PFMEA RPN rankings - Preventative action must be opened if RPN over 100

C

ckusnierek

#1
Hi everyone I have been working on establishing Risk Management procedures and have had a great deal of advice (this thread)

I think I have a good handle on everything at this point but was looking for some more information regarding a PFEMA's RPN.

Should I create a standard that says something to the effect "If a RPN is greater than 100 and Preventative action must be opened"?

Or do standard rankings already exist?

Thanks
Chris
 
Elsmar Forum Sponsor
#2
Re: RPN rankings...

Hi Chris.

I would advise against it. Only because I do not like artificial walls. The RPN gives us a way to prioritize our risks, but we should maintain the flexibility to attack those problems that are important to us. You might have an extremely low RPN number that is also low hanging fruit (easily fixed), so you might want to deal with it regardless of the RPN. Likewise, you might have a higher number RPN with a rating of 1 or 2 for Occurrence, and decide to hold off on that because it probably won’t occur.
I think each PFMEA action should be determined based on its own merits, not based on some arbitrary number.
 
C

ckusnierek

#3
Re: RPN rankings...

Yeah I kinda figured that out after posing this.
Deal with them on order of priority....
 
J

Joyrider6482

#4
Re: RPN rankings...

Just a thought - there appears to be an unwritten standard or rule of thumb suggesting an RPN threshold at 100. In my opinion it it best to address it head-on in your documented process. I have chosen to do a couple of things. First, I use Excel copies of the AIAG format and have set up red, yellow, and green color codes for Severity, Occurence, Detection, and RPN values. My system is intuitive in that a Red color codes demand action, yellows demand evaluation, and green require nothing further. I do use the 100 threshould for RPN as my introductory "red", But I also have severities of 9 or 10 as red, for example.
 

Jim Wynne

Staff member
Admin
#5
Re: RPN rankings...

Just a thought - there appears to be an unwritten standard or rule of thumb suggesting an RPN threshold at 100. In my opinion it it best to address it head-on in your documented process. I have chosen to do a couple of things. First, I use Excel copies of the AIAG format and have set up red, yellow, and green color codes for Severity, Occurence, Detection, and RPN values. My system is intuitive in that a Red color codes demand action, yellows demand evaluation, and green require nothing further. I do use the 100 threshould for RPN as my introductory "red", But I also have severities of 9 or 10 as red, for example.
One of the changes in the most recent AIAG PFMEA manual (which might not apply here, as the post is in the 13485 forum) was the advice that setting threshold or "trigger" limits is a bad idea, and I agree. It's far too easy to manipulate the numbers such that an RPN of say, 120, magically becomes 96 and work is avoided. Action should be taken in all cases where improvement is realistically possible, and actions should be taken in order of potential risk. Note that one fallacy regarding improvements coming out of the FMEA process is that they must always be done sequentially; in real life they can often be done concurrently. The idea though, is that when you must choose what to do first, that the relative amount of risk involved be taken into account.
 

Miner

Forum Moderator
Staff member
Admin
#6
Re: RPN rankings...

I think they also recommended the following in the FMEA manual:

  • Focus on Severity first (e.g., 9 and 10)
  • Second, focus on high criticality scores (Sev x Occ)
  • Last, focus on the highest RPN scores on a continual improvement basis, not on an arbitrary threshold value.
 

Marcelo

Inactive Registered Visitor
#7
And, as always, i´d like to warn on getting too involved and dependent on the "risk analysis technique" (that´s what an FMEA whould be, on the ISO 14971 framework - a part of the risk analysis) and forget about the "risk management process/system" objective - make all risks related to the devices (including related proccesses) acceptable.

This is something that happens a lot.
 
J

jscholen

#9
I recognize that I'm in the ISO13485 forum, but I'm assuming you will be marketing in the USA. I'm going to respectfully disagree with the responses in regards to not having action tables. There are allot of great points in the responses to your original posts as to specifics so I'm not discounting most of the 'How to's'...

I say you should have a table with Action Triggers. Even Medtronic has a scale with actionable triggers. You have to direct your people with almost precise instruction.

It's far too easy to manipulate the numbers such that an RPN of say, 120, magically becomes 96 and work is avoided.
The problem with not having the action triggers is that nothing could get done either.

FDA is focused on what is being done and how those actions are being triggered. If you don't have a triggering action, then you could potentially see something get missed.

That being said, if you do have high RPN values and can take no further action, there is nothing to say that you can't justify continued marketing of your device...its called the Risk Benefit analysis per ISO 14971. You just need to provide adequate instruction on allowing this type of justification and be sure Senior management is in agreement.
 
A

adamsjm

#10
As for RPN, RPN is a misnomer. Risk is derived from the Severity-Occurrence matrix as stated in the FMEA rev.4 manual. RPN should only be used to compare the before and after recommended action RPN values. It gives you a relative improvement value of the recommended action. Such as, we have reduced the risk of this failure mode cause by 38%. DO NOT rank causal / failure mode risk by RPN.
 

Attachments

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