Airframe corrosion probabilistic modelling and reliability

Corrosion has been one of the most serious safety problems in aviation, and the most costly maintenance problem. Contributing to the problematic nature of corrosion is the complexity of its mechanisms and the randomness with which it occurs. The reliability of a structure affected by corrosion is normally based on the forms of the erosion and its severity. Existing research in this area has a primary focus on corrosion induced structure failure due to inadequate residual structural strength. However, it is valuable to recognise that some product failures induced by corrosion are not critically dependent on stress or fatigue-examples include such cases as leakage from oil pipe or containers, leakage into air cabin and landing floats and, or degradation of a high smooth surface required structure. In such cases non-structural failure should be judged on some specific failure criterion involving the number of corrosion spots, as well as their surface area, depth and distribution. Based on data collected from inspection and maintenance records of the Chinese Yunshu-7 passenger aircraft, this paper will propose some new concepts formulation of relevant failure criteria and will propose corrosion probabilistic models for reliability assessment.