Availability Modeling and Analysis of Multi-Fleet Aircrafts Basing on Inventory Network of Different Transshipment Policies

In this paper, in order to provide solution to availability analysis of multi-fleet aircrafts, spare parts transshipment of the multi-fleet aircrafts which is analogous to inventory network. Based on mathematical models, the influence of transshipment policies on the total backorders and availability of the multi-fleet aircrafts is studied. According to the consumption and replenishment process of the spares under certain inventory control strategy, the steady state equations of inventory network are given under Random Policy and Priority Policy. By defining constant coefficients, the original model equations are transformed into linear equations, and then the uniqueness of the solution is proved on the basis of the criteria for determining solutions of linear equations. And next, an iterative algorithm is designed to obtain the solution of the equations and is verified by a case. Finally, the comparative analysis of models under the Random Policy and Priority Policy are executed. Results show that the Priority Policy is superior to the Random Policy on the sharing rate of spares and availability of multi-fleet aircrafts. But only when the parameters are consistent with the priority constraints, that is the higher priority of the site, the more spares on hand, the advantage can be achieved. Or the advantage will be reduced or even reversed.