The Air Accidents Investigation Branch (AAIB) of the UK Department of Transport has issued Special Bulletin S6/2012 G-CHCN relating to the ditching of a CHC EC225 in the North Sea on Monday 22nd October.

The bulletin cites that an "...examination has identified a 360 degree circumferential crack on the bevel gear vertical shaft, in the vicinity of the weld that joins two sections of the shaft."

The bevel gear vertical shaft, common to EC225 and some AS332 L and L1 helicopters, is crucial to the operation of the main and standby lubrication systems for the main rotor gearbox. Failure of both systems can lead to catastrophic failure of the gearbox unless prompt action is taken by the crew. Evidently, prompt and correct action was taken, and all occupants evacuated from the helicopter, which has since been recovered.

This failure has wide ranging ramifications for the offshore industry and three EC225 operators have suspended operations using this type. EASA (European Aviation Safety Agency) and Eurocopter are reviewing the applicability and scope of Airworthiness Directive AD 2012-0115E, AS332 ASB No 01.00.82 and EC225 ASB No 04A009.

BBC News Article with video of recovery operation:
http://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-20076907