Which of the following is NOT a basic type of propeller?

• A. Variable pitch
• B. Fixed pitch
• C. Ground adjustable
• D. Constant-speed non-feathering

Answer: (A)

Understanding how propeller pitch is classified helps here. Propellers are grouped by how their blade angle is controlled. A fixed-pitch propeller has a single, unmoving blade angle. A controllable-pitch propeller can vary the blade angle to suit conditions. Within controllable-pitch, you’ll see designs that are adjusted on the ground (ground adjustable) and those that actively maintain engine speed in flight (constant-speed). Variable pitch describes the capability to vary the blade angle, but it isn’t itself listed as a separate basic type of propeller. It’s a characteristic of controllable-pitch designs, not a distinct category. So the option that names variable pitch isn’t a basic propeller type, making it the correct choice. The remaining options refer to actual basic forms: fixed-pitch is a basic type, ground-adjustable is a controllable-pitch variant, and constant-speed non-feathering describes a specific capability within the constant-speed family.