'Similar' helicopter fault reported
The gearbox failure that caused a helicopter to ditch in the North Sea with 19 people on board was a similar fault to that which forced the downing of another helicopter earlier this year, manufacturers said.
Eurocopter has advised more thorough and frequent monitoring of gearboxes on the EC225 Super Puma following the incident off Shetland on Monday.
The company said the failure of the vertical shaft was a "comparable" problem to that which affected a helicopter that ditched off Aberdeen in May.
A statement said: "Following the controlled ditching of an EC225, the investigation team along with Eurocopter and the operator have been able to perform an endoscopic inspection of the main gearbox which has identified the failure of the vertical shaft, comparable to the ditching of a Bond helicopter in May 2012.
"In co-ordination with AAIB (Air Accident Investigation Branch), BEA (the French body responsible for safety investigations into air incidents) and EASA (European Aviation Safety Agency), Eurocopter has implemented additional conservative measures to eliminate the risk of reoccurrence of another controlled water landing caused by the same failure. Those measures include an expansion of the scope of gearboxes monitoring and a reduction of the monitoring intervals."
An initial report by the AAIB revealed that a problem with the gearbox lubrication system caused the pilots to take action.
The Super Puma was carrying an oil crew from Aberdeen to a rig 86 miles (138km) north-west of Shetland when the pilot was forced to carry out a controlled ditching on Monday afternoon. The 17 passengers and two crew were rescued from life rafts by a passing vessel. No one was injured.
CHC Helicopter, the operator of the aircraft involved in the latest incident, has suspended all flights with the model. Two further operators, Bond and Bristow, have followed suit.
A spokesman for CHC said: "Representatives from across the industry will reconvene in meetings in Aberdeen to agree the terms and timing against which to return 'on hold' aircraft to service."
A Eurocopter statement said: "Eurocopter is devoting all of its efforts to fully understand the root cause of this failure, together with the authorities in charge of the investigation and will continue to maintain a strong information flow with the operators."