Concerning the operating mechanism of a controllable-pitch propeller, what statement is true?

Correct Answer: Option D — If the hydraulic actuator is inboard, a mechanical pull-push rod is located within the propeller shaft. If the hydraulic actuator is outboard, hydraulic oil pipes are located within the propeller shaft.

Inboard hydraulic actuators utilize a mechanical pull-push rod through the shaft to adjust pitch. Conversely, outboard actuators mount directly to the hub, using hydraulic oil pipes within the shaft to supply the mechanism. Both designs effectively translate hydraulic pressure into blade angle changes.