The report was published today and the english summary goes like this:
As the helicopter started the descent for an approach in mountainous terrain, witnesses observed it turning tightly to the right. During the turn, control of the helicopter appeared to be lost, with a high bank angle and a steep descent. At the end, it seemed as if control was about to be regained, but the helicopter hit the ground hard about 500 metres short of the planned landing site and immediately caught fire. All five persons on board were fatally injured. The helicopter was a total loss.
The investigation has not revealed any technical defects or irregularities that could have influenced the course of events. The Accident Investigation Board Norway considers it likely that abrupt manoeuvring initiated a sequence where control of the helicopter was partly lost for a period, and that the height was insufficient for the commander to recover in time. The AIBN believes that the hydraulic system may have reached its limitation during the manoeuvring, resulting in the phenomenon servo transparency, (also called jack stall) occurring.
Three safety recommendations are issued in the report, dealing with limitations during manoeuvring with passengers on board, warning of servo transparency hazards and the need for flight recorders.
An english translation of the full report is availble here:
AIBN 2012/13 eng