Corrosion Risk Assessment of Aircraft Structures

Abstract This paper presents a comprehensive summary of IAR/NRC research on risk assessment of aging aircraft structures in the presence of corrosion and fatigue. Extensive test data, especially for fuselage splices containing corrosion and multiple site fatigue damage (MSD) and coupons cut from service exposed aircraft lap joints, have been generated under previous projects. Based on these test data, an empirical stochastic crack growth model was first developed to analyze the probabilistic fatigue characteristics of the splices. Risk analysis was then performed on the fuselage splices using the computer codes PRISM (Bombardier Aerospace, Inc.) and PROF (United States Air Force). Holistic life assessment methodology (HLAM), which aims to quantify structural integrity in the entire life cycle by addressing the interaction effects of corrosion and fatigue, has advanced considerably during the past five years. Risk analysis based on HLAM was carried out on the fuselage splices. The analytical results, which were obtained at different stages, are compared with the test results. It is shown that corrosion in lap joints, even at the levels less than the typical maintenance limit (i.e., 10 % material loss), could significantly increase the risk level of structural failure.