PROPELLER

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

Propeller Counter Rotating Constant Speed Controllable Pitch Full Feathering Hartzell

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

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

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

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

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

Pitch Control Low Pitch - High RPM Oil Pressure Aerodynamic

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

Feathering Feathering Lock 950 RPM Spring loaded latches engage high pitch stop-plates Centrifugal Force Prevents Feathering During Shutdown 950 RPM

Feathering Feathering Check What if a prop feathers on shutdown?

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

Accumulator Oil Line

Accumulator

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

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

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

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

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