Auxiliary Power Unit

Question 1

APU AC generator rating

Answer 1

115 volts 40 KVA

Question 2

APU fuel supply (pump priority)

Answer 2

DC only - DC fuel pump in right wing
AC available, engine 2 not running - AC fuel pump
Engine 2 running - ejector fuel pump from right wing (or left wing via crossfeed)

Question 3

Which battery energizes the APU electronic starter controller

Answer 3

Batt 2

Question 4

APU ALTITUDE EXCEED caution

Answer 4

APU operation ceiling has been exceeded (for non-ETOPS airplanes, the airplane is flying at or above 33,500 ft with the APU running)

Question 5

APU SHUTTING DOWN status

Answer 5

a normal APU shutdown has been commanded via the APU selector knob

Question 6

What causes the APU to automatically shut down on the ground? In flight?

Answer 6

GROUND:
Overspeed
Underspeed
FADEC Critical Fault
APU fire (after 10 secs)
APU EGT over temperature
APU high oil temperature
APU low oil pressure
Sensor fail

IN-FLIGHT:
Overspeed
Underspeed
FADEC Critical Fault

Question 7

APU electrical AC power usable up to what altitude?

Answer 7

33,000 ft

Question 8

APU bleed air for engine start usable up to what altitude?

Answer 8

21,000 feet

Question 8

APU bleed air for air conditioning usable up to what altitude?

Answer 8

15,000 ft

Question 9

When is APU electrical and pneumatic power available for use

Answer 9

95% +3 seconds

Question 10

What happens when the APU selector knob is turned to OFF when APU is running?

Answer 10

A one minute cool-down starts. APU pneumatic power is removed immediately and electrics are removed at the end of the cool-down period (unless there is another AC power source available, where electrics are removed immediately).

Question 11

What happens when the APU EMER STOP button is pressed with the APU running?

Answer 11

The APU shuts down without the one minute cool-down period.