Which component contains mechanism for changing propeller blade angles?

• A. barrel
• B. dome
• C. spinner
• D. stationary section control assembly

Answer: (B)

The mechanism that changes propeller blade angles is housed in the dome. In a variable-pitch propeller, the pitch-change system sits inside the hub under the dome, where hydraulic pressure from the governor moves a piston and actuating linkage. This motion is transmitted to each blade to rotate it about its pitch axis, adjusting the blade angle uniformly.

The spinner is just a decorative/aerodynamic nose cone and does not contain pitch-changing parts. The barrel is a structural/hub component, not the site of the pitch mechanism. The stationary section control assembly provides the control linkage, but the actual actuation that changes blade pitch lives in the dome.