Maintainability Analysis

At the equipment and system level, maintainability has a significant influence on reliability and availability. This is particularly true if redundancy has been implemented and redundant parts can be repaired on line, i.e. without interruption of operation. Maintainability thus represents an important parameter in the optimization of reliability, maintainability, and life-cycle cost. Achieving a high maintainability target requires appropriate activities which must be started early in the design and development phase, and be coordinated by a maintenance concept. To this belong fault detection and isolation (built-in tests), partitioning of the equipment or system into almost independent last repairable units (spare parts at equipment or system level), and logistical support (also including after-sales service). Because of the diversity of equipment and systems as well as maintainability requirements, a maintenance concept must generally be tailored to the specific project considered. After a brief discussion of the basic terms, this chapter introduces the maintenance concept as applied to complex equipment and systems, and deals then with maintainability calculation techniques and basic models for spare part provisioning. Design guidelines for maintainability (including testability) are given in Section 5.2.