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Trim Tabs

 Trim Tabs

  • Trim tabs are known as small airfoil movable vanes attached to the trailing edge of a control surface. These tabs are most commonly found on the primary flight controls on light aircraft which operator purely on mechanical basis.
  • however, you may find them on some commercial airplanes too such as on the Boeing 737 which are used as a mechanical backup to assist flight controls deflections in the event of power-assisted failure on the flight controls.
  • The function of a trim tab is basically to assist the flight crew to the operator the aircraft controls in terms of pitch, roll, or yaw with reduced input force required on the controls columns or rudder pedals reducing the pilot's Physical Load.
  • This tab operates through mechanical linkages that move in the opposite direction to the control surface direction. For example, when the pilot intends to pitch the aircraft nose up, the elevator tends to move upwards while the tab tends to move downwards.
  • The tab deflection creates aerodynamic boundaries which assist in the deflections of the elevator upward and this greatly reduces the pilots effort to pull the control columns even with air resistance acting over the surface.
  • Tabs are also used to correct any loses of stright level flights attitude during the cruise.

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