On reliability criteria and the implied cost of failure for a maintained component

This paper considers age-based replacement and block replacement when reliability is also a decision criterion. We describe how specification of the operational reliability of component function determines the replacement policy, and that setting a value for the cost of failure and specifying an operational reliability requirement are equivalent. This duality then implies a simple method for checking the consistency of the cost of failure and operational reliability measures when they are set system operators and maintainers. A simple expression for the median time between operational failures for a socket subject to age-based replacement is also obtained. These ideas are considered briefly in the context of block replacement. Data from an actual case relating to the maintenance and replacement of train traction motors is used for illustration.