The product lifecycle of a technical system is often longer in practise than the availability of spare parts. Every day, manufacturers worldwide are discontinuing products, so their end of life is announced. This affects not only the systems manufacturer but largely the operator of the plant. The machine down risk for a defective component within the system increases. While it was common practise a few years ago to stock critical components, it was soon removed in respect of warehouse costs and the tied-up capital and replaced by just-in-time inventory availability by the manufactures or distributors.