Thank you, gentlemen. In reviewing the many posts I see several that claim lowering or bottoming the lever will stop the rotor rpm from decreasing. This is not true! This action does nothing more than reduce the rate at which the rotor rpm is falling. Period! It will continue to fall unless aft cyclic is applied in time to keep the rpm above the critical point.
Yes, with the rotor somewhere in the green, a turn during the descent will increase the rotor rpm, and this can be very handy when maneuvering to make a spot and will help keep the rotor rpm happy.
With the rotor rpm in the green, the helicopter can do any maneuver it can do with the engine(s) running except a sustained climb (from my initial post). As for picking a spot to land, I emphasize picking one that's too close. The pilot can handle too close, too high and too fast. Those are wonderful things to have. The opposites are not (too far away, etc.). And descending vertically works beautifully, especially if one has lots of altitude to get rid of. The high rate of descent is not a problem at all and the helicopter responds to all pedal and cyclic movements needed to keep the landing spot in full view of the pilot. A smooth forward movement of the cyclic quickly returns the descent to normal for the autorotation. I definitely prefer vertical descents to S turns or 360s. Keep the spot in view during the descent if at all possible. Ah, don't get me started on the mode of flight the helicopter prefers if given a choice... Think I'm kidding? Just ask your helicopter. It will answer that if you could fly all the time with the engine(s) not running, it would be wonderful!
My comments are directly aimed at the utility pilot doing field operations, not flying around the aerodrome or the practice area in a relatively sanitary training environment.
As for responding to falling rotor rpm in a twin, I think it is a huge mistake to do any troubleshooting before bringing the cyclic back and lowering the lever. Move the controls first, and THEN do the troubleshooting. The drive shaft failure in Twin-Pac powered machines is an example. Even if it is the failure of one engine, applying aft cyclic and lowering the lever a bit can help the remaining engine pick up the load.
It's time again for me to express my appreciation for the support of my efforts to make Cyclic Back a part of all training and publications everywhere.
Pete Gillies