Abstract: The tail rotor is a vital component for balancing the main rotor counter torque and enabling directional control of the helicopter, and loss of tail rotor effectiveness (LTE) is one of the significant factors that threaten helicopter flight safety. Several flight accidents caused by LTE were combed and summarized, the definition of LTE and the aerodynamic mechanisms thereof were briefly introduced, and the specific causes of accidents were analyzed deeply from the aspects of environmental factors and flight personnel operation factors. The results reveal that LTE mainly occurs in the low-speed flight stage of helicopter and is susceptible to the influence of environmental wind. Finally, suggestions for the prevention of LTE and the coping strategies when LTE occurs are proposed.

Key words: helicopter; loss of tail-rotor effectiveness; flight accident analysis; vortex ring state

摘要： 尾桨是平衡旋翼反扭矩、控制直升机航向的重要部件，尾桨失效是威胁直升机飞行安全的重要影响因素之一。针对由直升机尾桨失效造成的若干起飞行事故进行了梳理与总结,简要介绍了尾桨失效的定义以及引发尾桨失效的空气动力学原理，并从环境影响和飞行人员操作因素方面深入地分析了事故发生的具体原因。结果表明：尾桨失效多发生于直升机低速飞行阶段，且易受环境风影响；最后针对预防直升机尾桨失效和发生尾桨失效时的处置措施提出了建议。

关键词: 直升机;尾桨失效;飞行事故分析;涡环状态