There was an extensive thread on the Rotorheads forum about this crash with everything from LTE to vortex ring to engine failures suggested as the cause. A recent American visitor to our flight (and a blackhawk operator) was of the opinion that they just ran out of power and failed to execute a flyaway before hitting the mountain - apparently the latest models of Blackhawk are very powerful, even at 11000 ft but the one that crashed was an older and heavier model.