APU

Question 1

When does the ‘APU RUNNING’ EICAS memo message display?

Answer 1

When the APU selector is ON and the APU N1 RPM is above 95% N1.

Question 2

Is electrical power available from the APU In-flight?

Answer 2

No

Question 3

Can the APU be operated In-flight?

Answer 3

Yes, only if started on the ground, it can be on up to 20,000’.

Question 4

How long should you wait before turning the battery switch to OFF after turning the APU off, and why?

Answer 4

At least 2 minutes, to ensure a full shutdown of the APU, with fire detection capability.

Question 5

What are the start sources for the APU, and what source do we normally use? (3 Items)

Answer 5

TR (Transformer Rectifier) when UTIL BUS 4 is powered,

APU Battery, when UTIL BUS 4 is not powered.

TR is the normal switch position.

Question 6

Is APU bleed air available in flight?

Answer 6

Yes, for 1 Pack, up to 15,000’.

Question 7

What APU components are powered by the APU Battery? (4 Items)

Answer 7

Inlet door,

APU Controller,

DC Fuel Pump, and

APU Fire Detection System.

Question 8

What APU components are powered by the Main Battery? (3 Items)

Answer 8

APU Fire Extinguisher,

APU Fuel Valve, and

Standby Power for the APU controller.