Any thoughts from the aero guys about the incident that happened last week?

There are a number of oxygen cylinders in the hold, one exploded, parts of it came up through the cabin floor.  A fairing in front  of the wing came off, and some control systems were damaged.  No injuries.  Plane was enroute from Hong Kong to Melbourne, pilot made emergency landing in Manila.

Crew oxygen is stored in cylinders with lines going to the flight deck.  Standard procedures call for donning of the mask when one man of a two man crew leaves the flight deck.  Generators won't work for this applicaton.

It will be interesting to see if the cylinder losing the regulator caused the hole or if the cylinder lost it as it hit something else departing the airplane.  Rule #1 in these types of incidents is to never take what the media says as gospel.

747-400 has provision for up to 21 high pressure (1850psi/114cfm)passenger O2 system. Chemical system was considered, but the gaseous system won out, allowing more flexability for emergency descent.
The O2 bottles are located in the forward cargo bay and each are equipped with a frangible rupture disc (among other components such as gauge and SOV/Balance Valves).
The O2 system cylinders can be added or reduced depending on emergency descent profile for the route planned, saving weight.
O2 distribuion (free flowing, non free flowing and the capability to shut off O2 to areas where it is not needed) is per each customers requirement.
This system is very similar to previous 747's.

Hydrostatic requirements for high pressure cylinders is every 5 years hydro and internal inspection. I do not believe there is a fill/discharge cycle limit to these components.

It's very rare for a tank like this to rupture on its own if inspection intervals are being kept. Filling with other than O2 would most likely lead to an instant failure (explosion) and over filling would blow the disc. All the bottles are cascaded together, so the problem is in the one bottle that failed (assuming the SOV was open).

Mounting of the bottle, so that it was not secure and was damaged to the point of failure or a bottle that was dropped and had an inpending failure are the most likely reasons for failure...if the bottle failure is the sole excuse.
Something coming loose and damaging the bottle is another.

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