Thanks for your answers. I will try to describe the accident better.
An AS 350 BA (converted from "B") hauling loads with a 50ft rope in 3000ft PA, OAT 20°C, light and variable wind. Take off weight seems to be round about 1950-2100kg. (the load is destroyed and it's not possible to determine the weight of the load exactly) The >5000h experienced pilot lifted the load without problems and began to climb and to accelerate when suddenly the ship turns to the left. The left spin accelerated and wasn't to stop, even not with lowering the collective or full right pedal the pilot later explained. The ship and the load turned around the heads of the ground crew some full 360's and chrashed 50m ahead into the ground. The pilot doesn't opened the hook and released the load because he afraid to hurt someone on the ground.
As i wrote before there are no indications of a technical malfunction. The experienced ground crew reported the tail rotor was turning all the time. I' m surprised because the whole thing seems to me to be a kind of loss of directional control. That's not easy to understand because i thought LTE is a problem of the 206 or 500 series. Of course a loss of directional control is also possible on a AS350, but i have never heard about such a problem on AS 350 and never experienced personally on this type of helicopter. But i believe the pilot is really experienced on this kind of work, doing such flights a lot of years and will not loose the a/c out of control on such a "simple" flight during accelerating. But we are all humans and nothing is impossible.
Good to say the pilot isn't to bad injured and we all hope he will made a good and fast recovery.