Michinyon, you are incorrect on a couple of counts.
Corrosion is a common problem with aircraft, and if not identified and managed properly, can have serious consequences. The best example I can think of was the Aloha 737 that lost a third of the top half of its fuselage. Constant exposure to the salty sea air environment was the cause, and it obviously wasn't picked up through inspections.
Early 747s were the subject of one of the largest rectification programs in commercial aviation when structural fatigue was found in part of the aircraft called Section 41. This was a design weakness, as no particular issues were expected in that part of the fuselage.
Scary how close this explosion would have been to the centre fuel tank, although since TWA 800 I believe all 747s fly with a fair amount of fuel in that tank, even on short flights, to avoid a build up of explosive fuel vapour in the tank.
