1. PROPELLER

2. 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

3. Propeller Counter Rotating Constant Speed Controllable Pitch
Full Feathering
Hartzell

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

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

6. 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

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

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

9. Pitch Control
Low Pitch - High RPM
Oil Pressure
Aerodynamic

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

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

13. Feathering
Feathering Check
What if a prop feathers on shutdown?

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

15. Accumulator Oil Line

16. Accumulator

17. 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

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

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

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

21. end