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Overview RelCalc V5.5-217F2 includes a calculation option to use the VITA 51.1 Improved Quality Factors for more realistic MTBF results. This is especially useful when calculating using MIL-HDBK-217F-2 environments other than GB. Background The MIL-HDBK-217F-2 models have not been updated in over 25 years, due to DoD politics and various other issues. Back in 2008 a group of people representing the government (Naval Surface Warfare Center, Defense Supply Center) and some of the largest military contractors (Boeing, Curtiss-Wright Controls, General Dynamics, Raytheon, Northrop Grumman, Honeywell Aerospace, etc) developed a spec, ANSI/VITA 51.1, to address the aging MIL-HDBK-217F-2 models. This is from the Introduction of the current version of that spec (ANSI/VITA 51.1-2013 (S2025), May 7, 2025)... ---------------------------------------------------------------------------------------------------------------------------------------------------- Reliability engineers in government and industry continue to use MIL-HDBK-217F Notice 2 to perform failure rate predictions. Because it has not been updated recently, there are many new developments in electronics that are not accounted for, so reliability engineers must make changes to the MIL-HDBK-217F Notice 2 methodology to make their failure rate predictions more realistic. This specification provides a standard method of performing reliability predictions on COTS modules using MIL-HDBK-217F Notice 2. This is not a revision or a modification of MIL-HDBK-217F Notice 2 but a standardization of the inputs to the MIL-HDBK-217F Notice 2 calculations to give more consistent MTBF numbers. This specification will assist the user in determining the credibility of published failure rate information and outline the techniques necessary for developing and applying this information to military or high reliability applications. ---------------------------------------------------------------------------------------------------------------------------------------------------- We've been using the VITA 51.1 Improved Quality Factors for MIL-HDBK-217F2 consulting jobs for years. We have also suggested using the VITA 51.1 Improved Quality Factors to many of our RelCalc V5.1-217F2 customers. Until now, we had to do this with a somewhat laborious manual process using the RelCalc What-If? function to batch change Quality Levels for various part types (Resistor, Capacitor, etc), one part type at a time. Now, with this new feature in V5.5-217F2, it's quick and easy to set this calculation option with the "Use VITA 51.1 Improved Quality Factors" checkbox in the Calculate dialog box. Notes - This is based on the current VITA 51.1 document: ANSI/VITA 51.1-2013 (S2025), May 7, 2025. - T-Cubed Systems, Inc. has permission from VITA to use the VITA 51.1 Improved Quality Factors. - IMPORTANT NOTE: T-Cubed Systems, Inc. has no connection or affiliation with VITA, and VITA does not review, approve, endorse, or support the RelCalc software in any way. - You can buy the document here (note: you don't need it): https://www.vita.com/Standards Search this page for the item: ANSI/VITA 51.1-2013 (S2025). |
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