I recall several years ago a story in the Seattle papers about a B-52 at McChord AFB. The crew had just flown in, and were walking away from the aircraft when its wing fell off. It just broke off at the root. There was even a picture in the paper -- it crushed a piece of ground support equipment.
Fatigue effects could explain this accident, too. The point is: there are plenty of plausible mechanical failure modes. "Air frame rattle" could indicate trouble at the wing root, and a wing failure, and the possibility of fuel and electrical sparks in close proximity, are consistent with the reports of flames at the "armpit" of the aircraft.
So the tail, AND both engine attachment points experienced fatigue failure simultaneously? - I don't think so...