A very brief
statement on their website yesterday goes something like:
... The investigation so far has shown that the accident was the result of a fatigue fracture in one of the eight second stage planet gears in the main gear box, a failure with clear similarities with the crash off the coast of Scotland in 2009 with G-REDL. The fatigue crack developed without this being captured by the existing required or supplementary warning systems.
The investiagation is complex and with a broad scope. So far, the metallurgical studies has had the major focus. That is efforts to map and understand how the fatigue crack initiated and developed. This work is not yet completed.
Currently, the main focus of the AIBN investigation is the certification of the main gearbox and the robustness of the previous and current design requirements. This includes follow-up of safety recommendations given by the AAIB in connection with the accident with G-REDL and an assessment of the continuous follow-up of the gear box reliability. This work requires a close collaboration with the responsible parties, primarily the helicopter manufacturer and EASA.
The scope and complexity of the investigation means that it is not yet possible to estimate a date for when the final report is completed. The investigation continues with the same high activity. The Aviation Authorities in Norway and Europe are continually updated about the investigation.
AIBN intends to publish a new preliminary report on the 29 April 2017, unless significant new discoveries necessitates a preliminary report earlier.