Also the
AAIB report on G-BZXE, with references to the fenestron stall and from 1518-67-01:
EUROCOPTER remind you that in some configurations (hover flight, flight at low speed in light wind etc), starting a turn to the left can induce a high-rate turn if the pilot does not apply quickly the suitable position to the yaw pedal. If the pilot attempts to counter this high-rate turn by applying the amount of right yaw pedal that corresponds only to hover flight control, this is not sufficient to start actual deceleration, thus allowing the pilot to regain his bearings.
In this situation, right yaw pedal, and if necessary, full right yaw pedal, must be applied quickly, and held, to stop the turn to the left. Any delay in complying with this procedure will increase the time necessary to slow the helicopter. This effect is NORMAL and must not give rise to doubts as to the performance of the tail rotor. In all cases, the helicopter will stop turning.
A reminder is also given that all turns to the left, in hover flight conditions or at slow speed, must be made applying moderate left rudder.