Airborne fault injection system for airworthiness compliance of civil aircraft flight control systems

To address the contradiction between the necessity of fault simulation flight testing for airworthiness compliance of civil aircraft flight control systems and the safety risks caused by fault injection in flight, this paper proposes a flight test fault injection system capable of covering all flight control system failure modes to meet airworthiness verification requirements. The system has undergone extensive flight validation and supports airworthiness certification for a specific civil aircraft model. A data hub for flight test equipment, a fault injection control trigger program integrated into the flight control computer, and a simplified, multi-mode human-machine interface testing panel comprise the core of the fault injection system, which ensures the compatibility and authenticity of fault simulations. In addition, the system accomplishes dependable handling of abnormal operating situations through a variety of distinct fault excitation cutoff methods, amplitude limiting mechanisms, and monitoring protocols, thereby considerably improving safety and fault tolerance. Furthermore, a flight test simulation strategy targeting typical flight control system failures is presented. The feasibility of the proposed approach is ultimately verified through in-flight testing with onboard implementation.