80:
22:
281:
microcircuits, or valves. A piece-part FMECA requires far more effort, but provides the benefit of better estimates of probabilities of occurrence. However, Functional FMEAs can be performed much earlier, may help to better structure the complete risk assessment and provide other type of insight in mitigation options. The analyses are complementary.
1145:
RAC CRTA–FMECA and MIL–HDBK–338 both identify Risk
Priority Number (RPN) calculation as an alternate method to criticality analysis. The RPN is a result of a multiplication of detectability (D) x severity (S) x occurrence (O). With each on a scale from 1 to 10, the highest RPN is
485:
Severity classification is assigned for each failure mode of each unique item and entered on the FMECA matrix, based upon system level consequences. A small set of classifications, usually having 3 to 10 severity levels, is used. For example, When prepared using MIL–STD–1629A, failure or
292:
In this step, the major system to be analyzed is defined and partitioned into an indented hierarchy such as systems, subsystems or equipment, units or subassemblies, and piece-parts. Functional descriptions are created for the systems and allocated to the subsystems, covering all operational modes
214:
model, and by the 1980s FMEA was gaining broad use in the automotive industry. In Europe, the
International Electrotechnical Commission published IEC 812 (now IEC 60812) in 1985, addressing both FMEA and FMECA for general use. The British Standards Institute published BS 5760–5
191:. Possibly because MIL–P–1629 was replaced by MIL–STD–1629 (SHIPS) in 1974, development of FMECA is sometimes incorrectly attributed to NASA. At the same time as the space program developments, use of FMEA and FMECA was already spreading to civil aviation. In 1967 the
332:
Next, the systems and subsystems are depicted in functional block diagrams. Reliability block diagrams or fault trees are usually constructed at the same time. These diagrams are used to trace information flow at different levels of system hierarchy, identify critical paths and interfaces, and
1031:
represents the conditional probability that the failure effect will result in the identified severity classification, given that the failure mode occurs. It represents the analyst's best judgment as to the likelihood that the loss will occur. For graphical analysis, a criticality matrix may be
1010:
is usually fed into the FMECA from a failure rate prediction based on MIL–HDBK–217, PRISM, RIAC 217Plus, or a similar model. The failure mode ratio may be taken from a database source such as RAC FMD–97. For functional level FMECA, engineering judgment may be required to
1170:
Failure Modes, effects, and
Criticality Analysis is an excellent hazard analysis and risk assessment tool, but it suffers from other limitations. This alternative does not consider combined failures or typically include software and human interaction considerations. It also usually provides an
1094:
Once the criticality assessment is completed for each failure mode of each item, the FMECA matrix may be sorted by severity and qualitative probability level or quantitative criticality number. This enables the analysis to identify critical items and critical failure modes for which design
280:
FMECA may be performed at the functional or piece-part level. Functional FMECA considers the effects of failure at the functional block level, such as a power supply or an amplifier. Piece-part FMECA considers the effects of individual component failures, such as resistors, transistors,
218:
In 1980, MIL–STD–1629A replaced both MIL–STD–1629 and the 1977 aeronautical FMECA standard MIL–STD–2070. MIL–STD–1629A was canceled without replacement in 1998, but nonetheless remains in wide use for military and space applications today.
1103:
After performing FMECA, recommendations are made to design to reduce the consequences of critical failures. This may include selecting components with higher reliability, reducing the stress level at which a critical item operates, or adding redundancy or monitoring to the system.
143:
of failure modes against the severity of their consequences. The result highlights failure modes with relatively high probability and severity of consequences, allowing remedial effort to be directed where it will produce the greatest value. FMECA tends to be preferred over FMEA in
1146:
10x10x10 = 1000. This means that this failure is not detectable by inspection, very severe and the occurrence is almost sure. If the occurrence is very sparse, this would be 1 and the RPN would decrease to 100. So, criticality analysis enables to focus on the highest risks.
450:
Each function or piece-part is then listed in matrix form with one row for each failure mode. Because FMECA usually involves very large data sets, a unique identifier must be assigned to each item (function or piece-part), and to each failure mode of each item.
529:
Could result in permanent partial disability, injuries or occupational illness that may result in hospitalization of at least three personnel, loss exceeding $ 200K but less than $ 1M, or reversible environmental damage causing a violation of law or regulation.
