Cracks in the wings of the world's largest passenger plane, the Airbus A380, stem from stresses caused by using unsuitable materials and the way engineers designed bolts to fit into certain brackets -- not stresses caused by flying, Airbus said.

The company, a unit of European Aeronautic Defence & Space Co., also said Wednesday all A380s now in service are being repaired.

Further, all superjumbos built in the future will have modified wing brackets that use suitable materials and bolts that reduce stress rather than increase it, reported the Wall Street Journal.

The problem emerged in November 2010 when one engine on an airborne Quantas A380 failed, ripping holes in a wing. Australian crews inspecting the damaged wing found cracks up to two inches long.

The cracks prompted the European Aviation Safety Agency to order mandatory inspections, requiring that one third of all A380 planes remain grounded until each plane has been inspected.

Since then, similar cracks -- some microscopic in size -- have also been found in A380s.