Extensive analysis of hardover and trim-runaway failures on TLUH mathematical model based on CS-29 requirements

Abstract

Flight control systems improve the handling qualities of helicopters based on their allowable control authority. However, in limited authority helicopters the control systems do not have high number of redundancy. Therefore, in the event of a flight control system failure a pilot must safely recover from the failure scenario. In such a case, the pilot should have enough time to react and recover back to the original flight condition. During the certifications process of a helicopter, failure scenarios should be demonstrated with piloted simulations and flight tests. Piloted tests consume too much time to analyze all the flight conditions that include control system failure. Therefore, desktop based simulation analyses can be conducted to determine the worst case regime and to obtain a statistical database related to control system failures. In this paper failure and actuator module that has been implemented is presented. Using implemented modules with an in-house development tool, actuator failure cases on TLUH based on Certification Specifications for Large Rotorcraft and Advisory Circular (CS/AC-29) are conducted. Results of the analyses are given in the final section. Results obtained from the piloted simulations conducted in system integration laboratory are compared with the results obtained from desktop based simulations.