ABSTRACT
The vast majority of the successful designs have given considerable consideration to both reliability and maintainability. The degree to which these attributes are incorporated in a product determine the system effectiveness and customer satisfaction. The objective of designing for maintainability is to provide equipment and facilities that can be serviced efficiently and effectively and repaired efficiently and effectively if they should fail. Equipment should be designed with sufficient reliability so that it will be operable for an anticipated life cycle at optimum availability. Thus reliability is a function of design; once the design has been completed and released for manufacturing, the reliability of the product or system has been determined-it can not be altered without redesign. Functional designs, where the technology of maintainability has been given considerable consideration, will inevitably result in simplified maintenance that can be performed both effectively and inexpensively. Equipment will be down for service or repair for a considerably smaller proportion of the time, and the anticipated life of the equipment will be longer. Thus maintainability is a basic characteristic of equipment, and the need for maintainability is affected by its reliability characteristics. Since improving maintainability is both difficult and costly after development, it is extremely desirable that reliability re-
One must recognize that no product can be assumed to have 100% reliability at any point in its life cycle-even in the first minutes of its use. However, successful designs should have 100% maintainability.
