The identification of all the probable ways that parts, assemblies, and the system may fail, the causes for each failure, and the effect that the failure will have on the capability for the system to perform its mission provides a valuable tool for systems engineers and design engineers. A failure modes, effects, and criticality analysis (FMECA) is a complete analysis of each level of the system. This analysis technique combines virtually all related engineering disciplines into a single activity. The key participants in development of the FMECA are listed at Figure 5-34. Using the FMECA, engineers identify each possible failure mode of the system. A failure mode is something that occurs, such as a part failing that causes the system not to function properly. A single part can have several failure modes. Something to be remembered when considering failure modes is that they are actual failures, not symptoms of failures. For example, if you put the key in the ignition of your car, turn it, and nothing happens, that is a failure symptom. The actual failure would be a dead battery, faulty ignition switch, etc. Turning the key and nothing happening is only an indication that a failure has occurred. The FMECA also provides information of failure indicators, or how users know when a failure has occurred.

Other information developed by a FMECA includes...