Improving reliability of repairable systems using preventive maintenance and time-between-failures monitoring

The purpose of this article is to investigate how to assess the rate of occurrence of failure (ROCOF) of a multi-component repairable system and improve its reliability. A procedure was developed and tested on closed-circuit television dome cameras operated in an airport in the United Arab Emirates. Optimum replacement times for critical components were calculated, and then a practical preventive maintenance schema was suggested to reduce the overall cost. Finally, a control chart was developed to monitor the time between failures (TBFs) on the basis of the calculated ROCOF. The results of the case study show that optimising the maintenance renewal intervals generated a saving of approximately 77% in maintenance costs, reduced the ROCOF by approximately 94%, and increased the level of planned maintenance by approximately 97%. Furthermore, monitoring the TBFs of repairable systems could detect changes that might lead to failures over time, thus improving the reliability and ensuring the effectiveness of preventive maintenance.