Key Characteristics - Critical vs. Major vs. Minor - AS9100 vs. MIL-STDs

[tkevmoore]

My company is transitiong to AS 9100 from our ISO system. Since we are a mil house, engineering and production are familiar with characteristics defined as critical, major and minor. With AS they need to be familiar with key characteristics. I've attached a document that pulls the mil definitions for critical/major/minor as well as the AS 9100 definition for key characteristic. It appears that key characteristics are the same as critical and majors except that they can apply to a process as well. If so can I just apply key characteristics to processes and say that material and part key characteristics are identified as critical and major?

 

[Sidney Vianna]

Re: Key characteristics vs critical/major

Don't forget that AS9100 Rev.C introduces a couple of new definitions:

3.2 Special requirements
Those requirements identified by the customer, or determined by the organization, which have high risks to being achieved, thus requiring their inclusion in the risk management process. Factors used in the determination of special requirements include product or process complexity, past experience and product or process maturity. Examples of special requirements include performance requirements imposed by the customer that are at the limit of the industry’s capability, or requirements determined by the organization to be at the limit of its technical or process capabilities.
3.3 Critical items
Those items (e.g., functions, parts, software, characteristics, processes) having significant effect on the product realization and use of the product; including safety, performance, form, fit, function, producibility, service life, etc.; that require specific actions to ensure they are adequately managed. Examples of critical items include safety critical items, fracture critical items, mission critical items, key characteristics, etc.

 

[tkevmoore]

Fortunately we are only pursuing Rev B at this point.

Need confirmation that my interpretation is OK. My Operations Director is tearing his hair out thinking that he has to go back and identify "key characteristics" for programs that may still be in production but whose designs haven't changed since the 70's. My interpretation is that we have identified the key characteristics just under a different name (critical characteristics, inspection points on control plans, process parameters, etc.) We've committed to using the term "key characteristics" in the future. But rather than spending a lot of non-value added time and energy revising old documentation can't I just link these concepts up to the term someplace like the QA Manual?

 

[Coury Ferguson]

<snip>We've committed to using the term "key characteristics" in the future. But rather than spending a lot of non-value added time and energy revising old documentation can't I just link these concepts up to the term someplace like the QA Manual?

If you are planning to make the changes in the future, then as far as I would identify "key characteristics" would be on new or revised drawings. I don't think that going back to the past is cost value added. Nor do I think that an Auditor from a CB or your Customer would require you to make changes to the past. Go forward not backward. This is my opinion.

 

[howste]

Fortunately we are only pursuing Rev B at this point.

If you're pursuing Rev B now, you'll be persuing Rev C within the next year or two. You may as well at least be aware now of what it requires so you don't have to make changes later...

Need confirmation that my interpretation is OK. My Operations Director is tearing his hair out thinking that he has to go back and identify "key characteristics" for programs that may still be in production but whose designs haven't changed since the 70's. My interpretation is that we have identified the key characteristics just under a different name (critical characteristics, inspection points on control plans, process parameters, etc.) We've committed to using the term "key characteristics" in the future. But rather than spending a lot of non-value added time and energy revising old documentation can't I just link these concepts up to the term someplace like the QA Manual?

You can call them whatever you like. If you've already been calling them one name, there's no need to change it all because you're looking at AS9100 certification. If you want to keep the name, that's fine.

If you still want to change future documents, explaining it in your quality manual or some other document would be fine.

 

[w_grunfeld]

Don't shoot me for bringing bad news
You are asking in fact two questions: 1. are Key Characteristics the same as critical /major in MIL-STS-916 and DOD-STD-2101 2. Supposing your interpretation is correct, do you have to go back and change in old designs.
Unfortonately, the answer to # 1, in my opinion is that they are not the same. Anything that is critical/major in the MIL's is a key characteristic, but de definition of Key Characteristic is much wider. Just one example to substantiate my reasoning: according to the AS9100 definition the diameter /tolerance of a pin that should fit in a hole is a key characteristic as variability of the diameter has a significant influence on the fit and manufacturability. It may not be critical nor major , yet it is a key characteristic according to AS9100, that needs special controls.
From this follows that your older designs may miss some charcteristics that are KEY although not critical nor major.
I am in the same boat as you, we are a subcontractor to a defense contractor that requires de-facto compliance to AS9100 , even though we are not AS9100 registered, it's a contract clause.
They look at the individual parts' drawings and demand that we identify at least one key charcateristic for every part.
Your Operations Director may not have to pull out all his hair, but quite a lot. It is true that usually no need to go back, but in your case if these old designs are still in production and the old blue prints only identify major/critical and not Key characteristics - your customer/auditor will likely claim that you will miss applying special controls to key characteristics that are not identified.