AM.II.C.S10

From the FAA library

• Aviation Maintenance Technician Handbook - Airframep. 2-11
  Chapter 2: Aerodynamics, Aircraft Assembly, & Rigging › Trim Controls

  Trim Controls Included in the trim controls are the trim tabs, servo tabs, balance tabs, and spring tabs. Trim tabs are small airfoils recessed into the trailing edges of the primary control surfaces. [Figure 2-12] Trim tabs ... tendency of the aircraft to move toward an undesirable flight attitude. 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. Servo tabs, sometimes…

• Pilot's Handbook of Aeronautical Knowledgep. 6-10
  Chapter 6: Flight Controls › Flight Control Systems › Trim Tabs

  this case, the air flowing under the horizontal tail surface hits the tab and forces the trailing edge of the elevator up, reducing the elevator’s AOA. This causes the tail of the aircraft to move down and the nose ... move up. In spite of the opposing directional movement of the trim tab and the elevator, control of trim is natural to a pilot. If the pilot needs to exert constant back pressure on a control column, the need…

• Pilot's Handbook of Aeronautical Knowledgep. 6-2
  Chapter 6: Flight Controls › Flight Control Systems › Primary Flight Controls

  Flight Control Systems Flight Controls Aircraft flight control systems consist of primary and secondary systems. The ailerons, elevator (or stabilator), and rudder constitute the primary control system and are required to control an aircraft safely during flight. Wing flaps, leading ... edge devices, spoilers, and trim systems constitute the secondary control system and improve the performance characteristics of the airplane or relieve the pilot of excessive control forces. Primary Flight Controls Aircraft control systems are carefully designed to provide adequate responsiveness…