Using PHM to meet availability-based contracting requirements

"Availability-based" contracting originated because customers with high availability requirements are in many cases interested in migrating from buying the actual system to buying the availability of the system. A well-known example of availability-based contracting is Performance Based Logistics (PBL). Prognostics and Health Management (PHM) methods are incorporated into systems to avoid unanticipated failures that can potentially impact system safety, result in additional life cycle cost, and/or adversely affect the system availability. While predicting the availability of a system based on known or predicted system parameters is relatively straightforward and can be accomplished using existing methods; determining the system parameters that result in a desired availability is not and is generally performed using "brute force" search-based methods that become quickly impractical for designing systems with more than a few variables and when uncertainties are present. This paper presents the application of PHM within a "design for availability" approach that uses an availability requirement to predict the required logistics, design (including reliability) and operation parameters with and without the application of PHM methods. A life cycle cost analysis is used to quantify trade-offs of using PHM methods versus more traditional maintenance approaches in the context of availability contracts.