This is what I was able to find, BH.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows.
a loss of control and the divergence of the main rotor blade system from its normal rotational path for undetermined reasons
Factual Report
Probable Cause
Peter R-B
In response to your question, I am unaware of any direct acceptance of liabality on the manufacturer's part, but, they have adapted their aircraft in response to common accidents/incidents on their types.
2 examples would be the addition of the throttle governor as a 'non-optional' piece of equipment, and the carb heat correlator on the R44s.