APU Flashcards

1
Q

What services does the APU provide and what are they used for?

A

An electrical generator supplies 28 V DC to the electrical system. The pneumatic power is used for engine
starting and to supply bleed air to the air-conditioning pack of the environmental system (ECS). AOM 9-04-01

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2
Q

How is the APU controlled and monitored?

A

Through a dedicated Full Authority Digital Electronic Control unit (FADEC). AOM 9-04-01

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3
Q

What does pressing the APU ON/OFF button do?

A

It starts the ECU power-up sequence and initiates the APU built-in test (BIT). AOM 9-04-30

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4
Q

When does the START button on the APU CONTROL panel flash green?

A

During the ECU bit test. AOM 9-04-30

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5
Q

What does the START button on the APU control panel illuminating steady green indicate?

A

The APU is ready to start. AOM 9-04-30

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6
Q

If the START button on the APU control panel illuminates amber what does that indicate?

A

The APU start is inhibited. AOM 9-04-30

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7
Q

What are the APU starter limitations?

A

Up to three consecutive unsuccessful start attempts are allowed with 30 second intervals between
attempts. AOM 2-38

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8
Q

What MFD page can APU information be seen on?

A

The STATUS synoptic page. AOM 9-04-30

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9
Q

Which tank normally supplies fuel to the APU?

A

The right tank. AOM 9-04-50

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10
Q

Is it possible to feed the APU from the left wing tank? If so, how?

A

Yes, via the cross-feed system. AOM 9-04-50

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11
Q

Can the APU supply bleed air on the ground or in flight?

A

Yes. AOM 9-04-50

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12
Q

If the APU is the only source of electrical power on the ground, what buses can the APU power?

A

All of the airplane electrical loads and charge both batteries. AOM 9-04-30

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13
Q

If the APU is the only source of electrical power in flight, what buses can the APU power?

A

All electrical loads (except for the SHED BUSES) and also charging both batteries. AOM 9-04-50

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14
Q

What is the APU operating envelope for starting, operation and to supply electrical power?

A

Up to 31,000 feet. AOM 9-04-50 and AOM 2-38

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15
Q

Up to what altitude is the APU able to supply bleed air for engine starting?

A

Up to 23,000 feet. AOM 9-04-50 and AOM 2-38

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16
Q

Where does the APU get its power for starting?

A

The number two battery. AOM 9-04-50

17
Q

What should be displayed on the STATUS synoptic page if the APU oil quantity is sufficient?

A

A green “OK” AOM 3-01-10

18
Q

List the 4 conditions that will cause the APU to automatically shut down either in flight or on the ground.

A

Overspeed, under speed, ECU internal failure or an APU bleed leak. AOM 9-04-50

19
Q

List the conditions that will cause the APU to automatically shut down on the ground only.

A

APU fire, APU EGT over temperature, APU high oil temperature, APU low oil pressure, APU starter not disengaged or an APU fuel shut off valve failure. AOM 9-04-50