AIRBUS HELICOPTERS FINDS ROOT CAUSE OF THE TUROY H225 CRASH
On April 29, 2016, one H225 Super Puma helicopter operated by CHC Helicopter, en route from Gulfaks B to Bergen, went down near the small island of Turoy, west of Bergen, Norway. All 13 occupants of the heavy-twin, two pilots and eleven oilfield workers died in the accident after the main rotor separated from the aircraft at 2,000ft.
The loss of the main rotor in flight is the most dramatic accident that can happen to a helicopter. There are no words to describe it.
The UK magazine Flight Global reported that Airbus Helicopters has identified the root cause of the main gearbox (MGB) failure behind the fatal 2016 crash of an H225 in Norway.
In its final report in July 2018, Norwegian investigators determined that a second-stage planet gear in the MGB’s epicyclic module had failed due to sub-surface cracking and fracture of a bearing race. However, they were unable to say what had triggered the event.
“The investigation has shown that the combination of material properties, surface treatment, design, operational loading environment and debris gave rise to a failure mode which was not previously anticipated or assessed,” the report says.
But the airframer has continued its own analysis of the event, says H225 programme director Michel Macia, leading to identification of the root cause and a successful replication of the failure in testing. That work has been externally validated, he says.
Findings from that effort were subsequently shared with Norway’s SHT accident investigation body, regulators including the European Union Aviation Safety Agency, and other manufacturers, says Macia.
“Everyone now knows that the root cause is understood and has been reproduced,” says Macia.
Although he declines to detail the failure, he says the safety barriers put in place to enable the H225 to return to service deal with the underlying issue.
These measures include a heightened inspection regime, shorter life limits on components and – significantly – the exclusion of one of the two different bearing designs used on the helicopter.
The H225 and the related AS332 L2 were grounded for four months following the crash, and although both are now cleared for service, they have yet to be brought back to operation in the North Sea region for offshore transport.
While that is largely due to overcapacity in the sector, there remains significant opposition from the oil and gas workforce to the H225.
But Airbus Helicopters chief executive Bruno Even still believes the rotorcraft can make a comeback in the North Sea and says the aircraft needs time to achieve acceptance.
“We are doing all that we are able to do, but in the end, it is the customer who has to decide.”
The UK Civil Aviation Authority says its position on the H225 has not changed and it has yet to receive an application from an operator to resume H225 passenger flights in the country.
(Source: Flight Global – Image: Aibn/Super Puma rotor on Turoy Island)
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