541:
Could result in injury or occupational illness resulting in one or more lost work day(s), loss exceeding $ 10K but less than $ 200K, or mitigable environmental damage without violation of law or regulation where restoration activities can be accomplished.
459:
Failure effects are determined and entered for each row of the FMECA matrix, considering the criteria identified in the ground rules. Effects are separately described for the local, next higher, and end (system) levels. System level effects may include:
603:
Failure mode criticality assessment may be qualitative or quantitative. For qualitative assessment, a mishap probability code or number is assigned and entered on the matrix. For example, MIL–STD–882 uses five probability levels:
1136:
A FMECA report consists of system description, ground rules and assumptions, conclusions and recommendations, corrective actions to be tracked, and the attached FMECA matrix which may be in spreadsheet, worksheet, or database form.
1154:
Strengths of FMECA include its comprehensiveness, the systematic establishment of relationships between failure causes and effects, and its ability to point out individual failure modes for corrective action in design.
364:
For piece-part FMECA, failure mode data may be obtained from databases such as RAC FMD–91 or RAC FMD–97. These databases provide not only the failure modes, but also the failure mode ratios. For example:
1663:
1696:
Thoppil, Nikhil M.; Vasu, V.; Rao, C. S. P. (27 August 2019). "Failure Mode
Identification and Prioritization Using FMECA: A Study on Computer Numerical Control Lathe for Predictive Maintenance".
575:
For each component and failure mode, the ability of the system to detect and report the failure in question is analyzed. One of the following will be entered on each row of the FMECA matrix:
1158:
Weaknesses include the extensive labor required, the large number of trivial cases considered, and inability to deal with multiple-failure scenarios or unplanned cross-system effects such as
981:
907:
553:
Could result in injury or illness not resulting in a lost work day, loss exceeding $ 2K but less than $ 10K, or minimal environmental damage not violating law or regulation.
1116:, which both require data from the FMECA. FMECA is the most popular tool for failure and criticality analysis of systems for performance enhancement. In the present era of
1008:
789:
227:
Slight differences are found between the various FMECA standards. By RAC CRTA–FMECA, the FMECA analysis procedure typically consists of the following logical steps:
1672:
1124:
strategy for their mechanical systems. The FMECA is widely used for the failure mode identification and prioritization of mechanical systems and their subsystems for
811:
1029:
833:
1084:
1057:
758:
728:
700:
The failure mode may then be charted on a criticality matrix using severity code as one axis and probability level code as the other. For quantitative assessment,
341:
For each piece-part or each function covered by the analysis, a complete list of failure modes is developed. For functional FMECA, typical failure modes include:
855:
1596:
1509:
1474:
1543:
1386:
594:: the system erroneously indicates a safe condition in the event of malfunction, or alerts the crew to a malfunction that does not exist (false alarm)
1171:
optimistic estimate of reliability. Therefore, FMECA should be used in conjunction with other analytical tools when developing reliability estimates.
518:
Could result in death, permanent total disability, loss exceeding $ 1M, or irreversible severe environmental damage that violates law or regulation.
1288:
40:
487:
168:
1250:
301:
Before detailed analysis takes place, ground rules and assumptions are usually defined and agreed to. This might include, for example:
1547:
1461:
Reliability of
Systems, Equipment and Components Part 5: Guide to Failure Modes, Effects and Criticality Analysis (FMEA and FMECA)
1390:
98:
195:
released the first civil publication to address FMECA. The civil aviation industry now tends to use a combination of FMEA and
128:
284:
The criticality analysis may be quantitative or qualitative, depending on the availability of supporting part failure data.
477:
The failure effect categories used at various hierarchical levels are tailored by the analyst using engineering judgment.
