This document provides an introduction to Failure Mode and Effects Analysis (FMEA) and Failure Mode, Effects, and Criticality Analysis (FMECA). It defines what FMEA/FMECA are, discusses their importance and history of use. The document outlines the FMEA/FMECA process, including defining the system, identifying failure modes and effects, performing criticality analysis, and documenting results. It also covers FMEA/FMECA standards and guidelines and provides examples of different types that can be performed.
2. FMEA and FMECA
• What is it?
– A systematic analysis technique which
facilitates the identification of potential
problems by examining the effects of lower
level failure modes on system operation.
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3. Acronyms
• FMECA - Failure Mode, Effects, and
Criticality Analysis.
• FMEA - Failure Mode and Effects Analysis.
• CIL – Critical Items/Issues List
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4. Why is FMEA / FMECA Important?
• Provides a basis for identifying root failure causes
and developing effective corrective actions
• Identifies reliability/safety critical components
• Facilitates investigation of design alternatives at all
stages of the design
• Provides a foundation for
maintainability, safety, testability, and logistics
analyses
• FMECA and CIL (Critical Items List) evaluations
cross check the completeness of the safety hazard
analysis.
• Serves as a formal record of the analysis
performed. Could be used as evidence in court
(e.g. product safety).
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5. Background / History
• Originally part of risk management techniques
developed for defense and nuclear industries in the
1940’s.
• An offshoot of Military Procedure MIL-P-1629, titled
Procedures for Performing a Failure Mode, Effects
and Criticality Analysis, dated November 9, 1949.
• Used as a reliability evaluation technique to
determine the effect of system and equipment
failures. Failures were classified according to their
impact on mission success and
personnel/equipment safety.
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6. Background / History
• Formally developed and applied by NASA in the
1960’s to improve and verify reliability of space
program hardware.
• Early adopters were the
aerospace, petroleum, chemical, and automotive
industries.
• In the 1990’s the medical devices industry began
using FMECA in response to new FDA regulations /
guidelines.
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7. FMECA Standards/Guidelines
• The procedures called out in MIL-STD-1629A are
probably the most widely accepted methods
throughout the military and commercial industry.
• SAE J-1739 is a prevalent FMEA standard in the
automotive industry.
• SAE ARP5580 - FMECA for Non-Automotive
applications. Provides some upgrades to MIL-
STD-1629A.
• Army TM 5-698-4 – FMECA for C4ISR Facilities
• MIL-STD-882D – Helpful in assessing safety
issues and identifying critical items.
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8. Definitions
• Failure Cause: The physical or chemical
processes, design defects, quality defects, part
misapplication or other processes which are the basic
reason for failure or which can initiate the physical
process by which deterioration proceeds to failure.
Why does it fail? (Past)
• Failure Mode: The way in which a failure is
observed, describes the way the failure occurs, and
its impact on equipment operation. How does it fail?
(Present)
• Failure Effect: The consequence a failure mode has
upon the operation, function or status of a system or
equipment. What happens when it fails? (Future)
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9. Definitions
• Local Effect: The consequence a failure mode
has on the operation, function or status of the
specific item being analyzed.
• Next Higher Effect: The consequence a failure
mode has upon the operation, function, or
status at the next higher level of assembly.
• End Effect: The consequence a failure mode
has upon the operation, function, or status at
the highest level of indenture. Sometimes
referred to as a System Effect.
Types of Failure Effects:
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10. Definitions
• Severity: Considers the worst possible consequence
of a failure classified by the degree of injury, property
damage, system damage and mission loss that could
occur.
• Criticality: A relative measure of the consequences
of a failure mode and its frequency of occurrence.
• Failure Mode Ratio: The probability of occurrence of
a failure mode. The sum of the failure mode ratios for
an item should equal 1.0. Sometimes referred to as
alpha (α).
• Failure Effect Probability: Often referred to as the
End Effect Conditional Probability or beta (β).
Represents the probability that a particular failure
effect will result, given that a certain failure mode
occurs.
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11. Types of FMEA/FMECA
• There are many different flavors or types of
FMECA.
• Both qualitative and quantitative approaches may
be used.
• Some examples are:
Concept, Design, Process, Hardware, Functional,
Software, Interface, Healthcare, Machinery, Enviro
nmental, etc…
• The technique is basically the same when
completing each type of FMECA, but the criteria
used in determining failure
modes, effects, severity levels and other aspects
of the FMECA may be tailored for each specific
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12. Conceptual Validation
Engineering Development
Engineering Prototype
Production /
Deployment
Design
Process
FMECA
Design Reviews
ACQUISITION PROGRAM
Functional HardwareUpdates Updates
PDR CDR PRDR FACI
PDR - Preliminary Design Review
CDR - Critical Design Review
PRDR - Preproduction Design Review
FACI - First Article Configuration
Inspection
FMECA Timeline – Aerospace Industry
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13. • Design FMECA
– Start early in process. Complete by the time preliminary drawings are done, but
before any tooling is initiated.
• Process FMECA
– Start as soon as basic manufacturing methods have been discussed. Complete prior
to finalizing production plans and releasing for production
Concept Prototype
Build
Design Go-
Ahead
Production
Start
Eng./Mfg.
Sign Off
Design
Completion
Design FMEA Process FMEA
FMECA Timeline – Automotive Industry
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14. How is FMECA Done?
Bottom-Up Analysis Top-Down Analysis
Determine
failure modes
of lower level
items.
Work
upward
and
determine
effects.
Pick
upper
level
failure
modes.
Work
downward
and flow
down
causes.
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15. The FMECA Analysis Process
1. Define the system
2. Define ground rules and assumptions
3. Construct system block diagrams
4. Identify failure modes
5. Analyze failure effects / causes
6. Feed results back into design process
7. Classify failure effects by severity
8. Perform criticality calculations
9. Rank failure mode criticality
10. Determine critical items
11. Feed results back into design process
12. Identify means of failure detection, isolation and compensating provisions
13. Document the analysis. Summarize uncorrectable design areas, identify special
controls necessary to mitigate risk.
14. Make recommendations
15. Follow up on corrective action implementation / effectiveness
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