PROPELLER PROPELLER v DEFINITION A rotating airfoil with

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PROPELLER

PROPELLER

PROPELLER v DEFINITION – A rotating airfoil with 2 or more blades attached to

PROPELLER v DEFINITION – A rotating airfoil with 2 or more blades attached to (or integrated with) a hub v TWO BASIC CONFIGURATIONS – Tractor – Pusher v PURPOSE

Propeller Counter Rotating v Constant Speed v Controllable Pitch v Full Feathering v Hartzell

Propeller Counter Rotating v Constant Speed v Controllable Pitch v Full Feathering v Hartzell v

Propeller v Pitch Controlled By – – – Oil Pressure Aerodynamics Counter Weights Spring

Propeller v Pitch Controlled By – – – Oil Pressure Aerodynamics Counter Weights Spring Force Nitrogen Charge

Propeller v Nitrogen Charge – 33 to 41 PSI EXAMPLE: u 70 F=41 psi

Propeller v Nitrogen Charge – 33 to 41 PSI EXAMPLE: u 70 F=41 psi u 0 F=36 psi u

Propeller v Loss of Nitrogen Charge – Propeller Overspeed – Cannot Feather v “Safety

Propeller v Loss of Nitrogen Charge – Propeller Overspeed – Cannot Feather v “Safety feature inherent in this system” – loss of governor oil pressure u prop automatically goes to feather

Pitch Control v Hartzell Governor - Boosted Oil Pressure 275 psi Pressure relief 300

Pitch Control v Hartzell Governor - Boosted Oil Pressure 275 psi Pressure relief 300 to 325 psi

Pitch Control v High Pitch - Lower RPM – – Spring Force Nitrogen Charge

Pitch Control v High Pitch - Lower RPM – – Spring Force Nitrogen Charge Counter Weights Fully Feathered 79 to 81 degrees (Seminole)

Pitch Control v Low Pitch - High RPM – Oil Pressure – Aerodynamic

Pitch Control v Low Pitch - High RPM – Oil Pressure – Aerodynamic

Feathering Maximum Pitch v Reduce Drag v Increased Performance v Propeller Control v POH

Feathering Maximum Pitch v Reduce Drag v Increased Performance v Propeller Control v POH v – Feathering time 6 seconds – 10 to 17 Seconds with accumulator?

Feathering v Feathering Lock – Spring loaded latches engage high pitch stopplates – Centrifugal

Feathering v Feathering Lock – Spring loaded latches engage high pitch stopplates – Centrifugal Force – Prevents Feathering During Shutdown v 950 RPM

Feathering Check v What if a prop feathers on shutdown? v

Feathering Check v What if a prop feathers on shutdown? v

Unfeathering v Accumulator – Oil stored under high pressure – 90 - 100 PSI

Unfeathering v Accumulator – Oil stored under high pressure – 90 - 100 PSI – Nitrogen charged

Accumulator Oil Line

Accumulator Oil Line

Accumulator

Accumulator

Unfeathering With Accumulator Move prop control out of feather detent position v Stored oil

Unfeathering With Accumulator Move prop control out of feather detent position v Stored oil in accumulator is released back to prop governor and moves the prop to low pitch v Unfeathering 8 -12 seconds v Prop windmills v

Unfeathering Without Accumlator v Move prop control out of feather detent to high RPM

Unfeathering Without Accumlator v Move prop control out of feather detent to high RPM position v Use starter to start engine

QUIZ v What moves the propeller blades, on the Seminole, to the high pitch,

QUIZ v What moves the propeller blades, on the Seminole, to the high pitch, low RPM position? – 1. _______ – 2. _______ – 3. _______

Quiz v At what RPM will the feathering latch engage to prevent the propeller

Quiz v At what RPM will the feathering latch engage to prevent the propeller from going into the feather position during engine shutdown? v 950 RPM

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