According to CHC, the aircraft had flown from Aberdeen to two platforms in the North Sea before returning to Sumburgh.
Emergency services have recovered the four bodies and the wreckage of the aircraft, which was partly floating on the surface following the activation of the aircraft’s flotation gear. The fuselage has been loaded onto the oil and gas support ship, Bibby Polaris.
The accident is the second involving a CHC aircraft in less than a year. In October 2012, a CHC EC225 ditched into the North Sea. Although all onboard were rescued, the incident prompted the temporary grounding of the EC225 and military EC725 helicopters from operating over hostile environments such as open water, after the discovery of a failure in a main gearbox component. EC225s began returning to operations earlier this month after a series of interim fixes were approved by European regulators.
The last AS332L2 accident in the North Sea was in April 2009, when a catastrophic main gearbox failure onboard a Bond Offshore aircraft resulted in the deaths of all 16 people on board.