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