One person close to the investigation, who was not permitted to speak to the media while the inquiry was under way, said Saturday that “some kind of explosion” might have occurred, because the floor above the cargo hold had been pushed up. Two oxygen bottles that supply the pilots are stored in that area.
Australian investigators, who got their first look inside the plane Saturday, discovered shards of an oxygen bottle throughout the cargo hold and in the floor above, which sits below the cabin, this person said. Officials cautioned that it was too soon to know if the oxygen canister had caused the damage, but theorized that it might have played a role, this person said.
The photos on post 358 clearly show a section of fuselage peeled out and up.
Assuming that the O2 tanks are approximately the size or diameter of SCUBA tanks (my assumption), it seems that the bottom part of a tank blew through the fuselage and then tore off the composite wing root fairing.
The weakest part of an O2 or compressed gas tank is at the valve fitting assuming no defect in manufacture.