Assessing the impact of health management approaches on system total cost of ownership

The Integrated Diagnostics 1,2 and Integrated Vehicle Health Management (IVHM) processes provide frameworks that seek to maximize product availability and simultaneously reduce total system ownership costs. A System Engineering approach is required to balance system requirements and design goals with effective implementation methodologies throughout the system acquisition life cycle. Prediction of failures (or prognostics) is just part of an effective, integrated Health Management solution. Implementation of an efficient methodology will achieve a balance of health management technologies - the right mix of diagnostic, prognostic, and scheduled maintenance approaches based on available resources and Life Cycle Cost considerations. This paper focuses on means for assessing the impact of potential Health Management approaches on Life Cycle Cost (LCC) as implemented within a System Engineering framework. A disciplined approach to selecting appropriate Health Management solutions to satisfy design and operational requirements will be presented, and a software tool for performing trade studies of alternate approaches' impact on Life Cycle Cost will be discussed. This tool, the Ownership Cost Calculator for Aerospace health Management (OCCAM), is designed to assist engineers in evaluating LCC impact of multiple Health Management approaches and design solutions. It takes an innovative and rigorous approach to modeling maintenance and logistics costs associated with aircraft failures, and provides a high fidelity model that permits comparison of the impact of alternative solutions (such as diagnostic, prognostic, or scheduled maintenance approaches) to aircraft Total Cost of Ownership. Cost influencing parameters are based on standard or customizable fleet mission profiles and economic factors, as well as part failure, maintenance and logistic processes. Three versions of the tool have been produced to fit the logistic needs of the application domain: Commercial Airplane, Military Aircraft (fixed wing and rotorcraft) and Space (manned orbital missions). The outputs from the tool answer standard business questions such as "What is the projected Return on Investment?" and "What is the Breakeven Period?" A means to determine analysis sensitivity to various system input parameters and perform "what-if" analyses is also provided. A primary goal was to allow domain experts and health management specialists to perform thorough Life Cycle Cost analyses without requiring the services of specialized cost analysts. OCCAM has been successful in this respect, with initial applications providing immediate payback. A patent application was filed in 2004.