某飞机舵机在地面随机振动试验后其电传功能失效，分解发现其中的电门支架和传感器支架均已断裂。采用断口分析、化学成分分析、硬度测试和金相检验等手段对该舵机失效原因及首断件进行了分析。结果表明：电门支架为该失效舵机各断裂件中的首断件，电门支架断裂的主要原因是其断裂处在振动试验前就已存在裂纹；舵机失效过程为电门支架首先发生准解理断裂后，其中一块断口由于失去固定作用对传感器支架产生撞击，进而又引起传感器支架发生疲劳断裂。

The switch support stand and sensor support stand of the airplane control actuator fractured after random vibration test. The failure reason of the control actuator and the initial fragment were analyzed by means of frature analysis, chemical compositions analysis, hardness test and metallographic examination. The results show that the switch support stand was the initial fragment. Switch support stand fractured firstly by quasi-cleavage, and then the sensor support stand was impacted by the fracture of switch support stand and caused the fatigue fracture of the sensor support stand. The crack existed in the switch support stand before random vibration test was the main reason for the fracture of the switch support stand.