9. Summary

The aim of this article was to introduce the concept of availability of means of production.

We have seen that availability cannot be assessed "en bloc".

It is the result of many factors: reliability, maintainability, preventive maintenance, spare parts, sizing and efficiency of maintenance teams...

It should be remembered that part of availability is created at the design stage; this is the part resulting from the two components of reliability and maintainability. The other part of availability is related to the organization or the user's choices.

We also encountered a few paradoxes:

• Preventive maintenance is a means of ensuring a suitable level of reliability, and therefore of improving availability, but equipment becomes unavailable during preventive maintenance...