Risk-based maintenance optimization of aircraft gas turbine engine component

Abstract

The integrity of an aircraft gas turbine engine is critical for safety of flight. Although the reliability of engines has improved considerably, a large number of legacy engines continue to operate. The maintenance of legacy engines is a major burden for their operators owing to the high cost involved, and the engines pose a high risk to flight safety. In this study, we developed a comprehensive approach for risk-based maintenance optimization of aircraft engine components. The approach involved the use of a physics-informed data-driven model incorporated with the Weibayes model and a simple fatigue crack growth model. The crack length distribution and corresponding risks were evaluated using Bayesian updating and knowledge of nondestructive inspection reliability. The model was used for the computation of the fatigue reliability of the first-stage blisk of a CT7-9C turboprop engine. A single failure was used for the Weibayes analysis, and a master crack growth curve was obtained through quantitative-fractography-based crack growth analysis. Furthermore, an inspection model based on the evaluation of field inspectors was used to obtain the posterior crack length distribution, and through a sensitivity analysis, important factors were identified. Finally, optimal inspection and replacement plans were formulated using approximated objective and constraint functions. In particular, the life-cycle cost was minimized while maintaining the risks within strict limits.