How is RPM controlled on a turboprop?

• A. The propeller assembly and its control maintain a constant RPM at flight idle.
• B. RPM is controlled only by adjusting fuel flow to the turbine.
• C. RPM is varied by changing the propeller pitch with no governor.
• D. RPM is fixed and cannot be controlled.

Answer: (A)

RPM in a turboprop is kept at a set value by the propeller governor, which constantly adjusts the blade pitch to balance the load on the propeller. The throttle controls fuel to the turbine and sets the overall power, but the actual speed of the propeller is managed by changes in blade angle driven by the governor. When load increases, the governor increases pitch to slow the prop; when load decreases, it reduces pitch to let the RPM rise. This keeping of a chosen propeller speed—often held constant even at flight idle—is why the propeller assembly and its control are responsible for maintaining a steady RPM, rather than relying on fuel flow alone or having no governor.