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Retest rquirements

Discussion in 'AS 91XX - Aerospace Quality Standards' started by Mikea7, May 8, 2024.

  1. Mikea7

    Mikea7 Member

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    Hello all,

    In the event that material fails a tennsile test and is retested at another lab and passes, is it required to disclose the initial failure?

    Thank you,

    Edit: Whoops, requirements
     
  2. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Mikea7 - welcome...

    A seemingly simple question, which AS 91XX standards don't specifically address, so a simple answer isn't possible. Indeed, it begs a number of follow-on questions such as who did the testing initially? An accredited lab? Then same for the subsequent lab? How much did the sample fail by? Was the second test sample homogenous with the failed sample? Etc...
     
  3. Mikea7

    Mikea7 Member

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    Hi Andy,

    I know, and I am quite perplexed at not being able to find the answer within the AS9100D standard or the testing standards that I have access to.

    To answer your questions:
    • Both tests performed by NADCAP accredited labs
    • the initial failure was close, but still out of spec
    • The second sample was taken from the same piece as the first sample
    Thank you for your help
     
  4. Andy Nichols

    Andy Nichols Moderator Staff Member

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    The next thought is about measurement uncertainty and if the results are affected by that. Do the labs both report similar confidence in their results?
     
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  5. Miner

    Miner Moderator Staff Member

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    Did the second sample marginally pass? If so, Andy is probably correct about it being a measurement uncertainty/R&R issue.
     
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  6. Andy Nichols

    Andy Nichols Moderator Staff Member

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    I'm unfamiliar with NADCAP lab accreditation vs ISO/IEC 17025 accreditation. One thought is regarding the scope of testing. They are the same or similar?
     
    Last edited: May 8, 2024
  7. Mikea7

    Mikea7 Member

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    The customer requires testing by either a NADCAP or ISO 17025 accredited lab, so I suppose they are roughly equivalent. The paseed test is within the low end of the spec range. I understand that reresting is acceptable, I am unsure if there is a requirement to disclose/include the the initial failure as well. to my mind, without a minimum of another test, it is impossible to determine if the material is actually nonconformant or if either lab has produced inaccurate results.
     
  8. Mikea7

    Mikea7 Member

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    Holy cow my typos! it looks like I'm typing with mittens on!
     
  9. Andy Nichols

    Andy Nichols Moderator Staff Member

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    Any testing is simply to provide results. What is important is what is done with those results. It could well be that the deviation from the standard isn't thought to be significant. It could be that the customer may accept the results. It can be handled under "control of non-conforming outputs" and there are a number of options available to you.

    It also occurs to me that the material provider would have tested it - is one of the labs theirs? Is that why one lab passed it and the other failed it? ;)
     
  10. Mikea7

    Mikea7 Member

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    The customer requires NADCAP or ISO 17025 testing. The material provider does not have either accreditation so that is why we sent a sample for external testing initially. The results on the test report from the material provider were at the edge of the low end of the spec. That makes the tally of results: 2 barely passing, 1 barely failing. This is the kind of thing that makes me unconfortable when boarding a plane.
     
  11. Andy Nichols

    Andy Nichols Moderator Staff Member

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    The provider doesn't necessarily need to be, but should be using an accredited lab - at their cost! Are they a distributor of materials? Do you have options to re-source the material from someone who has better control? It seems to me as if this is costing more than it should in unplanned costs, which is a good time to look at alternative suppliers...
     
  12. Mikea7

    Mikea7 Member

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    That is my take as well, though not for the same reasons. The cost of the testing relative to the profit on this order is negligible. My concern is delivering substandard material that is to be used in an aerospace application. I am in quality, not sales, so I don't get to make the calls on matters like this. In my experience, it is not uncommon for producers to not hold NADCAP, ISO17025, or AS9100 accreditation. Many are ISO9001. When we have situations where customers require NADCAP or ISO 17025 testing, we send to independent labs.

    I'm sure that like any material that is not unobtanium, it can be sourced elsewhere. whether or not it is at the same cost is probably why this is unfolding the way it is.
     
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