Systematic simulation based approach for the identification and implementation of a scheduling rule in the aircraft engine maintenance

Abstract

In the current situation of fluctuating demands and market driven turbulences, new part manufactures have to deal with many turbulence factors. Companies operating in the MRO (maintenance, repair and overhaul) sector have to additionally deal with major variations of work load and work contents. In addition, the operational processes of the maintenance contractors are strongly affected by the influence of the customers. The delivery date of the corresponding order is highly influenced by the customer. Besides the information about the actual work load is only completely known when the inspection is completed. Since the planning of the maintenance event and the maintenance operation are hard to handle, the focus of the approach presented in this paper is set on improving the maintenance operation by finding suitable scheduling rules for the job-shop operation of the maintenance. We hypothesize that the use of scheduling rules can improve the maintenance operation. The main question which is answered in this paper is the question if an improvement of the logistical targets of the maintenance system can be accomplished with the use of decentralized scheduling rules. As part of the examination, a systematic simulation based approach for the identification of scheduling rules is defined. Due to the need of different studies, a simulation model is developed. With this model, the different simulation studies can easily be accomplished. The simulation results show an influence of the decentralized scheduling before each of the machine tools. The best results were achieved by the combinations of FIFO/Slack and ESD/Slack with an influence on the target values on-time delivery, work in progress, the throughput, the performance and the throughput time.Further on a tool for the implementation of the identified scheduling rule in a decentralized shop control is described. Besides the validation of the tool in an aircraft engine company is made. The application of a Slack rule during a period with increased workload of 36% showed a nearly constant on-time delivery.