Deep Dive into the F-35 Reliability Growth Plan

            The F-35 weapon system is being procured under a phased capability introduction strategy. Each phase is defined in the F-35 Air System Block Plan and expands the systems capability at each of the 11 Low Rate Initial Production (LRIP) batches. Currently delivering LRIP 5 aircraft, each batch or Block builds on the previous design and is intended to reach maturity by the end of LRIP 11. Key to this maturity is effective system enhancement through detailed Reliability and Maintainability (R&M) assessment.  Reliability growth during JSF Air Vehicle maturity will be achieved by the process of identifying, analyzing, and improving the Air Vehicle Mean Flight Hour Between Failure (MFHBF). This process will be implemented across the entire F-35 program with participation from Lockheed Martin, Developmental/Operational Test Teams, subcontractors, suppliers, and Operational Organizations. Performance and Maintenance data will be collected and analyzed to identifying candidates for reliability improvements.  Design improvement candidates are further evaluated to determine the best benefit versus cost to determine prioritization. Selected reliability improvement candidates have been and will continue to be recommended for incorporation into the design. This process uses an iterative, closed-loop reliability growth methodology.  This  includes testing, analyzing test failures to determine the root cause of failure, redesigning to remove the cause, implementing / incorporating the new design, and retesting to validate that the failure case has been removed (LM, 2011).

            Reliability does not improve as a result of planned changes.  Reliability grows, or improves, only as a result of incorporating effective design changes.  Once changes are incorporated, they must be validated to determine their effectiveness. The initial reliability depends on a number of factors, including product complexity, design maturity, design-to reliability guidelines and criteria, technology maturity, subsystem testing results, etc. (MIL-HDBK-189, 1981). The F-35 Program has implemented a closed-loop Failure Reporting, Analysis, and Corrective Action System (FRACAS) that includes inputs from suppliers, subcontractors, testing activities, and operational organizations.  F-35 Joint Program Office (JPO) R&M managed Joint Reliability Maintainability Evaluation Team (JRMET) is established to assist in the collecting, reporting, analyzing, and categorizing (utilizing the FRACAS application) of reliability data in support of Developmental Test and Evaluation (DT&E), Operational Test and Evaluation (OT&E) (JARMET Charter). There are two objectives of statistical analysis of this data. Firs, determine if reliability growth is being achieved according to planned growth. Second, identify the equipment failure rates and patterns to focus engineering and management activities to ensure that the contractual MFHBF values are achieved (JARMET Charter).

            Reliability growth analysis results and tracking status is reported, along with the status of reported failures and of recommended and implemented corrective actions.  Open items are highlighted for initiation of closure action.  A “Top Contributors” chart, commonly known as the R&M top 100 list, is maintained for visibility and to prioritize the corrective action process. Monthly reports summarize the results of the reliability growth tracking analysis as compared to the corresponding planned growth value. (JSF Reliability Growth Plan, 2011).

             The F-35 Reliability Growth Plan is based on a program wide data collection initiative designed to validate predicted performance as well as drive engineering chances to ensure system maturity, As stated last week, instability in aircraft design, system maturity, and performance reliability negatively impact an acquisition program. Each of these factors are even more programmatic under concurrent development programs like the F-35.    

References:

Duane, J. T., ''Learning Curve Approach To Reliability Monitoring'', IEEE Transactions on Aerospace, Vol. 2, pp. 563-566, 1964.

Kececioglu, Dimitri, B. (1991). Reliability Growth, Reliability Engineering Handbook, Ed. 4, Vol. 2, Prentice-Hall, Englewood Cliffs, New Jersey.

Joint Reliability Maintainability Evaluation Team (JRMET) and Test Data Scoring Board (TDSB) Charter. (2007, May 17). Appendix Updates:  E ~ I.

Lockheed Martin (LM). (2011, March 30). JSF Reliability Growth Plan. Internal Doc. No. 2ZZA00026

MIL-HDBK-189. (1981, February 13). Reliability Growth Management. Retrieved from: http://www.barringer1.com/mil_files/MIL-HDBK-189.pdf