

Answer 10

No