1602:
1515:
1480:
1236:
171:(NASA) were using variations of FMECA under a variety of names. In 1966 NASA released its FMECA procedure for use on the
135:
analytical method which may be performed at either the functional or piece-part level. FMECA extends FMEA by including a
36:
270:
Document the analysis, summarize uncorrectable design areas, identify special controls necessary to reduce failure risk
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912:
863:
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93:
58:
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Analysis techniques for system reliability – Procedure for failure mode and effects analysis (FMEA)
986:
767:
1192:
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1125:
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is calculated for each item. The criticality numbers are computed using the following values:
796:
564:
1014:
818:
1776:
1062:
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706:
188:
167:, which published MIL–P–1629 in 1949. By the early 1960s, contractors for the
8:
196:
132:
1721:
1207:
840:
203:
instead of FMECA, though some helicopter manufacturers continue to use FMECA for civil
1725:
1713:
1421:
Design
Analysis Procedure For Failure Modes, Effects and Criticality Analysis (FMECA)
210:
Ford Motor
Company began using FMEA in the 1970s after problems experienced with its
192:
88:
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1705:
1335:
1301:
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1202:
180:
1671:. Federal Aviation Administration. 2005. AC 431.35–2A. Archived from
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184:
176:
172:
1765:
1717:
1395:. B. Reliability Analysis Center. p. 5. CRTA–FMECA. Archived from
1212:
1339:
1305:
1267:
1476:
Procedures for
Performing a Failure Mode, Effects and Criticaility Analysis
1368:. National Aeronautics and Space Administration JPL. PD–AD–1307
1117:
155:
applications, while various forms of FMEA predominate in other industries.
1165:
According to an FAA research report for commercial space transportation,
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1326:
1292:
1254:
1233:
Procedures for
Performing a Failure Mode Effects and Criticality Analysis
145:
140:
305:
Standardized mission profile with specific fixed duration mission phases
211:
204:
1542:
234:
Define ground rules and assumptions in order to help drive the design
1328:
Procedure for
Failure Mode, Effects and Criticality Analysis (FMECA)
1294:
State of the Art Reliability Estimate of Saturn V Propulsion Systems
588:: the system correctly indicates a malfunction requiring crew action
317:
Criteria to be considered (mission abort, safety, maintenance, etc.)
264:
Identify the means of failure detection, isolation and compensation
152:
1652:. D. European Space Agency. 1991. ECSS–Q–30–02A.
200:
691:
So unlikely, it can be assumed occurrence may not be experienced
1638:. National Aeronautics and Space Administration. SP–610S.
1442:. International Electrotechnical Commission. 1985. IEC 812
1385:
311:
Fault detection coverage that system built-in test will realize
175:. FMECA was subsequently used on other NASA programs including
1011:
assign failure mode ratio. The conditional probability number
1262:. Westinghouse Electric Corporation Astronuclear Laboratory.
582:: the system correctly indicates a safe condition to the crew
567:
space applications are derived from MIL–STD–882.
370:
Device Failure Modes and Failure Mode Ratios (FMD–91)
1665:
Reusable Launch and Reentry Vehicle System Safety Processes
1555:. Reliability Analysis Center. FMD–91. Archived from
1256:
Modes of Failure Analysis Summary for the Nerva B-2 Reactor
1197:
1112:
FMECA usually feeds into both Maintainability Analysis and
333:
identify the higher level effects of lower level failures.
276:
Follow up on corrective action implementation/effectiveness
149:
1463:. British Standards Institute. 1991. BS 5760–5.
1362:
Failure Modes, Effects, and Criticality Analysis (FMECA)
1650:
Failure Modes, Effects and Criticality Analysis (FMECA)
1334:. National Aeronautics and Space Administration. 1966.
240:
Identify failure modes (piece-part level or functional)
1392:
Failure Mode, Effects and Criticality Analysis (FMECA)
730:
is calculated for each failure mode of each item, and
1741:
Research and Development Accomplishments FY 2004
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1038:
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Unlikely but possible to occur in the life of an item
314:
Whether the analysis will be functional or piece-part
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Failure Probability Levels (MIL–STD–882)
495:
Mishap Severity Categories (MIL–STD–882)
163:FMECA was originally developed in the 1940s by the
31:
may be too technical for most readers to understand
1585:. Reliability Analysis Center. 1997. FMD–97.
1483:. 1980. MIL–HDBK–1629A. Archived from
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1002:
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680:Unlikely, but can reasonably be expected to occur
320:System for uniquely identifying parts or functions
169:U.S. National Aeronautics and Space Administration
1605:. 1998. MIL–HDBK–882D. Archived from
1518:. 1998. MIL–HDBK–338B. Archived from
1423:. Society for Automotive Engineers. 1967. ARP926.
1763:
1508:"7.8 Failure Mode and Effects Analysis (FMEA)".
