What is the function of a servo in flight control systems?

• A. To measure airspeed.
• B. To indicate altitude on the instrument panel.
• C. To display weather information.
• D. To provide aerodynamic assist by moving opposite to the primary control surface.

Answer: (D)

The function of a servo in flight control systems is to provide the actual actuation that positions a control surface. It uses an electrical or hydraulic signal to generate motion, moving the surface to the commanded deflection. This movement effectively adds the needed force to overcome aerodynamic loads and carry out the pilot’s or autopilot’s commands, so the surface deflects in the direction required to produce the desired flight response. In practice, the servo drives the surface against the air forces, which is why it’s described as providing aerodynamic assist by moving the surface to the correct position. It isn’t responsible for measuring airspeed, indicating altitude, or displaying weather information.