A helicopter which ditched in the North Sea last week while carrying 12 passengers and two crew members suffered a fault in its gearbox, an early report suggests.
Initial examination of the EC225 Super Puma which ditched 25 miles off the coast of Aberdeen on Thursday suggest it suffered a crack to a gearbox shaft, the Air Accidents Investigation Branch said.
Bond Offshore Helicopters, which operated the aircraft, suspended all EC225 flights after last week's crash while it investigates what happened.
The AAIB report into the latest crash says: “The crew of the helicopter carried out a controlled ditching following indications of a failure of the main gearbox (MGB) lubrication system and, subsequently, a warning indicating failure of the emergency lubrication system.
“The investigation has identified a 3600 circumferential crack in the bevel gear vertical shaft in the main gearbox, in the vicinity of a manufacturing weld, causing disengagement of the drive to both mechanical oil pumps.”
A gearbox failure was responsible the downing of a different model of Super Puma helicopter flying to Aberdeen from the Miller Platform in the North Sea in April 2009, causing the death of 14 offshore workers and two crewmen.
In a report in 2009 into the crash, the AAIB said the gearbox of the Eurocopter AS332L2 had suffered a “catastrophic failure” before it crashed into the sea.