Failure mode and effects analysis
For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet.
It was developed by reliability engineers in the late 1950s to study problems that might arise from malfunctions of military systems.
Hence, FMEA may include information on causes of failure (deductive analysis) to reduce the possibility of occurrence by eliminating identified (root) causes.
The FME(C)A is a design tool used to systematically analyze postulated component failures and identify the resultant effects on system operations.
[3] Successful development of an FMEA requires that the analyst include all significant failure modes for each contributing element or part in the system.
In the extreme case, the FMECA would be of little value to the design decision process if the analysis is performed after the hardware is built.
While the FMECA identifies all part failure modes, its primary benefit is the early identification of all critical and catastrophic subsystem or system failure modes so they can be eliminated or minimized through design modification at the earliest point in the development effort; therefore, the FMECA should be performed at the system level as soon as preliminary design information is available and extended to the lower levels as the detail design progresses.
A typical set of ground rules (assumptions) follows:[4] Major benefits derived from a properly implemented FMECA effort are as follows: From the above list, early identifications of SFPS, input to the troubleshooting procedure and locating of performance monitoring / fault detection devices are probably the most important benefits of the FMECA.
[6] By the early 1960s, contractors for the U.S. National Aeronautics and Space Administration (NASA) were using variations of FMECA or FMEA under a variety of names.
[7][8] NASA programs using FMEA variants included Apollo, Viking, Voyager, Magellan, Galileo, and Skylab.
In 1971 NASA prepared a report for the U.S. Geological Survey recommending the use of FMEA in assessment of offshore petroleum exploration.
[13] A 1973 U.S. Environmental Protection Agency report described the application of FMEA to wastewater treatment plants.
[14] FMEA as application for HACCP on the Apollo Space Program moved into the food industry in general.
[16] The Ford Motor Company introduced FMEA to the automotive industry for safety and regulatory consideration after the Pinto affair.
[24] Although initially developed by the military, FMEA methodology is now extensively used in a variety of industries including semiconductor processing, food service, plastics, software, and healthcare.
This limits their applicability to provide a meaningful input to critical procedures such as virtual qualification, root cause analysis, accelerated test programs, and to remaining life assessment.
To overcome the shortcomings of FMEA and FMECA a failure modes, mechanisms and effect analysis (FMMEA) has often been used.
Following the release of IATF 16949:2016, an international quality standard that requires companies to have an organization-specific documented FMEA process, many original equipment manufacturers (OEMs) like Ford are updating their Customer Specific Requirements (CSR) to include the usage of specific FMEA software.
This can be done by analysis, calculations / FEM, looking at similar items or processes and the failure modes that have been documented for them in the past.
[30] This method allows a quantitative FTA to use the FMEA results to verify that undesired events meet acceptable levels of risk.
Indications to the operator should be described as follows: PERFORM DETECTION COVERAGE ANALYSIS FOR TEST PROCESSES AND MONITORING (From ARP4761 Standard): This type of analysis is useful to determine how effective various test processes are at the detection of latent and dormant faults.
The FMEA can be revised if necessary for those cases where this conservative assumption does not allow the top event probability requirements to be met.
[32][33][34] In the healthcare context, FMEA and other risk assessment methods, including SWIFT (Structured What If Technique) and retrospective approaches, have been found to have limited validity when used in isolation.
When used as a bottom-up tool FMEA can augment or complement FTA and identify many more causes and failure modes resulting in top-level symptoms.
Various solutions to this problems have been proposed, e.g., the use of fuzzy logic as an alternative to classic RPN model.
[36][37][38] In the new AIAG / VDA FMEA handbook (2019) the RPN approach was replaced by the AP (action priority).
The use of neural network techniques to cluster and visualise failure modes were suggested starting from 2010.
