The new SAE FMECA standard

Abstract

The new SAE FAMECA standard goes a long way toward bringing FMECA (failure mode effects and criticality analysis) into line with modern design practices. This is accomplished through three major changes. (1) The new standard describes the FMECA procedure as a process to be used throughout the product development cycle, rather than as a task to be done after the design is complete. It emphasizes the role of functional and interface FMECAs as well as that of the traditional piece part FMECA. (2) The concept of "failure mode equivalence" enables failure modes that have equivalent effects to be analyzed together and reduces much of the duplicative work generated by traditional component-by-component fault analyses. This concept allows the analyses of functional failure modes done early in the design process to be carried over to the effects of interface and piece-part failure modes analyzed later in the design. (3) Criticality is assessed using a Pareto ranking procedure based on the probability and the severity of the failure mode. This is more broadly applicable than the use of criticality numbers as defined in Mil-Std-1629 and it avoids some of the mathematical difficulties of the RPN analysis used in the Automobile FMECA standard, SAE J1739.