Propeller

Question 1

What type of propellers are utilized on the aircraft?

Answer 1

2x Hartzell constant speed, full feathering, 2 bladed hydraulic, metal

Question 2

Describe how the prop governor works.

Answer 2

Prop governor, located at the rear of the engine, changes the blade angle by porting oil to/from the propellor hub depending on the position of the fly weights.

The prop lever sets RPM and tension on the speeder spring, which determines the amount of centrifugal force required for flyweights to be in “on speed” position.

On Speed (neutral) pilot valve closed
Over Speed (flyweights swing outwards) pilot valve opens to sump to decrease RPM by increasing blade pitch
Under Speed (flyweights swinging inwards) pilot valve opens to pump engine oil to prop hub, increasing RPM by decreasing blade angle

Question 3

While on the ground, and shutting down the engines, what keeps the propellers from going into a feathered position? What RPM does it engage at?

Answer 3

Anti-feather locking pin

800 RPM

Question 4

Describe how the unfeathering accumulator will assist the propeller from coming out of the feathered position?

Answer 4

Accumulator with a diaphragm separating charged Nitrogen from engine oil (300psi). Prop lever to feather closes valve, trapping pressurized oil until prop lever moved to high RPM setting. Valve opens, oil pushed out to hub to decrease blade angle. Wind starts windmilling the prop, “less” stress on cylinders and engine can be restarted.