飞机水平安定面后梁中段失效分析与改进措施

Failure Analysis and Measures on Cracking of Rear Beam of Horizontal Stabilizer of Aircraft

针对飞机水平安定面后梁中段裂纹和腐蚀问题,结合产品设计及制造工艺,采用断口显微分析、金相检验、硬度检测以及能谱分析等方法对该段裂纹形成的原因。结果发现:后梁中段裂纹性质为应力腐蚀裂纹,裂纹断口上存在的氯化物和硫化物为主的腐蚀产物;后梁中段在制造过程中表面防护层均有不同程度破损,LD5合金在富含Cl-的环境中经残余应力及工作应力的综合作用产生了应力腐蚀开裂。针对产生裂纹和腐蚀的各种因素,提出了切实有效的治理措施,将使该型飞机水平安定面后梁中段连接和防护状态更趋完善,保障机体寿命。

The intermediate section of the rear beam of an aircraft horizontal stabilizer was found to have cracks and corrosion after service for a while. The cause for the cracking was analyzed by macro and micro observation, metallographic examination, hardness testing, energy spectrum analysis as well as analyzing product design and manufacturing processes. The results show that the cracking mode is stress corrosion cracking. Sulfide and chloride corrosion products were found at the cracking fracture surface. The surface protection layer had been damaged during manufacturing process. The co-effect of residual stress and working stress resulted in the cracking of the LD5 aluminum alloy during service in the Cl-rich environment. Taking various factors of cracks and corrosion into consideration, several practical and effective measures were put forward to prevent this kind of failure and prolong the life of the aircraft body.