AVAILABILITY RESILIENCE FOR SYSTEM SUSTAINMENT LEVERAGING HIERARCHICAL STRUCTURES

Abstract System sustainment is an important component of system deployment and use because it ensures systems continue to deliver value throughout their operational life cycle. Complex, long‐lived systems incur the most cost during the sustainment period of their life cycle. The sustainment of these systems is heavily dependent on component availability and the support of the supply chain. Naval and defense industries have long‐lived systems where accurate prediction of system availability is not only critical to managing diminishing manufacturing sources and materials shortages, fleet sustainment, and system resilience, but also to reducing the total cost over a system's life cycle. Availability resilience defines how resilient a system is against unavailability; it is how a system responds to unexpected adverse events such as breakdowns in supportability, reliability, and maintainability. The data used in system availability resilience calculations is primarily focused on the part‐level. The Hierarchical Availability Resilience Tree (HART) algorithm leverages existing digital configuration structures, such as reliability block diagrams, and fault trees to mathematically model system availability resilience while overcoming the lack of intermediate data. This paper modifies the HART algorithm to allow for system‐level availability resilience calculations in the absence of existing digital configuration structures. This HART modification utilizes a system's bill of materials and subject matter expertise to create the availability resilience tree. Analysis of the availability resilience variables is also explored. The modified HART algorithm and the variable analysis advances modeling techniques to improve life cycle affordability and enable system readiness optimization.