Also not every engineer is built equally. The guy making six figures leading the 300 engineer core would be the guy, or if you can talk to a senior test engineer. Furthermore if you walked a cessna guy into RV or someone and had him asking questions about their initial cert stuff (assuming the cessna engineer even delves into initial cert) his heart might have an attack when he finds out your not even doing industry best practices for bonding of materials because he came out of college and learned the cessna way (for instance). Usually the guys charging $4k a day as a third party would be your best source. Maybe one of the 100~ faa appointed DER would be a good start, but they cant tellyou how to do it except that youre doing it wrong. Old passed away Green or whatever his name was on this web board wrote an article once after interviewing a couple engineers at my old place of work and still didnt quite get it all to translate correctly and still won an award from someone doing something with biz aviation. He flew big military tin cans around in the 70s with no composite so theres some learning interference there.
Theres probably 60 to 80 guys with full balls to bones initial cert experience (experience but they arent completely knowledgable)in the usa. They are mostly employed through 3rd parties cessna pay big bucks to even talk to. Cessna for instance should still have billy Martin, not the coach, and he shepards every aircraft through conformity, somehow the cj1 and CitationX are the same thing. Most of those cessna guys couldnt tell you a waveform 3 from 5b, nm different antenna bs. If they can run a oscilloscope at x1000 for a inductive clamp probe ill eat my hat (pf course new ones can knock the signal down internally, but thats a good way to lose a box.) Ask billy about that gfs or gfx or gxs something (company name that does the windshields for cessna jets) he blasted to pieces in testing because he manhandled the probe up to the stupid metal frame. We all had a good laugh after the rep left, he felt so bad but he had such a good sense of humor and we all laughed with him.
Maybe 15 guys in the US can honestly give you correct and full answers and i worked with 8 or so of them. You didnt meet any.
That above is just me talking, im not trying to talk down to you, old jhugz and i had this out a while back. Its tough when you and i dont speak the same language. It aint because I think you're dumb or anything but its a deep dark world with lots of OJT and it's own language.