Practical application of structural risk assessment with SMART DT

Structural risk assessments are highly relevant to assure the structural integrity over the whole life-cycle of an aircraft. The Aircraft Structural Integrity Program (ASIP) from the US Air Force introduces design guidance based on deterministic crack growth prediction for safety critical components. Today, with the increase of computational power, probabilistic methods instead of deterministic analysis can be deployed. Probabilistic Risk Assessment (PRA) offers the benefit of taking uncertainty into account and leads to less conservative estimates while meeting safety requirements. Research organizations such as the National Research Council Canada (NRC) or the Defence Science and Technology Organization in Australia (DSTO) are already assessing safety critical elements with PRA. RUAG AG is interested in the application of this method for current and future military aviation systems. Based on the research performed by these organizations, the application of PRA is assessed. The probabilistic calculations are performed with the software tool SMART|DT. Structural engineering and fatigue data is needed for such an assessment, which includes equivalent crack growth data, pre-crack size distributions (EPS), loading distributions and probability of detection (POD). The possibilities of the tool are demonstrated with a case study from the Swiss F/A-18 fleet at knife edge of inner wing trailling edge flap hinge. The results will be compared with analyses from ProDTA from NRC and with PROF from the United States Air Force (USAF).