| This thesis studied the corrosion on the keel beams ADF antenna installationarea of Boeing737CL, which is popular in China civil aviation.and tried to find outan effecient measure to prvent and control the corrosion. The main goal of this thesisis preventing the corrosion from endangering the safety of Boeing737CL and reducethe airplane maintenance cost.This thesis confirmed the corrosion type on the keel beam by means of SEM,TEM, and X-ray energy dispersive analysis, which includes Pit corrosion,Exfoliation corrosion and Stress Corrosion Crack. The three developing stages of thecorrosion have also been confirmed, which inclue Pit corrosion on the surface at firststage, Exfoliation corrosion in the layer next to the surface on the second stage andStress Corrosion Crack in the intermediate layer at last stage. According to thecorrosion mechanism, the advanced corrosion prevention guidelines of airplanestructure designing and maintenance in Europe and America civil aiviation and thestructure configuration of the keel beam, the defects of structure designing andmaintenance on the venting&draining, sealing, surface finish, stress control andcorrosion inhibitor application were identified. Based on the defects of the structuredesigning and maintenance, the advanced civil aircraft structure maintenance theoryof MSG-3and the designing guidelines, this thesis proposed the corrosionmaintenance program and the designing improvement suggestions on venting&draining, sealing, surface finish, stress control respectively.The corrosion maintenance program in this thesis has been used in the Boeing737CL fleet of Hainan Airline. The corrosion on the keel beam has been controlledeffectively. The result shows that the corrosion maintenance program in this thesis isworth promoting in Civil Aviation of China. The corrosion maintenance program andthe designing improvement suggestions in this thesis can also be introduced into theairplane designing and maintenance document development of those civil airplanesdesigned by China, such as D-600，M700and C919etc. |
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