The document describes how a propeller governor system regulates propeller speed during flight. It works by using fly weights, levers, springs and a valve to control high-pressure oil flow to the propeller hub. During over-speed conditions, accelerating rotation pulls the fly weights outwards, reducing spring pressure and opening the valve to allow oil to the hub. This increases propeller pitch and slows rotation. During under-speed conditions, the opposite occurs - decelerating rotation pushes the fly weights inwards, increasing spring pressure and releasing oil from the hub to decrease pitch and speed up rotation.

2. Over-speed: Level to Descending (or unscrewing prop knob)
1. Accelerating rotation
pulls fly weights outwards

3. Over-speed: Level to Descending (or unscrewing prop knob)
1. Accelerating rotation
pulls fly weights outwards
2. Levers attached to fly weights
reduce spring pressure

4. Over-speed: Level to Descending (or unscrewing prop knob)
1. Accelerating rotation
pulls fly weights outwards
2. Levers attached to fly weights
reduce spring pressure
3. Valve opens allowing high-
pressure oil to prop hub.

5. Over-speed: Level to Descending (or unscrewing prop knob)
4. High pressure oil presses
the piston that forces
increased pitch which
slows rotation.
1. Accelerating rotation
pulls fly weights outwards
2. Levers attached to fly weights
reduce spring pressure
3. Valve opens allowing high-
pressure oil to prop hub.

6. Over-speed: Level to Descending (or unscrewing prop knob)
4. High pressure oil presses
the piston that forces
increased pitch which
slows rotation.
1. Accelerating rotation
pulls fly weights outwards
2. Levers attached to fly weights
reduce spring pressure
3. Valve opens allowing high-
pressure oil to prop hub.
5. Slowing rotation makes
fly weights close the valve.

7. Under-speed: Level to Climbing (or screwing-in the prop knob)
1. Decelerating rotation
moves fly weights inwards

8. Under-speed: Level to Climbing (or screwing-in the prop knob)
1. Decelerating rotation
moves fly weights inwards
2. Levers attached to fly weights
increase spring pressure on valve

9. Under-speed: Level to Climbing (or screwing-in the prop knob)
1. Decelerating rotation
moves fly weights inwards
2. Levers attached to fly weights
increase spring pressure on valve3. Valve opens allowing high-
pressure oil to be released
from hub to sump.

10. Under-speed: Level to Climbing (or screwing-in the prop knob)
4. Less pressure on the
piston allows prop to
decrease pitch which
speeds-up rotation.
1. Decelerating rotation
moves fly weights inwards
2. Levers attached to fly weights
increase spring pressure on valve3. Valve opens allowing high-
pressure oil to be released
from hub to sump.

11. Under-speed: Level to Climbing (or screwing-in the prop knob)
4. Less pressure on the
piston allows prop to
decrease pitch which
speeds-up rotation.
1. Decelerating rotation
moves fly weights inwards
2. Levers attached to fly weights
increase spring pressure on valve3. Valve opens allowing high-
pressure oil to be released
from hub to sump.
5. Speeding-up rotation
makes fly weights equalize
and close the valve.