Spring tabs are used for the same purpose as hydraulic actuators-to aid the pilot in moving the primary control surface.ДЇigure 2-13 indicates how each trim tab is hinged to its parent primary control surface, but is operated by an independent control.

Spring tabs are similar in appearance to trim tabs, but serve an entirely different purpose. Thus, aerodynamic forces acting on the tab assist in moving the primary control surface. Only the servo tab moves in response to movement by the pilot of the primary flight controls.Д«alance tabs are designed to move in the opposite direction of the primary flight control. They aid in moving the main control surface and holding it in the desired position. Servo tabs, sometimes referred to as flight tabs, are used primarily on the large main control surfaces. Their purpose is to enable the pilot to trim out any unbalanced condition which may exist during flight, without exerting any pressure on the primary controls. Trim tabs can be used to correct any tendency of the aircraft to move toward an undesirable flight attitude. Trim tabs are small airfoils recessed into the trailing edges of the primary control surfaces. Included in the trim controls are the trim tabs, servo tabs, balance tabs, and spring tabs. Directional control is the left and right movement or yaw of an aircraft that is controlled by the rudder. Figure The flight control surfaces are hinged or movable airfoils designed to change the attitude of the aircraft by changing the airflow over the aircraftвЂ™s surface during flight. Longitudinal control is the climb and dive movement or pitch of an aircraft that is controlled by the elevator. Aircraft Primary Flight Controls The primary controls are the ailerons, elevator, and the rudder, which provide the aerodynamic force to make the aircraft follow a desired flight path.

Lateral control is the banking movement or roll of an aircraft that is controlled by the ailerons.

The rudder is normally operated by foot pedals on most aircraft. Typically, the ailerons and elevators are operated from the flight deck by means of a control stick, a wheel, and yoke assembly and on some of the newer design aircraft, a joystick. These surfaces are used for moving the aircraft about its three axes. The flight control surfaces are hinged or movable airfoils designed to change the attitude of the aircraft by changing the airflow over the aircraftвЂ™s surface during flight. The primary controls are the ailerons, elevator, and the rudder, which provide the aerodynamic force to make the aircraft follow a desired flightpath.

Primary flight control system