12 Propellers

Question 1

1. What is the function of a propeller?

Answer 1

The prop blades create thrust to pull or push an airplane through the air.

Question 2

2. What is the difference between a fixed pitch prop and a controllable pitch prop?

Answer 2

Fixed is one that has a built in blade angle that can’t be changed by the pilot. Controllable is one that can be changed by the pilot controlled by a governor that maintains constant speed.

Question 3

3. How are some wooden prop blades protected from wear and damage?

Answer 3

By metal tipping fastened to the keading edge and tip.

Question 4

4. What happens to the blade angle of a constant speed prop during a constant power dive?

Answer 4

The blade angle increases to prevent an overspeed.

Question 5

5. What are the functions of a constant speed prop governor?

Answer 5

It boosts engine oil pressure before it enters the prop hub, it senses rotational speed of the prop, and then adjusts the oil flow to the prop hub to change pitch and speed of the prop.

Question 6

6. What is the purpose of prop counterweights?

Answer 6

Centrifugal force acting on the counterweights causes the blade angle to increase.

Question 7

7. What is meant when a prop governor is in an on speed condition?

Answer 7

The governor is not accelerating or decelerating and the speeder spring and flyweight forces are in balance.

Question 8

8. How is a constant speed feathering prop feathered?

Answer 8

By releasing oil pressure in the governor, the counterweights and feathering spring move the prop into feather. This happens automatically if the governor oil pressure drops to zero or can be manually controlled by the pilot by moving the prop control into the feathering detent.

Question 9

9. What is an unfeathering accumulator?

Answer 9

It is an oil accumulator used to provide oil pressure to unfeather a prop.

Question 10

10. What is alpha range and beta range and where are they found?

Answer 10

Alpha: prop is operating in standard constant speed mode usually in flight.
Beta: prop is operating in zero or min thrust and negative/reverse thrust usually on the ground.

Question 11

11. What systems are commonly used for prop ice control?

Answer 11

Fluid (alcohol) and electrical heat applied to the prop blade root.

Question 12

12. What prop repairs can be performed by a certified mechanic with a powerplant rating?

Answer 12

Only minor repairs and alterations.

Question 13

13. How are wooden props generally cleaned?

Answer 13

With a brush or cloth and warm water with mild soap.

Question 14

14. Where would you find the correct method and technique for cleaning an aluminum prop and hub?

Answer 14

The prop manufacturer’s maintenance instructions.

Question 15

15. What type of NDT should be accomplished to a prop after blending?

Answer 15

The procedures recommended by the manufacturer.

Question 16

16. What are the 2 criteria used by many manufacturers to determine the amount of bend damage that can be repaired by cold bending of aluminum props?

Answer 16

Extent of bend and its blade station location.

Question 17

17. How can repair file marks be removed from an aluminum prop?

Answer 17

Very fine sandpaper.

Question 18

18. When performing a static balance on a 2 bladed prop, what positions must the prop be placed in when measurements are taken?

Answer 18

Vertical and horizontal positions.

Question 19

19. What is a prop protractor used for?

Answer 19

To measure prop blade angle.

Question 20

20. What blade conditions can cause engine vibration?

Answer 20

A prop being out of track or balance, as well as incorrect blade angle setting.

Question 21

What is blade tracking?

Answer 21

Procedure that compares the position of the prop blade tips relative to each other.

Question 22

22. What controls both manifold pressure and RPM on an engine equipped with a fixed pitch prop?

Answer 22

Throttle.