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Do I need to test touchup of MIL-C-5541E Conversion Coating in my small shop?

Dear All,
I have a question regarding MIL-C-5541E Conversion Coating requirements of aluminum. Our shop fabricates metal assemblies for commercial aerospace vendors. We design and farm out aluminum sheet metal and machined components to local vendors. All of our systems are typically anodized per MIL-A-8625 Type I or IC, then primed and painted by our vendors. We perform ONLY final assembly via riveting or bolting the parts together. We do not perform any painting, anodizing or other finishing. When we ream holes prior to riveting, we typically conversion coat the holes with MIL-DTL-81706 solutions.

Do we need to perform testing per the MIL-C-5541E Process Control Inspections with test coupons, salt spray testing, etc., to say we meet those requirements? We do what I consider touch-up of fastener holes and an occasional scratch. I cannot find any level of requirements within that specification, or others, to see if they apply to what we do, and if we should be doing this.

Thanks much for your help in this matter.

Steve Sullivan
Manufacturing Engineer - St. Charles, Missouri, USA
February 7, 2011

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That's a tricky one, and not really addressed in Mil-DTL-5541F. But I would think that as long as your touch-up only covers up to 5% of the surface area per item as noted in the mil, the certification you receive from your processors should be acceptable.
But an approval from your customer probably would be a good idea.

Sincerely,

Micheline Forth
- Rincon, Georgia
February 11, 2011

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Hi Steve,

We had the same question although we use Mil-DTL-5541 (latest revision). You must qualify (periodic test) any solution according specification, regardless if it is a pen you use, a brush or a solution certified by the supplier. This was confirmed by our customer. A written approval from your customer not having to perform the tests is your only way out.

Best regards,
Jeroen

Jeroen Visser
landing gear - Geldrop, Netherlands
March 20, 2011