1. Basic concepts

1.1 Notion of maintainability

Maintainability is a characteristic specifying the ease and speed with which a system can be restored to full working order with a reliability corresponding to its age.

The speed with which a system can be restored can be measured by the active troubleshooting time. By active, we mean that dead times not attributable to the system's design, such as repairer response times, waiting times for spare parts or time spent drafting administrative documents, will not be counted, as these times depend on the organization and efficiency of the maintenance department and not on the system's design.

In order to make troubleshooting easier and quicker, the design must include the means to facilitate :

...