Jeppesen Chapter 12 - Propellers (22 items)

Question 1

Q1. What is the function of the propeller?

Answer 1

A1. The propeller blades create thrust to pull or push an airplane through the air.

Question 2

Q3. How are some wooden propeller blades protected from wear and damage?

Answer 2

A3. By metal tipping fastened to the leading edge and tip.

Question 3

Q4. What happens to the blade angle of a constant speed propeller during a constant power dive?

Answer 3

A4. The blade angle increases to prevent an overspeed.

Question 4

Q5. What are the functions of a constant speed propeller governor?

Answer 4

A5. It boosts engine oil pressure before it enters the propeller hub, it senses rotational speed of the propeller, and then adjusts the oil flow to the propeller hub to change the pitch and, therefore, speed of the propeller.

Question 5

Q6. What is the purpose of propeller counterweights?

Answer 5

A6. Centrifugal force acting on the counterweights causes the blade angle to increase.

Question 6

Q7. What is meant when a propeller governor is in an “on-speed” condition?

Answer 6

A7. The governor is not accelerating or decelerating and the speeder spring and flyweight forces are in balance.

Question 7

Q8. How is a constant speed feathering propeller feathered?

Answer 7

A8. By releasing oil pressure in the governor, the counterweights and feathering spring move the propeller into feather. This happens automatically if the governor oil pressure drops to zero (following an engine failure on most turboprops), or can be manually controlled by the pilot by moving the propeller control into the fathering detent.

Question 8

Q9. What is an unfeathering accumulator?

Answer 8

A9. It is an oil accumulator used to provide oil pressure to unfeather a propeller

Question 9

Q10. What is “alpha range” and “beta range” and where are they found?

Answer 9

A10. The alpha and beta ranges pertain to the operating modes of turboprop reversible-pitch propellers. In the alpha range, the propeller is operating in the standard, constant speed mode, which is usually in flight. In the beta range, the propeller is operating in the zero minimum thrust range and negative thrust or reverse thrust mode, which is usually on the ground.

Question 10

Q11. What systems are commonly used for propeller ice control?

Answer 10

A11. Fluid (alcohol) and electrical heat applied to the propeller blade root.

Question 11

Q12. What propeller repairs can be performed by a certified mechanic with a powerplant rating?

Answer 11

Only minor repairs and alterations can be performed by a certified mechanic with a powerplant rating. Major repairs must be performed by the manufacturer or a certified repair station. The propeller manufacturer’s maintenance manual outlines the scope of the repairs.

Question 12

Q13 How are wooden propellers generally cleaned?

Answer 12

A13. With a brush or cloth or warm water with mild soap.

Question 13

Q14. Where would you find the correct method and technique for cleaning an aluminum propeller and hub?

Answer 13

A14. The propeller manufacturer’s maintenance instructions.

Question 14

Q15. What type of nondestructive testing should be accomplished to a propeller after blending?

Answer 14

A15. The procedures recommended by the manufacturer.

Question 15

Q16. What are the two criteria used by many manufacturers to determine the amount of bend damage that can be repaired by cold bending of aluminum propellers?

Answer 15

A16. the extent of the bend and its blade station location.

Question 16

Q17. How can repair file marks be removed from an aluminum propeller?

Answer 16

A17. With very fine sandpaper

Question 17

Q18. When performing a static balance on a two bladed propeller, what positions must the propeller be placed in when measurements are taken?

Answer 17

A18. Vertical and horizontal positions.

Question 18

Q19. What is a propeller protractor used for?

Answer 18

A19. It is used to measure the propeller blade angle.

Question 19

Q20. What blade conditions can cause engine vibration?

Answer 19

A20. Vibration can be caused by a propeller being out-of-track and/or balance, as well as incorrect blade angle setting.

Question 20

Q21. What is blade tracking?

Answer 20

A21. Blade tracking is a procedure that compares the position of the propeller blade tips relative to each other.

Question 21

Q22. What controls both, manifold pressure, and r.p.m. on an engine equipped with a fixed pitch propeller?

Answer 21

A22. The throttle.

Question 22

Q2. What is the difference between a fixed pitch propeller and a controllable pitch propeller?

Answer 22

A2. A fixed pitch propeller is one that has a built-in handle angle that cannot be changed by the pilot. These propellers can have the blade angle changed by the manufacturer or an approved repair station to optimize performance. A controllable pitch propeller is one that can be changed by the pilot and is usually controlled by a governor that maintains a constant speed. Some controllable propellers also provide reverse pitch and feathering.