The Challenge - The expenditure of inspection, analysis, and maintenance resources on structural components can be somewhere between a necessity and an undue burden, depending on the role of the component in question and its importance in completing the mission of the structure. Throughout the design, fabrication, service, and retirement phases of life, tools are needed to help allocate these resources appropriately in order to ensure that the structural system is prepared to complete its mission while remaining safe and controlling costs.

Engineered Solution - AP/ES has been instrumental in developing a quantitative and qualitative process*, and applying it to systematically assist engineers in meeting this challenge. This process helps achieve the optimum life cycle cost of components by focusing the resources where needed, and allowing less significant structure to receive attention only when appropriate. Within each type and criticality of significant structure, criticality ratings and planned or actual usage data can be used to tailor actions and achieve the appropriate benefits.

Behind each of the tests (safety, mission, cost, readiness, and repair) analytical processes, design criteria, and maintenance/service history evaluations result in a qualitative and quantitative ranked assessment for each component. A prioritized list is then generated that optimizes the advantages afforded through improved design, structural health monitoring, inspection, and repair. Categories used for evaluation include operational and design stresses, stress spectra, and margins of safety; residual strength and load redistribution capabilities; safe-life and fail-safe design considerations; susceptibilities to various mechanical and environmental attacks; inspectability; accessibility; and costs thereof. This process can be tailored to any system (air vehicle, power plant, nautical, automotive...) or product where structural integrity is needed, optimization of service capability and costs are of concern, and proactive policies are embraced.

*Brooks, Craig, "An Engineering Procedure to Select and Prioritize Component Evaluation Under USAF Structural Integrity Requirements," USAF Structural Integrity Conference, 1990.