System Health Assessment

Complex systems are increasingly confronted by two conflicting sets of requirements: on the one hand, demands for continuous operational readiness with high reliability and availability; on the other, the need to minimize life cycle cost, implying reduced inspections, maintenance, and logistics support. An emerging paradigm to address this challenge is prognostics and health management (PHM), where measures of system health are used to determine needs for preventive and corrective maintenance, to optimize maintenance scheduling and parts stocking, and to forecast when a system will reach the end of its useful life. Two key components of PHM are a definition of system health and a strategy for how it is to be measured as part of system health assessment (SHA). In this article we discuss system health as a general concept, illustrate its application with examples, and describe how the use of system health metrics as part of an SHA program can facilitate PHM.