某飞机舵机壳体在服役过程中多次发生漏油故障，采用化学成分分析、荧光渗透检测、断口分析、金相检验等方法对漏油壳体进行检测及分析，对不同批次壳体材料进行了力学性能测试。结果表明：在脉冲油压的作用下，舵机壳体传感器孔壁萌生裂纹，并进一步扩展导致漏油；故障批次壳体材料为再结晶等轴晶组织，正常批次壳体材料为枝晶网状晶界组织，组织差异导致材料力学性能的差异，故障批次壳体材料的横向力学性能、断裂韧度以及疲劳性能等均低于正常批次壳体材料；力学性能的降低是传感器孔薄壁部位产生疲劳裂纹的主要原因。

Oil leakage faults occurred many times in the service process of a aircraft steering gear shell. The oil leakage shell was detected and analyzed by means of chemical composition analysis, fluorescent penetrant testing, fracture analysis and metallographic examination. The mechanical properties of different batches of shell materials were tested. The results show that under the action of pulsed oil pressure, the sensor hole wall of the steering gear shell cracked and further expanded, resulting in oil leakage. The failure batch shell material was recrystallized equiaxed crystal structure, and the normal batch shell material was dendritic network grain boundary structure. The difference of microstructure led to the difference of mechanical properties of the material.The transverse mechanical property, fracture toughness and fatigue property of the failure batch shell material were lower than those of the normal batch shell material. The decrease of mechanical property was the main reason of fatigue crack in thin wall of sensor hole.