Standard means of shedding ice from an iced-up fan is to apply a short, sharp application of power to the affected engine(s). The short increase in power, effectively, 'warps' the fan blade such that the ice is shed. This is particularly relevant during the approach phase when the engines are operating at lower thrust settings.
This would be the case if the engine anti-ice system had failed or had not been selected.
The RR Tay 620/650 engine is a good engine provided you look after it.