^aOptimized Systems & Solutions, 230 Bristol Business Park, Bristol BS16 1FJ, UK

Abstract

The reliability of most mechanical and electronic systems has improved dramatically over the past 50 years and yet there are warehouses full of spare parts that will never get used because there is no demand, or because they will reach their use by a date before they are needed or because they will become obsolete. Parts are frequently replaced unnecessarily while others that are much more likely to cause system failures are left untouched. The result is that despite vast sums of money being invested in spares, system availability is still very much a problem. Operations research has the tools that could significantly improve this situation but why are they not being used?