Final answer:
An 'on-speed' condition for a propeller governor indicates that it is regulating the propeller speed to maintain the set RPM, ensuring efficient and consistent performance of the aircraft's engine.
Step-by-step explanation:
When a propeller governor is in an "on-speed" condition, it means the governor is functioning properly to maintain the propeller's speed at the set RPM (revolutions per minute) for a given power setting. In this condition, the propeller governor automatically adjusts the pitch of the propeller blades to increase or decrease drag and load, ensuring the engine operates within the desired performance parameters.
For example, if an aircraft's engine is running at a constant throttle, and the airflow changes due to altitude or speed variations, the governor will act to adjust the propeller blade angle to maintain consistent RPMs. This process helps the aircraft maintain optimal efficiency and performance. Governors are complex systems that involve hydraulics, flyweights, and pilot valves to perform this regulation.