State dependent spare part management policy for airport maintenance

In this study we use a flexible policy of spare part management in the context of airports corrective maintenance activities and provide a new approach for mathematically evaluate the performances of systems with lateral transshipments in case of one-for-one ordering policies, transfer times and peaked demand. This study deals with the spare optimization of a large logistics company, in charge of the maintenance of 38 Italian Airports. Strict requirements of equipment operational availability and long repairing times make necessary to maintain high stock levels of spare parts, thus involving high inventory costs. While a two echelon inventory policy without lateral transshipments is currently applied, more flexible models with lateral transshipments might help to reduce inventory levels. We show the potential benefits deriving from implementing a single echelon policy with extensive use of lateral transshipments. The resulting model is a queueing network with zero buffer and lateral demand. The blocking probability of this network models the probability of spare part unavailability. We show that the probability of spare parts unavailability in the network can be easily computed using a Markov chain model. The system operational availability is then computed with two heuristic algorithms. The behavior of the two heuristics is very reliable if compared with that of the Markov chain model. Computational experiments, carried out with the proposed algorithms, show that the single-echelon policy under study allows to satisfy operational availability constraints with a significant reduction of spare stock levels with respect to the two echelon policy.