A Method to Determine Maximum Flight Control Authority Through Hardover Failure Testing

In order to implement the advanced control response types needed to improve rotorcraft handling qualities in degraded visual environments, the control authority available to affect aircraft handling qualities must be maximized. However, for flight control systems that lack the redundancy to detect and react to failures, the maximum control authority must also be limited to ensure that a pilot can safely recover from the worst-case failure which results in a full-travel hardover of an electromechanical series actuator. In the event of such a failure, the pilot must have enough time to recognize, react to, and recover from the hardover without exceeding allowable aircraft failure transient limits. Recently, simulation and flight testing were conducted to determine the maximum flight control authority for the ARH-70A. Analysis of this hardover data used a methodology to normalize pilot response time for each test point, thus minimizing the effect of pilot technique on the results. Normalized pilot response time was then plotted against hardover size to determine the series actuator limits based on the selected design criteria. The data collection and analysis method used to determine the maximum control authority for the ARH-70A can also be applied to other flight control system development efforts facing similar constraints.