Propellers Flashcards
What is the function of a propeller?
The propeller blades create thrust to pull or push an airplane through the air
What is the difference between a fixed pitch propeller and a controllable pitch propeller?
A fixed pitch propeller is one that has a built in blade angle that cannot be changed by the pilot. A controllable pitch propeller is one that can be changed by the pilot and is usually controlled by a governed that maintains a constant speed. Some controllable propellers also provide reverse pitch and feathering
How are some wooden propeller blades protected from wear and damage?
By metal tipping fastened to the edge and tip
What happens to the blade angle of a constant speed propeller during a constant power dive?
The blade angle increases to prevent an over speed
What are the functions of a constant speed propeller governor?
It boosts engine oil pressure before it enters the propeller hub, it senses rotational speed of the propeller and then adjusts oil flow to the propeller hub to change pitch and therefore speed of the propeller
What is the purpose of a propeller counterweight?
Centrifugal force acting on the counterweights causes the blade angle to increase
What is meant when a propeller governor is in an on speed condition?
The governor is not accelerating or decelerating and the speed or spring and flyweight forces are in balance
How is a constant speed feathering propeller feathered?
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 in most turboprops or can be manually controlled by the pilot moving the propeller control into a feathering detent
What is an unfeathering accumulator?
It is an oil accumulator used to provide oil pressure to unfeather the propeller
What is an alpha range and a beta range and where are they found?
The alpha and beta ranges pertain to the operating modes of a turbo prop reversible pitch propeller. 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 or minimum thrust range and negative thrust or reverse thrust mode, which is usually on the ground
What systems are commonly used for propeller ice control?
Fluid or alcohol and electrical heat applied to the propeller blades root
What propeller repairs can be performed by a certified mechanic with a power plant rating?
Only minor repairs and alterations can be performed by a certified mechanic with a power plant rating. Major repairs can be performed by the manufacturer or certified repair station. The propeller manufacturer’s maintenance manual outlines the scope of the repairs
How are wooden propellers generally cleaned?
With a brush or cloth and warm water with mild soap
Where would you find the correct method and technique for cleaning an aluminum propeller and hub?
The propeller manufacturer’s maintenance instructions
What type of non-destructive testing should be accomplished to a propeller after blending?
The procedures recommended by the manufacturer
