Analysis of Cracking of Main Lift Unlocking Actuator Cover of a Type of Landing Gear
In order to accurately locate the cracking cause of a certain type of landing gear in the external field,it was a-dopted that the five-step analysis method of accurate positioning,clear mechanism,problem recurrence,effective measures and drawing a conclusion.The multi-angle fault analysis was carried out that the visual inspection,the microscopic observa-tion,the fracture components analysis and microstructure detection of the three plug cover faults.The two lock actuator components were randomly selected and salt spray test was carried out according to the drawings and design requirements,and the fault phenomenon was successfully reproduced through tests.It was found that the failure mechanism of plug cap cracking as follows:after the corrosion medium was deposited in the outer cylinder thread of the main unlock actuator cover,once the protective film on the thread surface was damaged and the radial stress during assembly was too large,the flow line at the mold surface of the plug cap was easily exposed,and the exposed grain boundary became a corrosion channel,which finally caused stress corrosion damage along the grain boundary.In order to solve the problem of stress corrosion cracking of the plug cap,the angle of parting die surface in the process of die pressing of end cap was improved,and the fixed torque method was adopted in the assembly of unlocking actuator barrel to control the assembly stress and prevent similar problems from happening again.
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