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某飞行学院Cessna172R机群短时间内出现18起燃油导管固定螺帽裂纹故障,对机队飞行安全构成较大威胁。本文根据螺帽材质化学成分、使用环境及裂纹特征,确定了裂纹属于应力腐蚀裂纹(SCC)。同时基于试验验证结果,估算出在成都周边大气环境下,可能导致该型螺帽出现应力腐蚀致裂纹的临界力矩值范围,由此确定了拧紧力矩值和维护措施。研究成果成功消除了燃油导管螺帽裂纹故障,保证了飞行安全。
A flight college Cessna172R fleet within a short period of time 18 fuel conduit fixing nut crack failure, pose a greater threat to fleet flight safety. Based on the chemical composition of the nut material, the use of the environment and the characteristics of the crack, it is determined that the crack belongs to the stress corrosion cracking (SCC). At the same time, based on the test results, the range of critical moment which could lead to stress corrosion cracking of the nut was estimated under the atmospheric environment around Chengdu, and the tightening torque value and maintenance measures were determined. The research successfully eliminated the crack of the fuel conduit nut and ensured the flight safety.