Speed / Bank Limitations in Autorotation, including RRPM control
As the angle of bank is increased the load factor increases. In a 60° angle of bank the load factor is 2. The result of this is that either more power must be applied or the speed must be reduced to allow the vertical component of rotor thrust to remain equal to weight and prevent the aircraft from descending. At high AUM it may impossible to maintain altitude by application of power alone, although this is usually the method taught on the PPL course. Care must be taken when pulling power, as it is easy to exceed torque limits when trying to maintain a high angle of bank and altitude.
Any increase in disc loading, will cause a RRPM increase. Care must be taken when turning steeply not to exceed RRPM limits, usually by a slight reduction in throttle on ungoverned helicopters.
Effect of Wind In Turns At Low Level
Care must be exercised not to refer speed to ground references, which is more prevalent at low level, due to the close proximity of the ground and the higher apparent ground speed. Airspeed must be referenced to the airspeed indicator to avoid the risk of a high groundspeed low airspeed scenario developing as the helicopter is turned from into wind to downwind.
Wind will make the helicopter drift downwind and this may require a greater or lesser angle of bank dependant upon the desired ground track.
Care must also be exercised not to slip into the turn at low level as a ground collision may result.