APU Flashcards

1
Q

When AC power is available, the fuel is supplied to the APU by which fuel pump?

A
  • Aft main pump 2
    and
  • Aft main pump 3 operating to prevent fuel transfer
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2
Q

On the -400, to what altitude is APU bleed air available in flight for one pack?

A

15,000

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3
Q

On the -400, rotating the APU selector to OFF begins the shutdown cycle by closing the APU bleed air valve. How long does the APU continue running unloaded for the cool down period?

A

60 seconds

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4
Q

For an APU battery start, prior to the start sequence, the APU battery powers which APU components?

A
  • APU starter,
  • inlet door,
  • controller,
  • DC fuel pump,
  • APU fire detection
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5
Q

If the APU is running, what occurs if the APU selector is rotated to the OFF position?

A

The APU continues running unloaded for a 60 second cool down period.

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6
Q

What does the EICAS memo message “APU RUNNING” indicate?

A

APU selector is ON and APU N1 RPM exceeds 95%

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7
Q

What condition is indicated by the EICAS advisory message APU?

A
  • Automatic shutdown of APU with APU selector ON;
    or
  • APU N1 RPM exceeds 95% with APU selector OFF.
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8
Q

During the APU battery start sequence, the APU battery powers which components?

A

APU starter only

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9
Q

APU selector to the OFF position resets auto shutdown fault logic except when the shutdown is due to what condition?

A

APU bleed duct leak

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10
Q

What is the maximum altitude the APU may be operated in flight?

A

20,000 ft

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11
Q

If the battery switch is positioned to OFF while the APU is running what would occur to the APU?

A

APU shuts down immediately

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12
Q

The APU:

A

If started on the ground can provide pneumatics for one pack up to 15,000’, operate unloaded to 20,000’, and cannot be started inflight

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13
Q

To maintain fire detections, how long after the APU selector is rotated to OFF should the crew wait until placing the battery switch OFF

A

2 minutes

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14
Q

APU bleed air is available in flight under what conditions?

A

One pack up to 15,000 ft

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15
Q

After moving the APU selector to OFF

A

Wait 2 minutes before turning the battery switch OFF to ensure fire detection

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16
Q

With AC electrical power available, moving the APU selector to ON:

A

Activates Aft boost pumps in Main Fuel Tanks 2 and 3

17
Q

The APU RUNNING memo message will appear on the Primary EICAS display when:

A

APU N1 RPM exceeds 95%

18
Q

The APU start source switch will normally be left in:

A

APU BATTERY

19
Q

When does the APU air inlet door open?

A

APU selector ON