North Sea operators have begun returning some Super Puma helicopters to work following the extension of EASA's emergency airworthiness directive for the type.
EASA issued to modified ruling on 25 October for the Eurocopter EC225 and AS332 following the latest ditching involving the type three days earlier. This was followed by a safety directive from the UK's Civil Aviation Authority which bans overwater flights using Super Pumas with affected bevel gear vertical shafts.
In addition, EASA mandates a number of checks that could prevent journeys to the furthest oil platforms supported by North Sea operators.
Bond Offshore Helicopters, whose EC225 ditched on 10 May following the failure of a key gearbox component, says it took a decision "in close co-operation with other helicopter operators, oil and gas customers, and Eurocopter", to return to service its two AS332L2s, which fall outside the scope of the directive.
However, its three EC225s and four other AS332 variants remain grounded.
"Bond Offshore Helicopters will not compromise safety and are working hard to assist its customers in finding creative solutions to help them during this challenging time for the industry."
The EAD now affects all EC225s and AS332s fitted with bevel gear vertical shafts, regardless of serial number. It reduces the time interval for helicopters operated over water for downloading and reviewing data recorded by the aircraft's Vibration Health Monitoring system. It also bans overwater flights by any of the type if they have no VHM system fitted, or an unserviceable VHM.
For the EC225 series this inspection/download interval is reduced to 3h operation, and for AS332s the interval is between 4.5h and 6h as specified, depending on the variant.
The reduction to 3h threatens the viability of the longest-range offshore support operations because of the time taken for the round trip.
EASA's move comes on the back of the 22 October ditching of an EC225 operated by CHC Scotia, and the earlier 10 May incident.
Eurocopter says it is working to "implement new solutions" in order to reduce the disruption caused by limited flight time on the EC225. "Eurocopter is devoting all of its efforts to fully understanding the root cause of this failure, together with the authorities in charge of the investigation and will continue to work closely with the operators," it says.