Powerplant Systems & Components: Propellers 🔊 Flashcards
What is the purpose of a propeller?
To create thrust and either pull or push the airplane through the air
What are two types of propeller configurations?
Tractor type and pusher type
What type of propeller has the blade angle built into the propeller and cannot be changed?
Fixed pitch propeller
What is the purpose of the metal tipping on the leading edge of a wooden propeller?
To protect the propeller from FOD damage
What tool is used to determine propeller blade angle?
Universal propeller protractor
What are the aerodynamic forces and loads acting on a rotating propeller blade?
A rotating propeller is acted upon by centrifugal force, aerodynamic twisting, centrifugal twisting, torque bending, and thrust bending forces
What is the meaning of propeller blade “back” and “face”?
The curved side, facing away from the engine is the blade back. The flat side facing the engine and pilots is the blade face.
What should be used to clean aluminum and steel propeller blades and hubs?
A suitable cleaning solvent using a brush or cloth
What positions are used on a balance stand to check a two bladed propeller for static balance?
First the vertical position, then the horizontal position
Can a fixed pitch propeller’s pitch be changed?
No
Why do you put the blades of a counterweight propeller into high pitch before stopping the engine?
The propeller has a moveable cylinder that slides over a fixed piston. In the high pitch position, the cylinder moves inboard and covers the piston protecting it from exposed air, dirt, and moisture
Why are cones installed on splined shafts with a propeller?
The cones center the propeller on the shaft
How is feathering accomplished on a constant speed counterweight propeller?
By releasing the governor oil pressure on the counterweights. The feathering spring moves the blades to the feathered position and the oil returns to the engine.
What types of systems are used for deicing propellers?
Fluid or electrical deicing systems
What is the purpose of a slinger ring on some propeller installations?
Deicing fluid is ejected from a stationary nozzle on the engine into a u-shaped channel attached to the rear of the propeller assembly. The u-shaped channel is called the slinger ring.
What is blade tracking?
The process of determining the position of the tips of the propeller blades relative to each other
Do the counterweights on a constant speed propeller increase or decrease the blade angle?
The centrifugal forces of the counterweight increase the pitch of the blades
What should you adjust if a pilot requests 50 more RPM on an aircraft equipped with a constant speed propeller?
Adjust the governor’s prop-level set screw
What adjustments are powerplant mechanics allowed to make to the prop governor?
The maximum RPM stop
What are propellers indexed to the crankshaft for an engine?
To reduce vibrations
Can transverse cracks in a propeller be repaired?
No
What is the alpha range and beta range of a propeller?
Beta range is the condition of the propeller during ground operations and in the reverse pitch position. Alpha range is propeller position in flight.
When changing metal bushings on a wooden propeller assembly, a thorough inspection of the bolt holes should be accomplished. Why?
To check for elongation
What happens to a constant speed feathering propeller when the propeller governor’s oil pressure drop to 0 PSI?
It returns to the feathered position
What is the purpose of an arbor when balancing a propeller?
To support the propeller on the balance knives
What two forces are balanced in a propeller governor in an on-speed condition?
Speeder spring and flyweights
