Better make that two blocked vents then because there is a NACA duct and flame arrestor on each wing. Plus of course the relief valves!
To be clear, if a scoop or flame arrestor becomes blocked, a pressure relief valve in the surge tank opens to make a vent.
There is a pressure relief valve in the inboard access door of each purge tank.
The pressure relief valve is normally closed. When it is closed, the valve is in line with the bottom of the wing. If a pressure difference opens the valve, it moves up as it opens. A spring holds the valve open until you close it. You have to pull a reset handle to move the valve back to the closed position.
When you do an inspection, you must look at the pressure relief valves to make sure they are closed. An open pressure relief valve is an indication of a blocked vent scoop or flame arrestor. The pressure relief valve can also open to relieve air or fuel pressure if there is too much pressure during refueling.
Sounds to me both the vent scoops/flame arrestors and pressure relief valve position are pre-flight/walk around items and should be snagged/corrected if any deviation from the normal was noticed.
Personally, while most issues focus on possible causes at subsystem level, i remain wondering if the cause to this accident should be viewed against the total scheme of things. Observing the aircraft as a whole with all systems interacting with each other. Why is no effort made to rebuild the original frame?
It is a unique opportunity with the aircraft relatively intact. Attach 2 serviceable engines (as far as the AAIB reports sofar engines are no suspect), re-attach the original gear, LRUs and wiring as much as feasible, put it on jacks and in the freezer, and do an air mode simulation with all systems operating and selected between TOD and moment of failure? Oh, and put the tail back on, the only reason i can figure why they took it off is either because it makes the frame sensitive to strong gusts or to remove the reference to the BA logo on it.
Who knows what such simulations may reveal?
Like i mentioned, just a personal thought.
Green-dot