Simulation analysis of a pitch trim actuator

This paper describes the architecture and modeling of a pitch trim actuator servo drive system designed by Woodward Inc. for a typical midsize business jet aircraft. The PTA system provides secondary pitch control by adjusting a set of trim tabs located on the trailing edge of the elevator surface. Trim tab commands are issued by the trim wheel or the trim switches located on the control stick in the cockpit. Thrust compensation commands and flap position commands may also be sent by the flight computer directly to the PTA system for appropriate pitch corrections. The solution consists of a linear actuator and two electronic control units. Simulation results are presented that demonstrate the accuracy and dynamic performance of the speed control system.