Alouette:
The AS-350 hydraulic system (single actuator version) is pretty unique in the helicopter world. It's driven by a belt (which for the first 20 years of it's life failed with monotonous regularity), and has a very complex training procedure for simulating hydraulics off. It also has probably the most complex pre-takeoff checking procedure to make sure things are operating properly.
As far as other failures go, I've not heard of any other helicopter having hard-overs in the hydraulic system with the frequency that the AS-350 series has. I've had pilots personally report to me that they'd just turned the hydraulics back on and had the cyclic motor to the lateral stop and stay there for 30 seconds.
I could go on - a brief survey of service difficulty reports showed a huge number of servos removed for motoring or binding, and certainly not meeting time between overhaul.
My intention is suggesting that hydraulic actuators be looked at in detail is that at first glance there may appear to be nothing wrong by looking at the outside of the actuator - it's only in teardown that problems might be found.
I'm not pre-judging the cause of the accident, merely trying to make sure that a potential cause might be missed.