Abstract
Considering the wide application of condition-based maintenance in aeroengine maintenance practice, it becomes possible for aeroengines to carry out their preventive maintenance in just-in-time (JIT) manner by reasonably planning their shop visits (SVs). In this study, an approach is proposed to make aeroengine SV decisions following the concept of JIT. Firstly, a state space model (SSM) for aeroengine based on exhaust gas temperature margin is developed to predict the remaining useful life (RUL) of aeroengine. Secondly, the effect of SV decisions on risk and service level (SL) is analyzed, and an optimization of the aeroengine SV decisions based on RUL and stochastic repair time is performed to carry out JIT manner with the requirement of safety and SL. Finally, a case study considering two CFM-56 aeroengines is presented to demonstrate the proposed approach. The results show that predictive accuracy of RUL with SSM is higher than with linear regression, and the process of SV decisions is simple and feasible for airlines to improve the inventory management level of their aeroengines.
Highlights
Both purchase cost and maintenance cost of civil aeroengines are very expensive
In this study, according to the concept of JIT, the remaining useful life (RUL) of aeroengine would be predicted and be applied to make shop visit (SV) decisions to avoid the overlap of SVs and reduce the number of spare aeroengines; stochastic repair time of aeroengine is considered as a major factor during making SV decisions
The effect of SV decision on risk and service level (SL) should be analyzed, and aeroengine SV decisions should be optimized based on RUL and stochastic repair time, in order to minimize the number of spare aeroengines and to maintain required safety and SL
Summary
Both purchase cost and maintenance cost of civil aeroengines are very expensive. For example, CFM56-5 is about 4.5 million dollars, and its shop visit (SV) cost is up to one million dollars per visit [1, 2]. With the development of condition-based maintenance (CBM) in aeroengine maintenance practice, it is possible to implement the concept of JIT through reasonably planning the aeroengine SVs by considering an essential condition that the previous aeroengine will return from the shop before the aeroengine needs a spare aeroengine. In this study, according to the concept of JIT, the RUL of aeroengine would be predicted and be applied to make SV decisions to avoid the overlap of SVs and reduce the number of spare aeroengines; stochastic repair time of aeroengine is considered as a major factor during making SV decisions. The effect of SV decision on risk and service level (SL) should be analyzed, and aeroengine SV decisions should be optimized based on RUL and stochastic repair time, in order to minimize the number of spare aeroengines and to maintain required safety and SL. A case study using real data is developed, and the conclusions from the work presented in this study and suggestions for future research are given
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