Which statement describes a controllable-pitch propeller (CPP)?

• A. A fixed-pitch propeller with no ability to change pitch
• B. A type of propeller with blades that can be rotated around their long axis to change their pitch
• C. A propeller that automatically feathers for engine out
• D. A propeller that maintains constant RPM regardless of load

Answer: (B)

A controllable-pitch propeller is defined by blades that can be rotated around their long axis to change their pitch. That ability to adjust blade angle lets you optimize thrust and efficiency for different flight conditions: higher pitch for more thrust at a given engine speed during takeoff or climb, lower pitch to reduce drag and improve cruise efficiency, and even feathering the blades to minimize drag if an engine fails.

This pitch adjustment is the key feature that sets CPP apart from fixed-pitch props, which have a single blade angle and can’t be changed in flight. The idea of automatic feathering is a capability some CPPs have, but the defining aspect is the blade rotation to alter pitch. The notion of maintaining constant RPM regardless of load describes the governor’s role in a constant-speed propeller system, not the basic function of changing pitch itself.