On 29 April 2016, a CHC Helikopter Service Eurocopter EC225 Super Puma helicopter, carrying oil workers from the Gullfaks B platform in the North Sea, crashed near Turøy, a Norwegian coastal island 36 kilometres (22 mi) from the city of Bergen.

[3][4] The subsequent investigation concluded that a gear in the main rotor gearbox had failed due to a fatigue crack that had propagated under-surface, escaping detection.

Various safety recommendations were made, including for Airbus Helicopters, the current manufacturer of the type, to consider redesigning the affected gearbox.

It arrived at the Gullfaks B platform on time and departed at 11:16, carrying two pilots and eleven passengers, employees and subcontractors of Norwegian oil company Statoil.

Moments later the main rotor assembly of the helicopter detached, causing a sudden drop in speed and altitude, as confirmed by flight telemetry.

With all control lost, it crashed on the islet of Skitholmen between the islands of Turøy and Toftøy at 11:54:35 local time and exploded on impact.

[citation needed] Authorities confirmed that eleven of the people on board were Norwegian, with one British passenger and one Italian crew member.

[14] In May the BBC reported an earlier issue when the helicopter had returned to base in late April after the illumination of a cockpit warning light.

[15] In a press conference on 3 May, the AIBN stated that the initial investigation and analysis of data from the combined FDR and CVR convinced them that pilot error could be ruled out and that there were no indications of any malfunction until one second before the end of the recording, which they assumed was the moment when the rotor detached.

[18] Later that day Airbus Helicopters updated their press release bulletin with a request for verification of the correct installation of all main gearbox suspension bar attachments for the EC225LP.

[19] Within a week of the accident, an underwater sled with magnets had been developed and deployed to find small critical metal fragments from gearbox and bearings to support the investigations.

[20] On 27 May the AIBN confirmed that scenarios under consideration included failure of epicyclic module, suspension bar (lift strut) attachment and MGB (gearbox) conical housing.

[25] On 15 June, Airbus requested operators to check for metal residue in oil and to report unusual gearbox events.

[26] On 28 June the AIBN released a new preliminary report where they stated that the most likely cause for the accident was a fatigue fracture in one of the second stage planet gears.

In this report they stated that the accident was a result of a fatigue fracture in one of the eight second stage planet gears in the epicyclic module of the main rotor gearbox and that the crack initiation appeared to be a surface micro-pit.

[35] On 5 July 2018 the AIBN released the final report, they determined the cause as the following: The accident was a result of a fatigue fracture in a second stage planet gear in the epicyclic module of the main rotor gearbox.