APU

Question 1

When does the PUMP FAIL light illuminate?

Answer 1

When the XFLOW/APU pump has failed. If this happens or under negative G loads fuel is supplied from the right engine high pressure fuel line.

Question 2

UWhen does the SOV FAIL light illuminate?

Answer 2

When the Fuel SOV has failed.

Question 3

What happens when the APU PWR FUEL switch light is pressed?

Answer 3

• APU ECU is armed for start
• APU air inlet is open ( APU Door opens)
• XFLOW/APU pump starts
• APU IN BITE test runs
• APU Gauges apear on ED2

Question 4

At what RPM does the ingnition start?

Starter Cut out?

Answer 4

10%

55%

Question 5

When will the APU automaticly shutdown?

Ground

Air

Answer 5

Ground: Fire, Overspeed (107% RPM), ECU failure, DC power loss, Loss of RPM or EGT, Slow start greater then 60 sec, Over Temp (EGT greater then 743 or 974 if RPM is less then 50%), High oil temp low oil presure, loss of intake door position, Overcurrent.

Flight: APU fire, RPM 107% or higher, ECU failure, DC power loss, loss of RPM signal, all others will allow the APU to run till on the ground then it will auto shut off after 60 sec when it reverts to ground mode.