A preliminary investigation report of the CHC-operated Super Puma helicopter crash in Norway has found that the accident most likely was a result of a fatigue fracture.
To remind, the helicopter accident, in which 13 people died, happened on April 29 near Bergen, offshore Norway.
The Accident Investigation Board Norway (AIBN) issued its fourth preliminary report on June 28 in order to disseminate findings from the ongoing investigation into the accident. Previous reports have been issued on May 13, May 27, and June 1, 2016.
At this stage of the investigation, the AIBN finds that the accident most likely was a result of a fatigue fracture in one of the eight second stage planet gears.
According to the AIBN, it appears that the fracture has propagated in a manner which is unlikely to become detected by existing mandatory or supplementary systems for warning of an imminent failure. What initiated the fracture has not yet been determined, the AIBN said.
An important issue will be to seek to determine the origin of the fatigue fracture and the mechanisms behind its growth. The AIBN said it is aware that the gearbox was involved in a road accident during transport in 2015 after which it was inspected, repaired and released for flight by the manufacturer before it was installed.
“Whether there is a link between this event and the initiation and growth of a fatigue fracture, is being investigated,” the investigation board concluded.