Please
Disregard my previous post. I mixed two different aspects (venting and gravity feeding). If venting is obstructed, then we can have structural damage. Nothing to do with gravity feeding. But now I have learnt what I am looking everytime I look at the cross in the wing lower surface during walk around (A320). That's why I love this forum.
By the way, in some airlines with A320 they note the time they pass FL 300 or start the chrono. In others they count the 30 min for the gravity feeding procedure after reaching any cruising level above FL300, but not after passing FL300 if still climbing.
Which do you think is correct?