Talk:Failure mode, effects, and criticality analysis/Archives/2012

Merge with FMEA
should it be put inside FMEA? for me yes--212.147.90.65 13:54, 10 May 2007 (UTC)

yeap, should be only one article for FMEA and FMECA 87.234.26.2 13:40, 13 August 2007 (UTC)


 * I am a professional Reliability, Availability, Maintainability and Safety (RAMS) Engineer with 9 years of experience in the field of RAMS engineering both in Canada and the UK and I have extensive experience with the preparation of FMEAs and FMECAs. I agree that this should be part of the FMEA article and I believe that the text of this section can be improved to address varying international standards for performing FMEAs/FMECAs. Not all FMECAs will use RPNs, for example, and many FMECAs will address both safety criticality and operational criticality depending on the system being analyzed. The way I see it, the FMEA is only a first step and that the analysis isn't complete until the criticality has been assessed. I don't see much value-added from a stand-alone FMEA. The criticality portion of the analysis allows you to evaluate the cost-benefit of proposed failure management and mitigation. If a failure mode has a serious effect but will essentially never happen in the lifetime of the system, procedural or preventive maintenance mitigation is more likely to be chosen than a major design change. To get back to the original question though, in my opinion, there is no good reason for this to be a separate article. Radiantbutterfly 14:46, 15 October 2007 (UTC)

yes, it should be one article, inside FMEA

"The FMEA ist sometimes referred to as a FMECA, to underline the importance of the evaluation to determine the criticality of each identified "row"" should be fine. —Preceding unsigned comment added by 193.197.220.142 (talk) 09:25, 11 January 2010 (UTC)
 * I am doing my PHD on FMEA and I supported some enterprises using FMEA techniques. As far as I know, all of the FMEAs performed, include some form of evaluation, most based on the RPN. So all FMEAs already include the Criticality anlysis. The term that is used is FMEA (google Search results: FMEA >6.000.000; FMECA: <70.000). One short notice in the main-FMEA-article like

The FMEA article is not currently well organized to accept the FMECA topic. There are marked differences between the FMECA tradition of the military and space industries and the various FMEA traditions in civil aviation, automotive and health industries. It seemed to me simpler to revamp the FMECA article in the context of miltary and space. Rich Baldwin (talk) 03:05, 15 March 2010 (UTC)

RPN information in FMEA and FMECA
There is reference in both the FMEA and FMECA articles concerning RPN's.

The formula for RPN in the FMEA article states that: "...The overall risk of each failure would then be called Risk Priority Number (RPN) and the product of Severity (S), Occurrence (O), and Detection (D) but the Detection 1 means the control is absolutely certain to detect the problem and 10 means the control is certain not to detect the problem (or no control exists)...."

Whereas, the FMECA article states RPN as follows: "...The RPN is a result of a multiplication of delectability (D) x severity (S) x occurrence (O). Each on a scale from 0 to 10. The highest RPN is 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...."

While the math works out (from a multiplication standpoint), the definition of RPN and detectability is obscured since the equation is restated to identify criticality.

I think I understand what is intended, but to be clear to a layperson that might wish to read and understand RPN, this may seem somewhat ambiguous.

Maybe it's not, but it looks that way to me. —Preceding unsigned comment added by Pewtermug77 (talk • contribs) 00:15, 14 December 2007 (UTC)

Redefine "Detectability"
One sloppiness in the equation for RPN is the definition of the "D" factor.

The "D" stands for detectability, and can be defined as the likelihood of the failure not being detected by the design process before the product or system is used by the customer (see A few words about FMECA, http://www.johnstark.com/fwfme.html). A score of 1 could indicate that the failure will be found every time, and a score of 10 could indicate that the failure will not be detected before use by the customer.

Unfortunately, the factor's name contradicts its definition. A better name for it could have been undetectability, since it scores how undetectable a failure is.

However, to preserve the simplicity of the equation $$RPN = D x S x O$$, I propose that we describe "D" as the "difficulty to detect a failure," rather than the detectability of a failure.

I don't think that Wikipedia can replace the careless but widespread use of the word detectability in the FMECA litterature, but it would be a good place to at least complement it with a more accurate definition. jacques.boudreau, 206.104.31.47 (talk) 22:39, 15 January 2008 (UTC)

Untitled
This page is not really a stub as FMECA is a variation on FMEA. Most of the text on FMEA also applies to FMECA so it is not necessary to repeat it.

Tim 22:55, 7 February 2007 (UTC)