Saying all this does anyone remember some years ago an incident involving a freight 707 . In this instance the wing caught fire or someother such nasties. They manegd to land the thing in switzerland I think .The photos show that the netire skin of the wing had gone and spars ribs etc etc were all exposed , no smooth surfaces remaining , however the jet flew and landed without any injuries to the crew. Pilot mag did a big story on it , horrendous piccies but hell of an airmanship story cant find it on any website but well worth reading if your interested