Fracture fault analysis of tail rotor on a helicopter

Finding out the reason of the fracture fault of tail rotor on a helicopter is of practical significance for using and maintaining the helicopter and is of significant reference for improving safety of new type helicopter. The fracture fault of tail rotor blade on a helicopter is analyzed by fault tree analysis method, and the bottom event analysis results are obtained. Then, the macro and micro fractographic analysis of the tail rotor blade is carried out. Finally,the simulation analysis of the fractographic damage evolution of flexible beam is performed. The results show that the fracture property of the blade is low-stress and high-cycle bidirectional bending fatigue fracture. When the strength value of the fiber compression direction of the flexible beam is less than 700 MPa, the fractographic type is similar to that of the faulty tail rotor flexible beam. The tail rotor will produce large vibration under large fatigue load condition, and the increase of vibration can intensify the load of the tail rotor, which leads to the increase of load at the root of the flexible beam and exceeds the designed bearing capacity of the flexible beam, then fatigue fracture will occur at the root of the flexible beam of the blade.