The concept of Reliability Centered Maintenance (RCM) originated in the airline industry, where the cost of safety-driven, failure preventive servicing programmes and poor aircraft availability prompted the need for a new approach to maintenance.

Reliability centered maintenance has been defined as “A systematic approach to quantitatively assessing the need to perform or revise preventive maintenance tasks and plans”.

It provides slightly focused methodology which is targeted on systems function, the failures relating to that function and in particular to the effects of dominant functional system failures. A decision tree is used within RCM to identify and classify critical system components together with an appropriate and applicable maintenance policy. The main concept underlying the development of RCM is, an attempt to retain the designed reliability of equipment, through the analysis so factors which affect its operating reliability, and with a view to optimizing preventive maintenance programmes via effective maintenance planning .Thus the main objective of RCM is the cost – effective maintenance of equipment’s inherent reliability value. It does so by utilizing the principal justification criteria of safety. Availability and cost –effectiveness to decide what maintenance should be undertaken to achieve the deferral or prevention of specific failure modes .

Reliability centered maintenance is implemented via. twin analysis routines investigating the system design. One analysis seeks to identify the origin of potential failure modes and their probability of occurrence, whilst the other develops the decision logic for each mode, and provides the Formulation structure necessary to determine the nature of the scheduled maintenance tasks required. The two major aspects of RCM are therefore;

• The determination of a maintenance requirement and the identification of the tasks necessary to satisfy it.
  
  
• The reliability analysis of critical system components and hence the determination of the maintenance task interval.
  

Evaluation techniques such as failure mode effects and criticality analysis (FMECA) or fault tree analysis (FTA), are used to determine failures, which may affect the operational capability of the equipment thereby disclosing the significant maintenance tasks. In addition, by partitioning the equipment into object categories, significant items can be identified, which through intensive decision theory (DT) analysis permit the determination of maintenance actions. As with scheduled maintenance, the intervals between maintenance tasks are estimated, using ‘a prior’ statistically failure data and a knowledge of the appropriate probability distribution. Reliability centered maintenance provides a useful cast control methodology whilst simultaneously maintaining the inherent reliability of the equipment. In addition, the analyses used in RCM provide a means by which any inherent equipment design failures may be located. Whether scheduled maintenance is required, the time interval for such maintenance and what the maintenance tasks may be, considerable cost savings are claimed for this approach to maintenance along with optimum repair effort, maximum safety and high productivity.