Methods for Analyzing Severity Mitigation in FMEA

Severity-mitigating mechanisms (typically software-based) detect failures in a system and perform functions in order to reduce the severities of failures. Various approaches to FMEA analysis of severity-mitigating mechanisms exist within the industry. Three are compared and contrasted. Each method is compared against its ability to capture the three fundamental failures of a system that has severity-mitigating mechanisms:

1. 1
   a failure occurs and mitigating action is taken,
2. 2
   a failure occurs and mitigating action is not taken,
3. 3
   no failure occurs but mitigating action is taken.

One method is advocated over the others because it: uses existing FMEA formatting; addresses all three cases; supports consistent linkage between FMEAs in a hierarchy of systems with any number of layers.