Criticality rank is a value that provides an assessment of the failure mode’s severity and probability of occurrence. A failure mode with a rank of 1 is the most severe with the highest likelihood of occurring. The result is a categorized breakdown of failure modes based on risk as defined in the SAE ARP5580 FMEA standard. This type of analysis is called a FMECA (failure mode, effects, and criticality analysis).

The Severity and Occurrence fields are used to determine the criticality rank. When a failure mode has multiple effects with different severity classifications, the most severe is used to determine criticality rank. The result is stored in the Criticality Rank field in the FMEA Worksheet table.

The Criticality Rank field defaults to the mode level. However, you can modify the data level in the Project’s FMEA Design file. If the Severity and Occurrence fields are not defined in the FMEA Design file, criticality ranks are undefined. Because no results can then be calculated, the Criticality Rank field remains blank in the FMEA Worksheet table.