A-Floor, I know very little about 747s, but an FO I've flown with flew Connie Kallita Learjets for five years, and a guy who retired from Uncle Sam flew Kallita DC-8s just before he came here. It took all three crewmembers and a mechanic one night to convince Connie face-to-face that the elevator hydraulic pressure was inop; D. told me that the plane would never have rotated. If your Learjet engine flamed out at Connie, you descended and restarted it. If you declared an emergency-you were fired.
Of course the regulations are the same. Compliance and enforcement at some freight airlines, supporting the Captain's decisions, can be a totally different matter, and in the US this is not a secret among civilian pilots.
I also chatted a while at our layover hotel in Buffalo, New York with a gent who flew Tornados in either the German Marine or Luftwaffe. He then flew various smaller cargo jets and DC-6s on the East Coast (would not tell me the companys' names) before his present job. When a DC-6 engine caught fire, the crew never told the tower about it, even after tower asked about the excessive smoke/flames. They might have been terminated by their employer (?). Ask me if you want the phone numbers for the former Connie Learjet Captain (J) or the former DC-8 FO (D). I'll e-mail them to you.