Dinny,
The rib feet cracks were initially discovered when an inspection team found them repairing the Qantas A380 in Singapore.
This aforementioned A380 is testament to the structural integrity of the Airframe under a potentially catastrophic incident of the engine blowing itself to smithereens!
The cracked feet are only in a number of the Ribs inside the wing, the majority of which are not the material specification that is causing the problem.
The issue thankfully is an easily rectified production process change and is not a horrendous problem with the design of the wing causing unnecessary stresses.
IMHO from someone who certifies the A380, safe to fly and fly on.