Eons ago I worked at Pratt & Whitney.

One of my projects was finding ways to identify counterfeit turbine blades that were causing issues for us on the PW2000 series engines.

It was sometimes super easy, other times they were the right dimensions, right alloy but improper manufacturing process and would have air cooling passage differences that short of destructive testing you'd never find.

Until they overheat locally and suffer a catastrophic creep failure.