Corrosion failure analysis of nuts and locking device assembly at airliner hatch door rods

Abstract

Alloy steel and stainless-steel possess properties such as high strength, easy processing and outstanding mechanical properties after cadmium electroplating. They are widely used in aerospace, automotive and construction fields. However, the above steel parts are prone to be susceptible to hydrogen embrittlement, corrosion and other aging phenomena, resulting in the reduction of the flight safety factor. In this work, based on the actual situation of corrosion of the cadmium plating layer of cargo door rods and boarding gate/service hatch door rods, the cadmium acetate (short for (CH3COO)2Cd) leads to the failure of the jam nuts and locking device assembly, the cause and mechanism of the corrosion in the storage environment are analysed. Compared with the slightly corrosion jam nuts (19.18 kN and 370 HVI), the tensile property and hardness of the jam nuts with serious corrosion respectively decreased to 17.39 kN and 417 HVI, by 10.10% and 3.8%, which will reduce performance impacts on the safe flight and daily maintenance of aircraft. By improving the warehouse storage environment and operators’ specification documents, these problems have been avoided, and experience has been provided for parts anti-corrosion and batch production of airliner route operation.