Torque fluctuations
I spoke with a Test Pilot about this and his response was:
1. Quartering Tail wind causing large rudder inputs making variations in torque requirements upto 15-20%.
2. Coupled with a free turbine and a hydromechanical fuel delivery system based on torque requirements. The lag in demand and supply of fuel on such a varied torque requirement from the tail rotor causing the fuel system to go into resonance with the varying power demand. Like an undamped system in resonance the catalyst being the aircraft doing a pedal turn in quartering wind conditions.
I tend to agree, having seen other larger aircraft with free turbines easily tending to go into undamped oscillations of Free Turbine RPM with a little PIO of the collective even in straight and level flight. Maybe, these issues are catered for by more responsive FADEC based fule delivery systems, or by aircraft which do not have a propensity for tail rotor induced torque problems like the two bladed T/Rs like the Bell. I wonder what a Dauphin or a Fenestron based aircraft would behave in similar conditions. I believe, they are less prone to LTE and if I am not mistaken do not even have a torque gauge in the cockpit! Which is why they (Like the bumble bee) can hover in a 70 knot crosswind!