Maintainability engineering is rapidly growing in importance because of its considerable contribution towards the reduction in maintenance costs of a product during its operation. At the same time maintainability theory provides a very powerful tool with which to provide engineers with a quantitative description of the ability of their products to be restored to working order, by performing appropriate maintenance tasks.

Reliability Centred Maintenance (RCM) has success stories around the world and the following facts and figures were given courtesy of QARS, TACS and DataTeam.

Typical Benefits:

- Reduction in spares inventory of 20-25%
- Reduction in maintenance costs by up to 40%
- Reduction in new spares purchased of 10-15%
- Improvement in plant availability by up to 15% and
- Improvement in equipment reliability

RCM has been named to emphasise the role that reliability theory and practice plays in properly focusing (or centering) preventive maintenance activities on the retention of the equipment's inherent design reliability. As the name implies, then, reliability technology is at the very center of the maintenance philosophy and planning process.

RCM breaks down into four steps for analysis

- Assets Criticality Analysis (ACA)
- Failure Modes Effects Analysis (FMEA)
- Failure Characteristic Analysis (FCA)
- Maintenance Strategy Selection (MSS)

RCM ensures that both today and in the future, the engineer understand "why" each task in maintenance is important, so no effort is wasted on doing what is meaningless.

RCM ensures that the task selection derives from a comprehensive knowledge of equipment failure modes because it is at that level of detail where failure prevention, detection, or discovery must occur. If the tasks selection process, whatever it may be, does not do this, then there is no assurance that the task really does anything particular useful.

RCM ensures that the most effective (least costly) task is chosen for implementation.