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B300 Course > 61 Propellers > Flashcards

61 Propellers Flashcards

1
Q

Describe the HC-B4-MP-3 propellor on the aircraft.

A

All metal, four bladed propeller, hydraulically controlled by engine oil, reversible, constant speed and full feathering.

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2
Q

What component manages speed control and where is it located?

A

single acting engine driven governor located on top of the reduction gearbox.

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3
Q

What backup system is there for the primary governor?

A

Overspeed governor and power turbnine (N2) governor which is integral to the normal or primary governor.

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4
Q

How is the propeller feathered?

A

The feathering spring completes the feathering operation when centrifugal twisting moment is lost.

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5
Q

What is used to aid increasing pitch (decrease RPM)

A

Centrifugal counterweights on each blade in conjunction with feathering springs.

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6
Q

How does the auto-feather system work?

A

By dumping oil from the propeller governor when engine torque-meter pressure drops below 4.7 PSI at power settings above 87 - 89% N1

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7
Q

Maximum take off RPM?

A

1700 RPM

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8
Q

Explain the operation of the primary governor.

A

Single acting governor which moves the blades towards low pitch (high RPM) hydraulic stop and reverse positions by porting oil to the prop through the hollow centre.

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9
Q

How does the primary governor control N2 power turbine speed?

A

By varying propeller blade pitch.

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10
Q

What controls the pilot valve?

A

Rotating flyweights and the prop control lever.

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11
Q

How does the governor handle a underspeed condition?

A

speederspring force overcomes flyweight force lowering the pilot valve directing oil into the prop hub to decrease blade angle (Increase RPM)

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12
Q

Explain an overspeed condition.

A

Flyweights overcome the speeder spring opening the pilot valve allowing oil to drain from the prop. the feather springs and counterweights take over increasing blade angle (decreasing RPM)

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13
Q

What other means does the governor have to protect from overspeed?

A

A fuel control section designed to protect from overspeed.

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14
Q

How does the fuel section operate to protect overspeed?

A

A pneumatic orifice is opened by a yoked bell-crank operated of the flyweight to reduce metered fuel to the engine.

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15
Q

Where is the propeller overspeed governor located?

A

Left side of the reduction gear housing.

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16
Q

What speed does the overspeed governor govern at?

A

104% N2 Speed approx 1768 RPM

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17
Q

How do you test the overspeed governor?

A

By holding down the test switch which activates the solenoid on the OS governor setting the test to 1560 RPM

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18
Q

Explain how the ground idle stop system works.

A

By using a solenoid mounted to the reverse/pull cable which is designed to work on the ground to maintain blade angle at 2 in ground idle.

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19
Q

The ground idle solenoid is wired though which squat switch?

A

Right landing gear squat switch.

20
Q

If one or both of the ground idle solenoids receive power for more than 10 seconds what happens?

A

You receive a yellow PROP GRND SOL annunciator.

21
Q

What inhibits the PROP GND SOL annunciator during ground operations?

A

Left squat switch

22
Q

How do the throttle levers activate the ground idle stop system.

A

Lifting either throttle lever to the beta range.

23
Q

Where is the low pitch warning sensor located?

A

On the right side of each engine adjacent to the beta ring.

24
Q

What will trigger your white L PROP PITCH and R PROP PITCH annunciators of the low pitch warning system?

A

The aft flange of the beta ring travels aft past the centre of the sensor.

25
Q

What are the L or R PROP PITCH annunciators used for?

A

To alert the pilot of a blade angle more than 8 degree’s below the flight idle low pitch stop. these annunciators are on during normal ground ops.

25
Q

What are the L or R PROP PITCH annunciators used for?

A

To alert the pilot of a blade angle more than 8 degree’s below the flight idle low pitch stop. these annunciators are on during normal ground ops.

26
Q

At what speed does the blade angle’s automatically reset from ground idle low pitch stop to flight idle low pitch stop.

A

68% - 70% N1 Speed

27
Q

Where is the test switch for the ground idle solenoid located?

A

lower left outboard subpanel.

28
Q

How is the propeller reversing system connected?

A

Via a push pull cable from the beta cam box which controls your fuel control unit as well as the brush block that slides in the beta ring.

29
Q

What stages of flight is the auto-feather system intended for?

A

Take off and landing, it should be armed until the aircraft has gained enough altitude.

30
Q

How does the autofeather system work?

A

Immediately dumps oil from the propeller governor to feather the prop blades.

31
Q

At what torque-meter oil pressure will the autofeather system dump oil?

A

7 to 13% torque at power settings of 87% - 89% N1 or greater.

32
Q

How is the autofeather system controlled?

A

a four pole double throw switch, ARM - OFF - TEST.

33
Q

Describe the activation of the auto feather system?

A
  1. Throttle levers above 87-89%
  2. Power routed to high press switch
  3. Ground applied to low press switch
34
Q

Describe the process of the autofeather system in the event of a engine failure.

A
  1. Eng TQ drop off tripping high press switch (4.7 PSI).
  2. Oil press continues to drop activating low press switch providing a ground and opening the AF Dump valve. Dumping oil press of the governor on the engine out.
35
Q

How does the test function work for the autofeather system?

A

Power levers are bypassed and voltage and ground supplied to respective switches allowing the pilots to test the system without having to advance power to 87-89% N1.

36
Q

How does the synchrophasing system work?

A

The control box senses pulses generate by the magnetic pick ups mounted at identical locations of each engine. Targets mounted on the spinner bulkhead provide the pulse data.

37
Q

How does the prop synch control box monitor the propellers.

A

Senses the rate and phase of the pulses and tries to superimpose the waveforms by adjusting prop speed of each engine.

38
Q

How does the prop sync control box sync the propellers?

A

By influencing the flyweights and the pilot valve in the governor. it has the authority to adjust between 23 to 27 rpm.

39
Q

How is the synchrophaser system turned on and off?

A

Through a push switch PROP SYNCH -ON-OFF

40
Q

What is the range called that the props need to be within for the sync to work?

A

Capture Range. turn off prop sync, manually match props, turn on prop sync.

41
Q

Where does the RVS NOT READY light activation switches receive its power from?

A

The landing gear handle when in the DOWN position.

42
Q

What is the purpose of the RVS NOT READY annunciator switches.

A

To prevent incorrect governing and asymmetrical engine operation.

43
Q

What activates the RVS NOT READY annunciator.

A

By retarding the prop lever from the high rpm position.

44
Q

A

servo piston mounted on the front of the propeller spider hub

A

moves the propeller blades through links connected to the trailing edges.

B300 Course (37 decks)

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