Definition
A control device, typically driven by engine oil pressure and flyweights, that automatically maintains a selected propeller speed (RPM) by varying the pitch of a constant-speed propeller's blades. As engine power or airspeed changes, the governor increases blade pitch to slow the propeller or decreases blade pitch to speed it up, holding RPM at the value set by the pilot's propeller control.
Plain English
A small mechanical brain that watches how fast the propeller is spinning and automatically twists the blades to keep that speed steady, even when engine power or airspeed changes.
Context Anchor
You encounter this term when learning about constant-speed propellers, propeller control, engine management, and complex-airplane operations.
Derivation
From Latin gubernare, 'to steer or control,' the same root that gave us 'govern.' A governor governs the propeller's speed — it keeps it within set limits rather than letting it run free.
Why Pilots Care
A working governor prevents propeller overspeeding that can damage the engine and ensures efficient operation across different flight conditions.
Analogy
Think of cruise control in a car. You set the speed you want, and the system automatically adjusts to hold it as the road goes uphill or downhill. The propeller governor does the same job for RPM.
Intuition Check
Do not think of governor as a person in government here. In this context, a governor is a mechanical control device that regulates speed.
Example Sentence 1
When the pilot pulled the propeller control back, the governor increased blade pitch to settle the engine at 2,300 RPM.
Example Sentence 2
During descent the governor fine-tuned the blade angle so RPM stayed constant even as airspeed increased.