976:{\displaystyle C_{r}=\sum _{n=1}^{N}(C_{m})_{n}}
902:{\displaystyle C_{m}=\lambda _{p}\alpha \beta t}
663:Likely to occur some time in the life of an item
486:mishap severity classification normally follows
1149:
649:Will occur several times in the life of an item
296:
1695:
357:Erroneous output (given the current condition)
336:
308:Sources for failure rate and failure mode data
635:Likely to occur often in the life of the item
114:Failure mode effects and criticality analysis
1546:; Denson, W.; Rossi, M.; Wanner, R. (1991).
1140:
1086:on one axis and severity code on the other.
570:
1107:
454:
87:It has been suggested that this article be
1698:Journal of Failure Analysis and Prevention
480:
71:Systematic technique for failure analysis
59:Learn how and when to remove this message
43:, without removing the technical details.
860:The criticality numbers are computed as
249:Classify the failure effects by severity
1747:. Federal Aviation Administration. 2004
1764:
1511:Electronic Reliability Design Handbook
598:
559:Current FMECA severity categories for
261:Feed results back into design process
246:Feed results back into design process
41:make it understandable to non-experts
1582:Failure Mode/Mechanism Distributions
1549:Failure Mode/Mechanism Distributions
1287:
1249:
1120:, the industries are implementing a
561:U.S. Federal Aviation Administration
287:
73:
15:
1598:Standard Practice for System Safety
1389:; Pemberton, S.; Rossi, M. (1993).
13:
1098:
360:Invalid output (for any condition)
14:
1798:
1632:NASA Systems Engineering Handbook
1342:. RA–006–013–1A
1183:Failure mode and effects analysis
327:
193:Society for Automotive Engineers
122:failure mode and effects analysis
94:Failure mode and effects analysis
694:Unlikely to occur, but possible
348:Failure to operate when required
267:Perform maintainability analysis
252:Perform criticality calculations
78:
20:
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1642:
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1239:. 1949. MIL–P–1629.
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1090:Critical item/failure mode list
237:Construct system block diagrams
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243:Analyze failure effects/causes
222:
215:in 1991 for the same purpose.
1:
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323:Severity category definitions
255:Rank failure mode criticality
139:, which is used to chart the
104:Proposed since December 2023.
1300:. General Electric Company.
1188:Integrated logistics support
1150:Advantages and disadvantages
1003:{\displaystyle \lambda _{p}}
784:{\displaystyle \lambda _{p}}
297:Ground rules and assumptions
7:
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337:Failure mode identification
10:
1803:
1710:10.1007/s11668-019-00717-8
1603:U.S. Department of Defense
1516:U.S. Department of Defense
1481:U.S. Department of Defense
1270:. WANL–TNR–042
1237:U.S. Department of Defense
1114:Logistics Support Analysis
158:
1141:Risk priority calculation
983:. The basic failure rate
666:Will occur several times
638:Continuously experienced
571:Failure detection methods
1308:. RM 63TMP–22
1108:Maintainability analysis
815:Conditional probability
702:modal criticality number
455:Failure effects analysis
258:Determine critical items
1782:Reliability engineering
1193:Reliability engineering
1095:mitigation is desired.
837:Mission phase duration
806:{\displaystyle \alpha }
732:item criticality number
488:MIL–STD–882
481:Severity classification
199:in accordance with SAE
1291:; et al. (1963).
1126:predictive maintenance
1122:predictive maintenance
1080:
1053:
1025:
1024:{\displaystyle \beta }
1004:
977:
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903:
851:
829:
828:{\displaystyle \beta }
807:
785:
754:
724:
652:Will occur frequently
1081:
1079:{\displaystyle C_{r}}
1054:
1052:{\displaystyle C_{m}}
1032:charted using either
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1005:
978:
929:
904:
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753:{\displaystyle C_{r}}
725:
723:{\displaystyle C_{m}}
565:European Space Agency
470:System status failure
418:Resistor, Composition
120:) is an extension of
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293:and mission phases.
273:Make recommendations
137:criticality analysis
793:Failure mode ratio
764:Basic failure rate
611:
599:Criticality ranking
497:
473:No immediate effect
372:
354:Intermittent output
197:Fault Tree Analysis
1787:Safety engineering
1208:Safety engineering
1076:
1049:
1021:
1000:
973:
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467:Degraded operation
368:
345:Untimely operation
1772:Impact assessment
1544:Chandler, Gregory
1387:Borgovini, Robert
850:{\displaystyle t}
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557:
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288:System definition
231:Define the system
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1704:(4): 1153–1157.
