Gearbox in Fatal Helicopter Crash Had Been in Road Accident

A preliminary report by air accident investigators said the most likely cause for the crash was a fatigue fracture in one of the second stage planet gears.

Iain Stuart, 41, from Laurencekirk in Aberdeenshire, was among those who died when the Super Puma went down near Bergen on April 29.

The helicopter crashed on the island of Turoey seconds after its rotor blades detached 2000ft in the air.

The investigators found the fracture grew in a manner which is unlikely to become detected by existing systems which would warn of an imminent failure.

A report from the Accident Investigation Board Norway (AIBN) said: “The AIBN finds it most likely that the fatigue fracture of this planet gear subsequently resulted in loss of the main rotor.”

The investigators are now trying to determine the origin of the fracture and how it grew.

The report continued: “The AIBN is aware that the gearbox was involved in a road accident in 2015.

“The gearbox was inspected, repaired and released for flight by the manufacturer before it was installed in LN-OJF in January 2016.

“Whether there is a link between this event and the initiation and growth of a fatigue fracture, is being investigated.”

There report said the fault showed similarities to another fatal helicopter crash in 2009 in the North Sea.

In that incident, 16 people died after the rotor blades of a Super Puma detached following a gearbox failure.

The report said: “Even though some differences are observed when comparing the LN-OJF accident with the G-REDL accident, the fatigue fractured planet gears, however, show clear similarities.”