Trim Control
Proper trim technique is an important and ofter overlooked basic flying skill. An imporperly trimmed aircraft requires constant flight control pressure which causes tension and fatigue, is distracts the pilot from visual scans, and contributes to erratic attitude control inputs.
What is it for?
Trim control surfaces are used to take away any constant flight control pressure inputs provided by the pilot. For example, elevator trim is typical in light GA aircraft and is used to remove the workload from the pilot. If the pilot wanted to pitch down, they could adjust the elevator trim instead of having to use forwards pressure on the pitch flight control. This allows the pilot to focus on other tasks, such as scanning for traffic and maintaining situational awareness.
How do I Use it?
Most large airplanes come equiped with rudder, elevator, and airleron trim while smaller GA aircraft are only equiped with elevator trim. When multiple trim axes are available, they should be applied in this order: Rudder first, then elevator, and lastly aileron trim. If airspeed is varying, continuous trimming of the rudder and aileron produces unnecessary workload and distraction. Attemps to trim the rudder at differentiating airspeeds is impractical because many propeller planes have built-in compensation for the effect of a propeller's left turning tendencies. The correct procedure in applying trim is as follows; when the pilot has established constant airspeed and pitch attitude, the pilot should hold the wings level with the aileron flight control pressure while rudder control pressure is trimmed out. Finally, aileron trim should then be adjusted to relieve any aileron flight control pressure.
A properly trimmed airplane demonstrates good piloting skills. Any control forces felt by the pilot should be a result of deliberate and coordinate flight control pressure inputs.
Common Error
A common trim control error is the tendency to overcontrol the airplane with trim adjustments. Attempting to fly the airplane using trim control is a common error among even experienced pilots. The airplane attitude must be established prior to trimming to prevent this error.