Effect of Improving Accuracy of Load Monitoring on Aircraft Probability of Failure

Evaluating risk of aircraft failure is necessary for scheduling appropriate maintenance, avoiding aircraft losses and mission failures, maintaining a high level of readiness, and estimating aircraft fleet aging. This paper presents the results of calculating aircraft failure risk by estimating the probability of structural failure of F-18 wing attachment bulkheads. Laboratory fatigue-crack growth-test data (published in open literature) are utilized to describe the distribution of initial defects, which is then evolved as a function of applied loads and flight hours. The risk is calculated as a probability of failure (POF) during a single flight, and it is shown that the effect of uncertainty in the knowledge of applied flight loads on POF is significant. The reported results provide a framework for evaluating benefits of improving accuracy of load-monitoring data and POF.