FMEA
- Failure Mode and Effect Analysis
The Failure Mode and Effect
Analysis (FMEA) is an Engineering Technique used to define, identify and eliminate
known and/or potential problems from a system. The FMEA is an ongoing process
that should start as a part of the first Design Review and continue throughout
the life of the product.
The failure mode is a function
of the part number. In general, each component part number in a system is analyzed
to determine its possible failure modes (open, short, mechanical failure etc.).
Every part has numerous potential failure modes and theoretically, there is
no limit as to the depth one could go. Practically, there is a point of diminishing
returns where the added cost exceeds the benefits derived. It is permissible
to combine similar failure modes if they have the same effect, they can always
be separated for finer resolution if necessary in the future. The initial FMEA
should include all of the system components that would be repaired or replaced
during a maintenance action. Additional components and failure modes should
be added as failures occur.
The effect of a part failure
depends upon the function of the part in the system. Two valves may have the
same part number but the effect of a failure will depend upon what the valve
is controlling. Therefore, it is very important that each system component be
assigned a unique symbol or designator that is completely independent from the
part number. The system schematic is the key document used to determine the
effect of a failure of a specific part, in a specific failure mode. The FMEA
considers each part and determines the effect that each failure mode will have
on the overall system.

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