We're in the middle of an AS9100 surveillance audit, and received a nonconformance for not always checking chemistry on material certs against specification. When we receive mill certs, we always check them against specification and PO to assure that we have the right material, and that it meets any special processing requirements (heat treat, spheroidizing, etc.). However, we do not always compare the lchemistry on the cert to specifications. AS9100 states that test reports must be acceptable per applicable specifications, and that the organization shall periodically validate test reports. We do periodic evaluation through independent labs. However, our auditor is telling us that in addition to that, to assure accuracey, every mill cert received must have chemical composition compared to the applicable specification for accuracy. In my opinion, this is his interpretation, not a black and white requirement. Just wondering if anyone out there has an opinion. Thanks.