PMU system & associated malfunctinos/emergencies Flashcards Preview

C4 GK > PMU system & associated malfunctinos/emergencies > Flashcards

Flashcards in PMU system & associated malfunctinos/emergencies Deck (24)
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1
Q

The PMU & PIU automatically control the propeller ________(pitch) & propeller ________ (Np)

A

blade angle; speed

2
Q

True/False: The PMU controls the propeller RPM by varying the propeller blade angle with oil pressure through the PIU

A

True

3
Q

With the PMU functioning, the mechanical overspeed governor modulates oil pressure to the propeller pitch change piston to limit Np below _____, while the electronic governor will maintain Np at ¬¬¬______.

A

106%; 100%

4
Q

If PMU function is lost/deactivated, the mechanical flyweight overspeed governor modulates oil pressure to the propeller pitch change piston to maintain Np at or below___.

A

100±2%

5
Q

Feathering the prop…when the engine is shutdown, the PMU sends a signal to the ________valve to drain propeller oil pressure.

A

prop servo valve

6
Q

If the rate of change of propeller RPM occurs and exceeds the PMU sensor validity check limit, what will happen?

A

It will switch to manual mode

7
Q

Does the PMU energize & de-energize the igniters when the ignition switch is positioned accordingly?

A

Yes

8
Q

The PMU converts the 32 VAC from the PMA to ______.

A

DC

9
Q

True/False: The PMU automatically switches to the 28 VDC battery bus when propeller RPM drops below 40-50% Np, or when the PMA fails.

A

True

10
Q

PMU ground mode vs. flight mode

A

ground= 60-61%; Flight=67% (minimum)

11
Q

Above ______, the PMU raises N1 to maintain Np above 80% to avoid stress on the propeller during spins.

A

10,000’ft PA

12
Q

The PMU will auto abort an impending hot/hung start if ITT exceeds 940°C for _____, 870°C for _____, or 840°C for ______.

A

2 seconds, 4 seconds, 19 seconds

13
Q

True/False: The PMU automatic shutdown feature is enabled for airstarts.

A

False, the auto feature is disabled

14
Q

For engine starts, the PMU receives inputs from the ______ sensor located in the engine inlet plenum.

A

IOAT

15
Q

If IOAT is greater than 96°C, but less than 121°C, the PMU will default to ______°C for all PMU functions

A

121°C

16
Q

A dedicated ___________, mounted on the reduction gearbox, powers the PMU

A

Permanent magnet alternator (PMA)

17
Q

If the IOAT exceeds 121°C, what happens to the PMU?

A

It goes offline & will not reset until below 121°C

18
Q

If the ST READY light extinguishes during engine start, does the PMU auto abort function still work?

A

No, the start must be manually aborted

19
Q

Illumination of both PMU ____ & PMU ______ annunciators indicates the system is in manual mode.

A

FAIL, STATUS

20
Q

Why would the PMU STATUS light illuminate 1 minute after landing?

A

There were fault conditions not serious enough in-flight

21
Q

Why would the PMU STATUS light illuminate during flight?

A

Mismatch between the weight on wheels switch & notifies pilot the PMU will not revert to ground mode upon landing

22
Q

With the PMU off, the _______ will not automatically activate & must be selected manually for a PMU OFF AIRSTART.

A

Igniters

23
Q

True/False: PMU FAILURE-before resetting PMU or switching to OFF, set power at lowest practical to minimize power shift.

A

True

24
Q

Can you reset a PMU STATUS light in-flight?

A

No, the PMU detected a discrepancy w/the weight on wheels switch