What - FMECAs are a spreadsheet-type
approach to depicting the information about how failures manifest themselves in
system-level effects. The addition of criticality turns the FMEA approach into
a FMECA approach.
Why - FMECAs have been used extensively as a
system-level abstraction to quantify the existence of safety critical
behavior. FMECA's are a major contract item in reporting the failure
capabilities of a system.
When - FMECA's are typically developed early
through similarity analysis or as a conceptual view, and evolved later as a way
of reporting on failure mode models. When performed early and with a functional
approach, they are called FHA's or Functional Hazard Analysis. The FHA is used
as a baseline into which all future identified failure modes must fit, and
therefore fall within the original FHA scope.
Related Links -
Failure Mode Dependency Models, Fault Trees,
Reliability Block Diagrams