An Integrated Maintenance Overhaul Scheduling and Inventory Control Model with Multiple Stages and Quality Categories

Airline companies and MRO (Maintenance, Repair, and Overhaul) service providers often engage in exchange programs to minimize downtime caused by long MRO processing times. These programs allow airlines to acquire already-overhauled modules from the ready-to-use inventory of MRO companies. Extracted modules from aircraft, known as rotable modules, are overhauled and returned to the MRO company’s inventory for future exchanges. Although exchange orders and their deadlines may be predefined, it can sometimes be more cost-effective for the MRO company to perform module exchanges before these deadlines, despite potential earliness penalties, due to operational capacity constraints and inventory costs. Moreover, exchange modules vary in quality and age, requiring additional transfer fees between the MRO service provider and the customers to compensate for these differences. In this study, we address the joint problem of overhaul planning and exchange scheduling from the MRO company’s perspective. We propose a mixed-integer programming model aimed at minimizing the total cost of earliness penalties, switching, procurement, and inventory. We introduce a valid constraint to enhance computational performance, accelerating the search for an optimal solution. Through comprehensive numerical analysis, we evaluate the model’s computational performance and derive managerial insights on how key parameters influence optimal scheduling and inventory decisions.