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464:System failure
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351:Loss of output
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173:Apollo program
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28:
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19:
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1678:on 2017-02-10
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1213:System safety
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29:This article
27:
18:
17:
1749:. Retrieved
1740:
1734:
1701:
1697:
1691:
1680:. Retrieved
1673:the original
1664:
1658:
1649:
1644:
1631:
1625:
1614:. Retrieved
1607:the original
1597:
1591:
1581:
1575:
1564:. Retrieved
1557:the original
1548:
1538:
1527:. Retrieved
1520:the original
1510:
1503:
1492:. Retrieved
1485:the original
1475:
1469:
1460:
1455:
1444:. Retrieved
1435:
1429:
1420:
1415:
1404:. Retrieved
1397:the original
1391:
1381:
1370:. Retrieved
1361:
1355:
1344:. Retrieved
1327:
1321:
1310:. Retrieved
1293:
1289:Dill, Robert
1283:
1272:. Retrieved
1255:
1245:
1232:
1227:
1169:
1164:
1157:
1153:
1144:
1135:
1132:FMECA report
1118:Industry 4.0
1111:
1102:
1093:
859:
731:
701:
699:
608:
602:
591:
585:
579:
574:
558:
515:Catastrophic
494:
484:
476:
458:
449:
379:Failure Mode
369:
363:
340:
331:
300:
291:
283:
279:
226:
217:
209:
165:U.S military
162:
136:
126:
117:
113:
112:
103:
92:
55:
46:
30:
1777:Maintenance
615:Description
504:Description
376:Device Type
223:Methodology
141:probability
1766:Categories
1751:2010-03-14
1682:2010-03-14
1616:2010-03-14
1566:2010-03-14
1529:2010-03-13
1494:2010-03-14
1446:2013-08-08
1406:2010-03-03
1372:2010-03-13
1346:2010-03-13
1312:2010-03-13
1274:2010-03-13
1251:Neal, R.A.
1219:References
685:Improbable
657:Occasional
550:Negligible
382:Ratio (α)
205:rotorcraft
127:FMEA is a
49:March 2022
1726:201750563
1718:1864-1245
1019:β
992:λ
931:∑
894:β
891:α
882:λ
823:β
801:α
773:λ
592:Incorrect
507:Criteria
133:inductive
129:bottom-up
1253:(1962).
1177:See also
643:Probable
629:Frequent
586:Abnormal
538:Marginal
526:Critical
501:Category
185:Magellan
153:military
124:(FMEA).
201:ARP4761
189:Galileo
181:Voyager
159:History
99:Discuss
35:Please
1724:
1716:
671:Remote
624:Fleet
580:Normal
187:, and
177:Viking
89:merged
1745:(PDF)
1722:S2CID
1676:(PDF)
1669:(PDF)
1636:(PDF)
1610:(pdf)
1601:. D.
1560:(pdf)
1553:(PDF)
1523:(pdf)
1514:. B.
1488:(pdf)
1479:. A.
1440:(PDF)
1400:(pdf)
1366:(PDF)
1332:(pdf)
1298:(pdf)
1260:(pdf)
618:Level
441:Short
410:Short
387:Relay
212:Pinto
146:space
118:FMECA
91:into
1714:ISSN
1198:RAMS
909:and
444:.03
434:.31
431:Open
424:.66
413:.19
403:.26
393:.55
150:NATO
148:and
1706:doi
1336:hdl
1302:hdl
1264:hdl
1059:or
535:III
97:. (
39:to
1768::
1720:.
1712:.
1702:19
1700:.
1235:.
1162:.
1128:.
547:IV
523:II
490:.
207:.
183:,
179:,
131:,
1754:.
1728:.
1708::
1685:.
1619:.
1569:.
1532:.
1497:.
1449:.
1409:.
1375:.
1349:.
1338::
1315:.
1304::
1277:.
1266::
1072:r
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1045:m
1041:C
996:p
969:n
965:)
959:m
955:C
951:(
946:N
941:1
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935:n
927:=
922:r
918:C
897:t
886:p
878:=
873:m
869:C
845:t
777:p
746:r
742:C
716:m
712:C
688:E
674:D
660:C
646:B
632:A
512:I
116:(
101:)
62:)
56:(
51:)
47:(
33:.
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