How do you design a system that is easy, quick, and cost-effective to repair when it fails? Reliability engineering, as discussed earlier, participates in the design process to produce a system that is as failure-free as possible. Maintainability engineering also participates in the design process, but its effort is focused on making system as easy and inexpensive as possible to test, service, and repair when it does fail. The goals of maintainability engineering are to provide input into the design process in the form of design criteria that result in a system design in which it is easy to identify faults, requires minimum personnel and other logistics support resources to perform maintenance, and has the lowest life-cycle cost possible. The concepts used by maintainability engineering to accomplish these goals, such as modeling, allocations, predictions, and testing, are very similar to those used by reliability engineering. Many of the results of reliability activities are used by maintainability engineers, which will become evident later in this chapter.

The initial task of maintainability engineering is to develop predictions of how long it will take to repair the system when it fails. Using these predictions, the design can be analyzed to identify possible changes that would reduce the time required to perform maintenance. As the design matures, the maintainability aspects of the system can be determined through actual testing and demonstration of maintenance actions. The combination of system reliability, how often it will fail, and system maintainability, how long it takes to...