What is the function of elevator trim and how does it affect flight?

• A. Trim changes engine RPM
• B. Trim alters wing shape
• C. Trim increases control forces
• D. Trim reduces control pressures and helps maintain stable flight; adjust to maintain desired pitch without continuous control input

Answer: (D)

Elevator trim sets a specific pitching moment on the airplane so you can fly with less effort on the controls. By adjusting a trim tab or the horizontal stabilizer, it changes the tail’s angle of attack to produce a small nose-up or nose-down force. This balances the aircraft’s aerodynamic loads so the airplane tends to maintain the chosen pitch on its own, rather than you having to hold constant back-and-forth pressure on the yoke.

Because of that, you can hold a steady airspeed and flight attitude with much less continuous control input, reducing control pressures and fatigue. It’s a convenience that helps keep flight smooth and stable across changes in weight, CG, or power settings. It doesn’t change engine RPM or the shape of the wings; its purpose is to fine-tune the longitudinal balance so you can relax the controls while maintaining the desired pitch. If the airplane tends to drift, you’d re-trim to restore the intended attitude without fighting the controls.