Propellers Flashcards

1
Q

How are the props driven

A

Via a reduction gearbox

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2
Q

Type of propeller

A

3 blade, constant speed, feathering

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3
Q

Direction of rotation as seen from the cockpit
Left prop
And right prop

A

Both clockwise

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4
Q

Which is the critical engine

A

Left

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5
Q

Blade construction

A

Wood composite with steel leading edge

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6
Q

What 3 things control pitch angle

A

FADEC>CSU>PCU

Full Authority Digital Engine Control controls Constant Speed Unit, which controls Pitch Control Unit

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7
Q

What things cause the props to fine

A

Oil pressure from the CSU

Centrifugal twisting moments of the blades

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8
Q

What things cause the props to coarsen

A

A spring in the propeller hub

Centrifugal twisting moments of the counterweights

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9
Q

What oil does the CSU use to control blade pitch

A

High pressure oil from the gearbox pump

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10
Q

How does the CSU control the amount of oil going to the PCU

A

An electrically operated governor valve in the CSU

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11
Q

How is oil pressure to the CSU maintained in negative g

A

A capillary tube

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12
Q

What is the oil in the accumulator charged with

A

Nitrogen gas

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13
Q

How is the accumulator shutoff valve closed

A

When ENG MAST is switched off

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14
Q

How is the prop feathered in flight

A

ENG MAST OFF stops flow of oil to the CSU, allowing springs and counterweights to coarsen the blades

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15
Q

How is the prop unfeathered in flight

A

ENG MAST ON opens accumulator shutoff valve, allowing pressurised oil to reach the CSU for it to fine the blades

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16
Q

What is the function of the accumulator

A

Ensure there is enough high pressure oil available to unfeather the blades, even if the engine isn’t running, and that a constant uninterrupted flow is provided to the CSU, even if gearbox pump flow reduces momentarily

17
Q

Below what RPM will the prop blades not feather

A

1300 rpm

18
Q

What stops the blades feathering below a certain RPM

A

A centrifugal latch holds them at the start lock position

19
Q

What angle are the blades at the feathered and stop lock positions

A

Approx 81 deg

Approx 15 deg