Structure Failure
In my 38 years as an engineer on Boeing, one thing we have learned is that cracks on structure that is hidden from view from normal inspection fail dramatically. Lap joints on Boeings are a major concern. This Qantas aircraft structure has failed at one such Lap joint, as is clear from the photograph. This area is hidden behind a fuselage fairing that gets opened once in 18 months. Cracks progress over rivet lines and in my aviation carrier I have seen hair line cracks as long as 24 inches and fuselage has not failed like in this incident. So this one must have remained out of sight for a long time. (Remember Aloha 737.)
One has to be patient for the experts to complete their assessment. Jumping to conclusions is amateurish. Some of the posts I have seen are hilarious to say the least.
1. Fuselage fairing failed first!!! It is clear that Fuselage skin popped out with an explosive force. A fiber glass fairing came in the way & it had no chance of holding on. So that was a secondary failure. It will be of ineterst here that when fully pressurised, fuselage skin 1ft x 1ft has a force of half a tonne on it. You can calculate the force on the skin on this failed area.
2. Oxygen bottle exploded!!! There will be a huge fire if that happens. There is no report of that in this case. Again oxygen bottles are not in this area.
The only possible human induced cause in this incident is an explosion of some sort or shifting cargo that made a small damage that resulted in a big failure when aircraft got pressurized fully at high altitude.