Statistics for Maintenance Modelling: Repairable Systems

# Introduction¤

A repairable system is one which after failing to function properly may be restored to satisfactory working order by replacing or repairing certain components except replacement of the entire system. The system will, throughout its lifetime, undergo alternating in-service times and repair/maintenance times. In practice many systems are of this type. Examples featured in this session are:

- motor vehicles
- air-conditioning units in an aircraft
- main propulsion diesel engines of USS Grampus
- some software during the production and testing stages.

Of interest are the times of failures and the costs incurred, both of which may be plotted against time to reveal patterns and any unusual features of the data. Repair and maintenance times may also be of interest, but it will be assumed initially that these are small relative to the in-service times.