FMEA vs. FMECA: what changes when you add criticality
A failure mode and effects analysis (FMEA) is a structured way to list how an item fails, what those failures do, and what you might do about them. A failure mode, effects, and criticality analysis (FMECA) does the same work and then ranks the modes by some measure of criticality so the important ones are not lost in a long worksheet.
IEC 60812 is the current international reference for both. MIL-STD-1629A is the historic U.S. military FMECA standard. It has been cancelled, but many plants still recognize its language. Neither standard is a certification, and using a standard’s worksheet does not make a file “compliant” in any official sense.
Criticality can be a simple frequency × severity ranking, a risk priority number, or a more formal criticality number in the spirit of 1629A. What matters is that the ranking method is written down, that severity is defined, and that a high rank leads to an action or a conscious decision to accept the risk. A worksheet that never changes a PM or a spare is a filing exercise.
RCM uses failure modes too, but it insists on functions and consequences first. An equipment FMEA can feed an RCM analysis; it is not a substitute for one. See FMEA and FMECA consulting and the Failure Mode Library.