Our horizontal stabilizer trim actuators (HSTAs) maintain the most optimum horizontal stabilizer surface on the airplane, improving fuel efficiency and reducing pilot workload. With over 25 years of HSTA experience, Parker has strong heritage in electromechanical HSTAs for aerospace commercial applications. Our broad experience and HSTA pedigree includes business jet, regional jet, and transport markets.

Our HSTA designs meet the most stringent safety regulations driven by the certification authorities (FAA and EASA). In order to meet these safety requirements, the HSTA is designed as two actuators in one. The HSTA has two different load paths (ball screw and safety rod) connecting the stabilizer surface to the aircraft structure.

The ball screw is driven by two electric brushless DC motors via a torque sum gear train. The HSTA has primary-load-activated passive brake (skewed roller) and an electric fail-safe electromechanical brake. The position of the stabilizer surface is captured via two rotary variable differential transformers (RVDTs). In case of a primary load path failure, the primary load path is locked in place and the load is transferred to the secondary load path.

APPLICATIONS:
This product and technology is used to maintain the aircraft pitch attitude and stabilizer surface position on a variety of commercial airplanes such as business jets, regional jets, and commercial transports.

FEATURES AND ATTRIBUTES:
• High fault tolerance design with superior reliability
• Parker-designed skewed roller no-back brakes are proven in multiple HSTA applications, providing consistent friction coefficient, long life, and low wear
• Brushless motors with proven Parker design; compact integrated package using a highly-reliable resolver for commutation, reducing cost and weight
• Gearbox features a compact and robust design using optimized-modified gearing with specialized heat-treating processes that reduces weight and provides greater reliability
• Electronic primary-load-path-failure-detection with anti-backlash keys (upper and lower) provides immediate failure detection with controlled low backlash to meet flutter requirements
• Electronic motor-control unit provides digitization of HSTA sensor data, independent monitoring of electronics, and built-in test and system health monitoring
• Dual channel brake means each channel provides full functionality in a proven, light-weight design
• Dual channel position sensor units offers a RVDT design with robust ball screw interfaces, plus provides feedback for stabilizer surface