What is the purpose of the pulley stop screw on a propeller governor?

• A. to adjust the maximum engine speed during takeoff
• B. to adjust the minimum idle speed
• C. to calibrate blade angle biases
• D. to adjust governor spring tension

Answer: (A)

The pulley stop screw sets the upper travel limit of the governor linkage, which directly caps how far the propeller pitch can move and thus the maximum RPM the engine will reach. In other words, during takeoff you want a controlled, safe top speed, and the stop screw fixes that limit by preventing the governor from driving the propeller to a higher pitch (and higher speed) than set.

Idle speed and blade-angle biases are controlled by other adjustments in the system, and governor spring tension affects how the system responds across speed ranges rather than setting that maximum limit.