Enhancing MIL-HDBK-217 reliability predictions with physics of failure methods

The Defense Standardization Program Office (DSPO) of the U.S. Department of Defense\´s (DoD) has initiated a multiphase effort to update MIL-HDBK-217 (217), the military\´s often imitated and frequently criticized reliability prediction bible for electronics equipment. This document, based on field data fitted empirical models, has not been updated since 1995. The lack of updates led to expectations that its statistically-based empirical approach would be phased out. Especially after science-based Physics of Failure (PoF) [a.k.a. Reliability Physics] research led Gilbert F. Decker, Assistant Secretary of the Army for Research, Development and Acquisition to declare that MIL-HDBK-217 was not to appear in Army RFP acquisition requirements as it had been "shown to be unreliable and its use can lead to erroneous and misleading reliability predictions". Despite such criticism, MIL-HDBK-217 is now being updated as part of the recent climate within the DoD to reembrace RAMs methods [2+3]. This paper reviews the reason for the document\´s revival and update along with the primary concerns over its shortcomings. The team working to update MIL-HDBK-217 developed a proposal for resolving the limitations with empirical reliability prediction. A hybrid approach was developed where improved and more holistic empirical MTBF models would be used for comparison evaluations during a program\´s acquisition-supplier selection activities. Later, science-based PoF reliability modeling combined with probabilistic mechanics techniques are proposed for use during the actual system design-development phase to evaluate and optimize stress and wearout limitations of a design in order to foster the creation of highly reliable, robust E/E systems. A proposal for incorporating this approach into a future Revision H of MIL-HDBK-217 has been submitted to the DOD-DSPO where plans for implementing and funding this proposal are now being considered. This paper reviews the concepts on how PoF methods c- - an co-exist with empirical prediction techniques in MIL-HDBK-217. This is discussed from the point of view of a member of the MIL-HDBK-217 revision team. The author wishes to thank the leaders and team member on the 217 workgroup for their contributions.