某型支线飞机排漏阀安装时经常出现断裂的现象,针对这一典型安装断裂情况,该文通过宏观检验、断口分析和有限元计算对排漏阀断裂的原因进行了分析。结果表明:排漏阀断裂失效模式为外螺纹接头第一圈螺纹根部过载拉伸断裂,通过有限元计算得到了排漏阀螺母安装的定力值上限,避免排漏阀安装时再次发生拉伸断裂。 In the case of installation and disassembly of a type of regional aircraft, the phenomenon of breakage often occurs. In view of this typical installation and breakage situation, the paper analyzes the reason of the breakage of the drain valve by macroscopical inspection, fracture analysis and finite element analysis. The results show that the fracture failure mode of the drain valve is the overload tensile fracture of the root of the first turn of the male connector, and the upper limit of the fixed force value of the drain valve nut is obtained through the finite element calculation so as to avoid stretching again when the drain valve is installed fracture.