NATOPS APU Flashcards

1
Q

What types of APUs do we have?

A

Turbomach/Sundstrand APU

Garret APU

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2
Q

What does the APU do?

A

It provides pneumatic power for starting the engines and operating the Environmental Control System (ECS)

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3
Q

What does the APU consist of?

A

It is a gas turbine engine with a power section, a reduction gearbox, appropriate controls, and accessories.

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4
Q

Fuel consumption at rated power is ___.

A

150 lbs per hour

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5
Q

Operations of the APU in flight (should/shall) be limited to ___.

A

Shall

essential operations only

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6
Q

What are the acceptable in-flight uses of the APU?

A
  • EPs
  • Single-engine training
  • practice autorotations
  • powering the ECS during extreme temperature operations
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7
Q

What are the APU system accessories?

A
  • prime/boost pump
  • hydraulic accumulator (with hand pump)
  • hydraulic starter
  • ac generator
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8
Q

What does the prime boost pump do?

A

Used to prime the engine or APU fuel lines.

Also provides fuel under pressure to the APU during starting and operations at pressure altitudes above 8000 ft

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9
Q

What does the hydraulic accumulator do?

A

provides the hydraulic pressure for driving the APU starter

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10
Q

What is the minimum accumulator pressure required for starting the APU?

A

2650 psi

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11
Q

With AC power available, the accumulator is charged by the ____.

A

backup hydraulic pump

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12
Q

What is the APU controlled and monitored by?

A

Electronic Sequence Unit (ESU) or Digital Electronic Sequence Unit (DESU)

Will automatically shut down the APU if a start sequence fails or a monitored parameter is exceeded during operation (exception of APU OIL TEMP HI)

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13
Q

The DESU for the Turbomach/Sundstrand APU has the added capability to control what?

A

APU overtemperatures by regulating the main fuel valve and start bypass valve

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14
Q

What does APU FAIL mean?

A

APU has failed due to:

  • High/Low Ng
  • High/Low TGT
  • Low Oil Pressure
  • Start sequence failure
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15
Q

Where is fuel supplied from for the APU?

A

The right fuel cell by the prime/boost pump

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16
Q

When does the APU ACCUM LOW advisory appear?

A

when accumulator pressure drops below 2650 psi

17
Q

What happens when you place the APU GENERATOR switch to ON?

A

Makes electrical power available

18
Q

If APU does not start and the APU ACCUM LOW advisory light is not illuminated, how do you attempt a start?

What happens once you do this?

A

A start may be attempted by simultaneously moving the APU CONTR switch to ON and actuating the manual START/OVERRIDE lever located on the Accumulator Manifold.

APU accum pressure will be dumped to the starter to turn the compressor until the APU has reached a self-sustaining speed.

19
Q

If the backup pump is cycled ON then to the OFF or AUTO position, it will remain on for one cycle of __. (__ with winterization kit installed.)

A

90 seconds

180 seconds

20
Q

(From Ch. 3) What happens if you fill the Turbomach/Sundstrand APU to the full line?

A

It will cause the APU to overheat