Failure modes, effects, and diagnostic analysis
Failure modes, effects, and diagnostic analysis (FMEDA) is a systematic analysis technique to obtain subsystem / product level failure rates, failure modes and diagnostic capability. The FMEDA technique considers: All components of a design, The functionality of each component, The failure modes of each component, The effect of each component failure mode on the product functionality, The ability of any automatic diagnostics to detect the failure, The design strength (de-rating, safety factors) and The operational profile (environmental stress factors). Given a component database calibrated with field failure data that is reasonably accurate, the method can predict product level failure rate and failure mode data for a given application. The predictions have been shown to be more accurate than field warranty return analysis or even typical field failure analysis given that these methods depend on reports that typically do not have sufficient detail information in failure records. The abstract of an FMEDA report typically mentions the Safe Failure Fraction (rate of failures that are neither dangerous nor undetected over the total rate) and the Diagnostic Coverage (rate of detected dangerous failures over the rate of all dangerous failures). Each term is defined equivalently in both standards, IEC 61508 and ISO 13849.