Spare parts inventory control model for the aeronautical industry

Inventory management of spare parts is one of the most critical issues in the aeronautical industry, given the required level of system availability related to the strategic importance and high stocking costs of the components. A failure of any item on an aircraft could determine its unavailability, so spare parts are in stock in order to reduce the unavailability period and provide a prompt substitution. Therefore the allocation of spare parts is subjected to budget constraints and to a target level of availability. Even if a large number of spare parts increases warehousing costs, every single shortage have a greater impact: the adoption of best-in-class inventory management techniques becomes crucial. On these considerations, the paper presents an innovative model of spare parts allocation developed for an Italian airline with the aim of minimizing back orders and, at the same time, ensuring an availability of 99% depending on the actual flight plan. Starting from the assumptions of VARI-METRIC, the model considers an original configuration of features combining different skills of maintenance centers in a hierarchical multi-echelon, multi-item, multi-indenture structure. It will be solved by an optimization tool with the aim of identifying which spare parts must be stocked in the warehouse at all times and which ones can instead be ordered only when an actual request is raised, with respect to a cost analysis. The process is based on a real case which evaluates the historic yearly demand and an assessment of the times related to repairing, order and shipment for each item, for each site.