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Flashcards in APU Deck (12):

What does the APU supply?

28v DC power to main feeder bus.

Bleed air to ECS


What is the APU fuel consumption?

200 lbs/ hour


What are the APU restrictions?

Ground use only

Can't start during fueling operations

Can't be operated during gravity fueling

Gen on first before bleed air

Must not be operated unattended with passengers on board


What happens if you forget the APU on for takeoff?

Shuts off automatically on liftoff.


Can the APU bleed air be on with engine bleeds selected on?

What about a ground air cart?

No - desensitized by WOW



Where does the APU get it's fuel supply from?

Left tank


How long should you wait after starting the APU before you turn on the bleed air?

3-5 minutes


What are the APU temperature limits?

....with inlet louveres?

-54°C to 50°C or ISA +35°C

21°C with inlet louvers installed.


APU starting limits

1 minute on, 5 minutes off
1 minute on, 30 minutes off and maintenance action required.


What is a nice trick to increase success rate in starting the APU in winter?

Press the self test then wait 3-5 minutes before pressing the start button.


What precaution must be taken when using external power to ensure that the APU GEN comes on line in the event of GPU failure?

APU GEN needs to be reset or else it doesn't automatically kick in once GPU is offline. Therefore just cycle the APU GEN off then on after start up.


If pressing the APU PWR button does not shut down the APU, what can be done to shut down the APU?

Press the FIRE TEST button on the Fire Protection Panel (APU section is on the left part of FPP).