The Propeller Governor is a variable speed, variable control oil pump that adjusts the angle of the aircraft propeller blades. As the propeller blade angles are adjusted, the engine RPM increases or decreases based on the air resistance against the blades. The aircraft propeller governor works by modifying the pressure of the engine oil, which pushes against the blades, adjusting their angle. There are two types of Governor: those that increase the angle of the blades and those that reduce it.

Key components:
Solenoids
The Propeller Governor solenoid checks overspeed operation while the airplane is on the ground. The solenoids automatically feather the propeller. Pitch lock solenoids block the pitch of the propeller.
Accumulators
A release accumulator is a safety device that will release the propeller if the engine stops. This release allows the pilot to restart the engine.