With reference to AirBoeing's post I have always thought the A330 Fuel Leak checklist to be a can of worms. It speaks of two scenarios - "Leak from Engine" or "Leak not from Engine or Leak not Located". It is very difficult to tell which applies and normally one will follow the second procedure initially which involves keeping the crossfeed CLOSED and turning all the fuel tank pumps off to allow gravity feeding at a lower altitude. There is a note however which says that if an engine flames out then one can assume that the leak is from an engine and apply that procedure which asks you to shut the engine down and turn all the fuel pumps back on. There is a note which says "The Xfeed valve can now be selected OPEN for rebalancing or to allow use of fuel from both wings".
The logic is that when the fuel pumps are turned off then air will be sucked into the engine through the leak if the leak is close to the engine and it will flame out. Shutting down the engine involves putting the Engine Master switch (Fuel switch) to off which closes the High and Low pressure fuel shutoff valves, therefore the leak should be isolated, allowing opening of the crossfeed. Of course if the leak is upstream of the Low pressure valve then all you are now doing is pumping the rest of your fuel overboard at high pressure.
This is all speculation of course and may have no bearing on this incident. And by the way, the 330 is a great glider with a huge wing and often the problem is getting it down.