Trim tab

Trim tabs are small, movable surfaces located at the trailing edge of a control surface that relieve the control pressures required to maintain the desired flight path. They’re what allow pilots to fly “hands off” instead of fighting to maintain attitude in various pitch and power combinations, and they spare the leg workout of continuous rudder input to maintain coordination in steady flight. Imagine you’re flying straight and level and add power. The nose will rise and the airplane will start to climb unless you push the nose down with forward yoke or stick. Roll in the right amount of nose-down trim, however, and the elevator will stay just where you need it—no muscle required.

When you apply nose-down trim, the elevator trim tab rises. The airflow hits the raised trim tab, which forces the whole elevator downward. That downward-deflected elevator raises the tail, rotating the airplane around the lateral axis and lowering the nose. For nose up trim, the tab moves down, the elevator moves up, the tail moves down, and the nose rises.

Most commonly found on elevators, trim tabs also may be located on the rudder or ailerons. Some are ground-adjustable, while others may be adjusted in flight using a manual trim wheel, electric switch, or crank. A little trim goes a long way, so don’t try to control an airplane’s pitch using elevator trim. Establish your pitch attitude first and use trim to take the load off.

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