A system for providing automatic trim control associated with a control surface
in an aircraft that utilizes at least two sensors that must agree in direction
before trim adjustment is made. Each sensor is provided with a separate an independent
controller channel to further enhance fail-safe operation. A trim sensor is placed
in the coupling link between a servo and aircraft primary control linkage leading
to the associated control surface. A trim sensor is provided that utilizes a spring
with a portion disposed laterally with respect to the direction of the force to
be measured. An arm is attached to the lateral portion of the spring to effect
motion that can be sensed by various sensors including optical, mechanical switch
and magnetic sensors.