Propellers Flashcards
(28 cards)
What is the function of a propeller?
Create thrust to pull or push an airplane through the air
How are some wooden propeller blades protected from wear and damage?
Buy metal tipping fastened to the leading edge and tip
What is the difference between a fixed pitch propeller and controllable pitch propeller?
Fixed pitch propeller cannot be changed by the pilot ( blade angle changed by the manufacturer only)
Controllable pitch propeller can be changed by the pilot ( blade angle changed by a selector valve or governor). Some can be reverse pitch and/or feathering.
What are the functions of a constant speed propeller governor?
Boost engine oil pressure before it enters the propeller hub
Sense rotational speed of the propeller
Adjust oil flow to the propeller hub to change pitch, and therefore speed of the propeller
What happens to the Blade angle of a constant speed propeller during constant speed power drive?
The blade angle increases to prevent an over speed
What is an unfeathering accumulator?
An oil accumulator used to provide oil pressure to unfeather a propeller
What is meant when a propeller governor is an on speed condition?
It is not accelerating or decelerating, and the speeder spring and flyweight forces are in balance
How is a constant speed feathering propeller feathered?
When the pilot moves the propeller control into the feathering detent, oil pressure in the governor is released, and the counterweights and feathering spring move the propeller into the feather
What is the purpose of propeller blade counterweights?
Forces the blade to a high pitched angle
To what do the terms alpha range and beta range pertain?
Those are the operating modes of turboprop reversible pitch propellers
What is the ALPHA range of a turboprop?
Range where the propeller operates in the standard constant speed mode. This is generally the in-flight range.
What is the BETA range of a turboprop?
Range where the propeller operates in the minimum thrust range and the negative or reverse thrust range. This is generally on the ground only.
What two forces are balanced in a propeller governor in an on speed condition?
Speeder spring tension and flyweight centrifugal force
What happens to a constant speed feathering propeller when the propeller governor oil pressure drops to zero?
The propeller will feather
How do you determine the repairability of a damaged propeller blade?
By referencing the manufacturers maintenance manual
What systems are commonly used for propeller ice control?
Fluid (alcohol) and electrical heat applied to the propeller blade root
What propeller repairs can be performed by a certified mechanic with a power plant rating?
Minor repairs and alterations. Major repairs or alterations can only be made by a certified repair station or the propeller manufacturer.
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 propellers manufacturers maintenance manual
What type of non-destructive testing should be accomplished to a propeller after blending?
Whatever procedures are recommended by the manufacturer
What are the two criteria used by many manufacturers to determine the amount of bend damage that can be repaired by cold bending aluminum propellers?
The extent of the bend and it’s blade station location
How can file marks be removed from an aluminum propeller after repair?
Using very fine sandpaper
When performing a static balance on a tube weighted propeller what positions must the propeller be placed in when the measurements are taken?
Vertical and horizontal positions
What is a propeller protractor used for?
To measure the propeller blade angle
