Optimization of Shop Visit for Aeroengine Using the Proportional Hazard Model

According to the definition given by the world airlines technical operations glossary (WATOG), an aeroengine removal is classified as a shop visit (SV) whenever the subsequent engine maintenance performed before reinstallation entails separation of pairs of major mating flanges or removal of a disk, hub, or spool. Considering the high cost of both purchase and maintenance of the aeroengine, it is necessary to optimize the SV decision to decrease quantities of spare engines and the number of SVs for the aeroengine. Therefore, by making full use of monitoring data in aeroengine and adopting just-in-time theory, an optimization method of SV for the aeroengine using the proportional hazard (PH) model is proposed. First, a Weibull PH model for aeroengine is established to predict the remaining useful life (RUL), and the parameters are estimated with the method of principal component analysis and genetic algorithm. Second, an SV decision policy is proposed and the optimization model of SV decision is established based on the RUL to minimize the expected cost rate. Finally, a case study on a specific aeroengine is conducted to demonstrate the effectiveness of the proposed method. Results show that the prediction of RUL based on the proposed PH model has a low prediction error and the process of SV decisions is dynamic and feasible to obtain the optimal SV decision.