APU

Question 1

If more than 1000 lb of fuel have been loaded in the center tank and you need to run the apu, which fuel pump should you turn on so you dont get an imbalance prior to takeoff?

Answer 1

Left center

Question 2

If no fuel have been loaded in the center tank and you need to run the apu, which fuel pump should you turn on?

Answer 2

Left forward fuel pump

Question 3

Run the APU for how many minute before using it bleed air source?

Answer 3

2 minutes

Question 4

If APU MAINT Light is illuminated, what should you do?

Answer 4

If APU MAINT Light is illuminated, only operate the APU if

needed. Make AML entry.

Question 5

How many minutes should you wait after apu shutdown and apu gen bus off light extinguishes before turning the battery switch off?

Answer 5

2 or 3 minutes depending on aircraft

Question 6

What happens to the apu if you turn off the battery?

Answer 6

Apu shuts down

Question 7

What control module controls apu operation?

Answer 7

ECU - Electronic Control Unit

Question 8

Where does the apu get fuel from?

Answer 8

Left fuel manifold

Question 9

With no power on the airplane, how does fuel get to the apu for the initial start?

Answer 9

Suction feeds from the left fuel tank

Question 10

Does the apu have auto shutdown features?

Answer 10

Yes

Question 11

On the ground, what all does the apu auto shutdown for?

Answer 11

EGT exceedance
High oil temprature
Low oil pressure
Failure to start
Failure to accelerate
APU fire

Question 12

The APU door has how many positions?

Answer 12

3
Closed
Open ground
Open air

Question 13

What happens if you turn the battery switch off while the apu is running?

Answer 13

Apu shuts down

Question 14

Where do we get electrical power to start the apu if AC power is not available?

Answer 14

Airplane battery

Question 15

Where do we get electrical power to start the apu if AC power is available?

Answer 15

No 1 Transfer bus

Question 16

What powers the apu ECU?

Answer 16

Aircraft battery

Question 17

What is the load shedding priority for the apu if both air and electrics are being drawn from the apu?

Answer 17

Other than during engine starts, apu will unload bleed air demand

Question 18

On the ground, What is the load shedding priority for the apu if only electrics are being drawn from the apu and EGT or speed goes over acceptable limits or if there is an over draw of power?

Answer 18

Apu sheds some buses. Galley busses and main busses will be shed. You can reset them.

Question 19

Is there a DC fuel pump in the left fuel that helps the apu suction fuel on initial start if AC power is not available?

Answer 19

Its an option and unsure if AA has those installed on the aircraft

Question 20

How long is the apu automatic cooldown time once you place the switch to off?

Answer 20

1 minute

Question 21

Will the apu conduct the automatic 1 minute cooldown time if you shutdown the apu by pulling the apu fire handle?

Answer 21

No. Its an immediate shutdown.

Question 22

What manufacturer makes the Apu on the NG and Max?

Answer 22

Allied signal which became Honeywell

Question 23

Since the honeywell apu has a starter generator, it can be started with battery power or AC transfer bus 1 while the classics were battery start only. True or False?

Answer 23

True

Question 24

Is there an Apu Egt gauge on the max?

Answer 24

No. Its removed because the apu is highly automated using the FADEC on the APU.

Question 25

Can you continue to operate the APU if you see a maintenance light?

Answer 25

Yes. But you should put it in the logbook and let maintenance make a decision.

Question 26

Does the MAX have a blue apu maintenance light?

Answer 26

No. It is replaced by the door light.

Question 27

What will call the APU to auto shutdown?

Answer 27

Fire Low oil pressure Overspeed High oil temperature / Fault

Question 28

How does the apu shutdown when you place the switch to off?

Answer 28

It sends an overspeed signal to itself which causes it to shutdown.

Question 29

The apu can power both ac transfer buses both on the ground or in flight. True or false?

Answer 29

True

Question 30

Will switching the battery off weather in the ground or air cause the apu to shutdown?

Answer 30

Yes. The classics, it did not shut it down in the air.

Question 31

What is the primary source of power for starting the apu?

Answer 31

AC transfer bus 1. If its not available then the main battery is used. There is an auxiliary battery option available on the NG,s which can be used to start the apu.

Question 32

When does the ECU remove the start signal during an apu start?

Answer 32

At 70% speed

Question 33

The air that comes thru the apu air inlet is used for what purposes?

Answer 33

Provide combustion air as well as apu generator and oil cooling

Question 34

What is the purpose of the vortex generator in front of the apu air inlet?

Answer 34

Provides for better air flow into the inlet. There is also a flap that bends 25 degrees inward while the apu is running to better form airflow

Question 35

Is there an eductor air inlet on the max?

Answer 35

No. It is integrated into the apu door.

Question 36

What are the 3 apu door positions on the max?

Answer 36

Closed - 0 degrees Flight open - 17 degrees Ground open - 45 degrees

Question 37

Apu fire detection is by the battery bus or the hot battery bus?

Answer 37

Battery bus

Question 38

Apu fire protection is by the battery bus or the hot battery bus?

Answer 38

Hot battery bus

Question 39

Where is the apu fire bottle located?

Answer 39

The horizontal stabilizer assembly compartment in the tail of the a/c