The method involves identifying a necessary speed (NR) of a swing drive of a main rotor (1) by a control unit (10). The necessary speed is calculated by application of a calculation rule integrating a set of calculation parameters. Another calculation rule integrates a third calculation parameter with surplus power (S). The surplus power is related to requirement of power that is derived from a current power (Pc) of the drive at a current rotation speed (V), where the power requirement progresses towards anticipated power (Pf) of the drive at necessary speed.
