Interval Availability Analysis of a Two-echelon, Multi-item System

In this paper we analyze the interval availability of a two-echelon, multi-item spare part inventory system. We consider a scenario inspired by a situation that we encountered at Thales Netherlands, a manufacturer of naval sensors and naval command and control systems. Modeling the complete system as a Markov chain we analyze the interval availability. We compute in closed and exact form the expectation and the variance of the availability during a finite time interval [0, T]. We use these characteristics together with the probability that interval availability is equal to one to approximate the survival function using a Beta distribution. Comparison of our approximation with simulation shows excellent accuracy, especially for points of the distribution function below the mean value. The latter points are practically most relevant. 1 Corresponding author email: [email protected] (Ahmad Al Hanbali) 2 School of Management and Governance, P.O. Box 217, 7500 AE Enschede, The Netherlands.