All Nippon Airways has announced a decision to ground five of its fleet of 11 Boeing 787 Dreamliners after a fault which causes corrosion was discovered in a gear box. However, since the decision was made, three of the jets have been allowed to take to the skies again while two remain on the ground waiting for spare parts.

The replacement engine parts are being supplied by UK manufacturer Rolls-Royce. The fresh problems with the Dreamliner saw Boeing’s shares drop by three percent. Shares in Rolls-Royce also lost three per cent following the grounding.

Boeing suffered a number of delays and testing problems which pushed back delivery of the first of its flagship aircraft. ANA was the first airline to fly a passenger service, but just weeks after it took delivery of the first Dreamliner it reported a problem with the landing gear.

According to person with knowledge of the situation the corrosion was discovered during an endurance test of a Rolls-Royce Trent 1000. The problem was discovered in a gearbox and linked by investigators to a manufacturing fault. The process has since been reversed.

In a statement ANA said that it had not seen the problem manifest itself in any of its 11 Dreamliners but that five currently carry the component and needed to be checked. The airline said other aircraft would replace the grounded planes and that it did not expect any passenger disruption.