Airbus has traced the problem to the 7449 aluminium used in the wing ribs. 7449 is more sensitive to the way the parts are assembled on the wing. They ruled out flight loads or fatigue as causes.
My 2 cents.
The rib feet cracking is in both carbon and alloy ribs.
The cracking has been found across the fleet (all airlines)
Some cracking has been found on wings not yet fitted.
The root cause seems to be in manufacture.
The fit of the fastener (similar to pictured in Turbine D post) has to much negative tolerance in the fit and therefore induces the cracks some of which can be seen by the naked eye others are found by NDI.
The inspection /repair sched is for the C2 check which will probably add many extra days to the ground time
This info is not knew and I am suprised it has taken this long to hit the prune
