"Part of the downside of the 206L "Nodamatic". It can be beating itself to bits with vibration and you won't feel it in the cabin.
Really evident if you fly an L for a while then get back in a B model."
The nodal beam is designed to only reduce fundamental main rotor 2/rev vibration and actually reduces loads in the airframe and on the xmsn/rotor side by allowing it to move in response to 2/rev rotor loads. It has no ability to mask any other vibration frequencies. Therefore, any abnormal vibration will be felt by the pilot just like in the 206.