Multi-Echelon Inventory Allocation under Imperfect Repair for Repairable Spares of Civil Aircraft

Because the repairable spares of civil aircraft after repair are not as good as new, and therefore causes performance deterioration progressively and scrapped after a certain number of maintenance, which current spare parts inventory optimization models cannot describe it accurately. Focus on this problem, this paper proposes the multi-echelon inventory allocation method under imperfect repair combined with quasi renewal theory, queuing theory and Vari-Metric model. At first, simulate of deterioration process based on quasi renewal theory and get the amount of scrap. Then, considering the working hours after maintenance is shortened and the maintenance time increased gradually, the M/M/c/m+S/m queuing theory model is adjusted to get the demand of repairable spares. On this basis, this paper introduces scrap stream and extends Vari-Metric model for the obsolescence of spare parts. Afterwards, obtaining biggest economic benefits with minimal investment costs is selected as objective, marginal analysis method is set as the optimization to solve the model and get the allocation scheme of repairable spares. Through the example analysis, the result shows the proposed method can provide effective reference for the spare parts support decision of civil aircraft's total life-span cycle.