Propeller Systems (Variable Pitch)

Question 1

What are the definitions of the following terms?
Coarse Pitch
Fine Pitch
Feather Pitch
Revering Pitch

Answer 1

Question 2

How is pitch changed in a variable speed prop?

Answer 2

Via a hydraulic system using engine oil controlled by the propeller governor to change the pitch of the blades

In a non-feathering system (single engines), the pitch is increased with increased oil pressure

In a full-feathering system (multi-engines), the pitch is decreased with increased oil pressure

Question 3

As you add oil to a full-feathering system, what happens to the pitch of the blades?

Answer 3

The pitch is decreased/becomes more fine

Question 4

As you add oil into a non-feathering system, what happened to the pitch of the blades?

Answer 4

The pitch increases/becomes more coarse

Question 5

What kind of pitch would moving the lever full-forward give?

Answer 5

Fine = Low angle of incidence = low/small angle of attack

Question 6

What do you use in aircraft with a variable prop instead of RPM?

Answer 6

Manifold Pressure

Question 7

If the outside air pressure is 29.92, what will the Manifold Pressure guage read at full throttle?

Answer 7

Just below 30”. The MP guage should be reading close to whatever the pressure it. There is a little bit of loss but should be close.

Question 8

If the throttle is pulled to idle, what will the MP guage read regardless of the outside air pressure?

Answer 8

Super low, around 10”

Question 9

When there is a MP guage, what do it and the RPM guage mean now?

Answer 9

MP: The power I have availible
RPM: How efficiently I am using that power with the pitch of my prop

Question 10

What is the perfect angle of attack for a prop blade?

Answer 10

2 to four degrees

Question 11

While within the governing range, if there are any changes in engine power and/or airspeed, the governer will…

Answer 11

Maintain a steady RPM if a constant-speed propeller system is used

Question 12

What drives the propeller blades of a full-feathering system towards coarse pitch?

Answer 12

Counterweights and internal springs

Question 13

Oil pressure boosted by the governor has the purpose of moving the propeller towards…

Answer 13

coarse pitch in a single-engine aeroplane

Question 14

As the oil pressure drops on a constant-speed non-feathering system, the governor would make the propeller…

Answer 14

full fine

Question 15

What happens to a centrifugal counterweight and springs propeller system when the engine quits during flight?

Answer 15

Because the engine is still windmilling, the gear still drives the governor. The governor will still operate as usual and change the blade angle so as to keep the RPM setting.

So the blades move towards the selected propeller RPM by becoming more fine

Question 16

What drives the governor?

Answer 16

The engine

Question 17

After startup a twin-engine aeroplane’s oil pressure…

Answer 17

rises, moving the propeller into fine pitch

Question 18

During takeoff in a constant-speed aeroplane, the propeller blades initially move towards…

Answer 18

Full fine for maximum power (kayak analogy)

Question 19

Which aeroplane operation would move the propeller pitch towards the high pitch stop?

Answer 19

High speed descent

Question 20

During an engine failure in a twin-engine, what guage is best to shaw which engine has failed?

Answer 20

EGT, temperature will drop because no combustion = no heat