Which of the following is NOT included in the rudder control system?

The rudder control system is an essential component for controlling the aircraft's yaw. In this system, centering springs, cables, and a bellcrank are all integral parts that contribute to the proper functioning of the rudder.

Centering springs help return the rudder to neutral when the pilot releases the controls, ensuring the aircraft maintains its intended flight path. Cables provide the physical connection between the pilot's controls and the rudder, transmitting forces that enable directional control. The bellcrank serves as a mechanical advantage, converting the push or pull from the cables into movement of the rudder.

In contrast, a bobweight is not a component of the rudder control system itself. Instead, it is typically used in the aileron system to enhance control responsiveness and stability, especially during maneuvers where adverse yaw is a consideration. Therefore, it does not belong in the context of the rudder control system, making it the correct choice for this question.