When the control spring tension is increased, what is the effect on blade angle and RPM?

• A. RPM will decrease and blade angle increases
• B. RPM will stay the same
• C. blade angle will decrease and RPM will increase
• D. blade angle will increase and RPM will decrease

Answer: (C)

This question focuses on how the constant‑speed propeller governor responds to changes in the speeder (control) spring. The spring sets the speed point at which the propeller blade pitch starts to move toward a higher, coarser angle to control RPM.

If you increase the control spring tension, that set point moves to a higher RPM. In other words, the blades stay in a finer, smaller pitch for a longer range of RPM. With the blades more finely pitched, there’s less drag, so the engine can accelerate more before the governor pushes the pitch to a higher value. The result is blade angle decreases and RPM increases.