System reliability and condition based maintenance

The need for high system reliability and platform availability in DoD assets is an increasing necessity with the continuing combat deployment of service personnel coupled with the high usage rates for the equipment that they rely upon to complete their mission. In general, reliability is obtained through a variety of measures including precision design, reduction in the number of parts required for functionality and component/system redundancy. The availability of an asset is affected by both reliability and maintainability. There is a significant amount of anecdotal evidence that condition based maintenance enabled by embedded diagnostics and prognostics can directly improve maintainability but not reliability. The focus of this paper is to discuss the impact of reliability on key platform performance parameters and to compare the impact of embedded system health monitoring on those same key performance parameters. If the reliability of a component is defined by its capability to function to a required standard when requested, then health management technology should be able to provide the same benefit as increasing inherent reliability. If a functional but faulted component is replaced before it fails, when the platform is not required to be operational, then the availability of the component and the asset will be maintained or increased with the same inherent reliability. The paper discusses the requirements imposed on the embedded health monitoring system in terms of replacing investments in increased inherent reliability with investments in system health monitoring. This is a well known scenario, but difficult to implement effectively in a real world environment. The effort will require reliability engineers and health management technologists to work together to accomplish this common objective. The context for the application of this concept is the U.S. Army Heavy Brigade Combat Team - Condition Based Reliability Analysis (HBCT- COBRA) program. The objective of this program is to increase the reliability and availability of the HBCT platforms through implementation of embedded diagnostics, prognostics and CBM methodology.