Page 117 - The Six Sigma Project Planner

Failure Mode and Effect Analysis (FMEA)
Failure mode and effect analysis (FMEA) is an attempt to delineate every possible
failure, its effects on the system, the likelihood of occurrence, and the probability that
the failure will go undetected. FMEA provides an excellent basis for classification of
characteristics, i.e., for identifying CTQs and other critical variables. As with Pareto
analysis, one objective of FMEA is to direct the available resources toward the most
promising opportunities. An extremely unlikely failure, even a failure with serious
consequences, may not be the best place to concentrate preventive efforts. FMEA can be
combined with decision analysis methods such as the analytic hierarchy process (AHP)
and quality function deployment (QFD) to help guide preventive action planning.

FMEA came into existence in the space program in the 1960s. Later it was incorporated
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into military standards, in particular Mil-Std-1629A. There are two primary approaches
for accomplishing an FMEA:
• The hardware approach, which lists individual hardware items and analyzes their
possible failure modes. This FMEA approach is sometimes used in product
Design for Six Sigma (DFSS) projects.

• The functional approach, which recognizes that every item is designed to perform a
number of functions that can be classified as outputs. The outputs are listed and
their failure modes analyzed. This approach to FMEA is most common on both
DMAIC and DMADV projects involving improvement of processes or complex
systems.

FMEA Process
The FMEA is an integral part of early design process and it should take place during the
Improve phase of DMAIC or the Design phase of DMADV. FMEAs are living
documents and they must be updated to reflect design changes, which makes them
useful in the Control or Verify phases as well. The analysis is used to assess high-risk
items and the activities under way to provide corrective actions. The FMEA is also used
to define special test considerations, quality inspection points, preventive maintenance
actions, operational constraints, useful life, and other pertinent information and
activities necessary to minimize failure risk. All recommended actions that result from
the FMEA must be evaluated and formally dispositioned by appropriate implemen-
tation or documented rationale for no action. The following steps are used in
performing an FMEA:
Define the system to be analyzed. Complete system definition includes identification of
internal and interface functions, expected performance at all system levels, system
restraints, and failure definitions. Functional narratives of the system should include

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Mil-Std-1629A actually calls the approach FMECA, which stands for Failure Mode, Effect, and Criticality
Analysis, but over time the “C” has been dropped from common usage. However, criticality analysis is
still very much a part of FMEA.

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