I'm basing my suggestion on the Gazelle in which I have done OGE hovering and throttle chops but also the Sea King where we trained for forced landing from an OGE hover when we started a lot of FLIR searching.
In both cases, initiating with rapid down collective produced a nose down pitching and a reduction in g.
If this doesn't happen in Robinson aircraft then I'm surprised but happy to have my knowledge improved - not that I'll ever get in one of them again!
Crab, not saying that the RHC device doesn't respond to a lowering of collective by starting a descent, if you were powered, but if you had a power loss, then the matter is moot; there is no nicety in lowering the collective at all on the R-22, blade stall occurs by RHC's own analysis in 0.8 seconds, and my own recorded testing is consistent with that, where with an improved blade performance it is still a mind concentrating event. As the Nr collapses (this isn't the nice slow droop of the HH-3, this is more like a descent in a 269, the machine is on its way down, the choice is if you want to have tulip'd blades or want to still have a rotor system, and that requires a prompt lowering of the collective). John Anderson, once he regained his composure suggested that politely lowering the collective was undesirable to his health, that was my intro into whether there was any upper-speed limit in dropping the collective in an OGE hover loss of power.
The R-44 is much nicer to your health than the R-22, but the fundamentals remain the same, the loss of Nr is rapid and has to be responded to by prompt action. I would be more concerned with a case where the machine was not at a heavyweight, and in the power cut the student puts in the wrong pedal, more left instead of pressing right pedal (is USA) that will get a wild ride pretty promptly, and I would think it could compromise the TPP. As long as the rotor is still being driven in autorotation, the control system will function normally. A failure to lower the collective will definitely put the aircraft into zero-g quickly, as the rotor goes into the tulip until impact. As long as the collective is raised, the rotor will decelerate and the rate of deceleration is not trivial. RHC teaches failures every week at their school, and every RHC type trained pilot has experienced the same dynamics. OGE hovering is not for the slow of hand or unprepared driver. Personally, I avoid it whenever I can, happy to do all manner of torque turns, pedal stops etc, IGE failures, but OGE, ill keep the speed up unless there is a compelling reason to go well below ETL, and frankly, speeds above that give a great deal of recovery time as a cyclic loading of the disk trades off speed to Nr. Extremely high speed autorotations are another matter again, there you dont want to "dump a collective" on a robbie, just like you dont on a UH1, that will wind the blades up off the top of the tacho, and gets expensive, that ends up being a gearbox, head and rotor change out. The high speed entry also gives a considerable nose tuck, at the same time as the disk starts to flap back until autorotation is established, (now, that is a bit of maths worth looking at). I tested to 111% VMO at what was supposed to be 90% Nr, but ended up going a little beyond the speed and a little below the Nr. The system once established in autorotation will vibrate considerably in that case, but fly it does. Turning adds vibration depending on the direction of turn. About the only interesting thing in that was while measuring the torsion and bending loads on the rotor blades, and the pitch link strains, found that the entry into autorotation produces momentary loads on the blades and the pitch links that are only matched in the system at one other time, and that is as you touch down. No matter how softly the touchdown is, it is detectable as a load into the disk, which I found interesting. those loads were much more interesting than the steady-state, pitching or rolling loads in the system. That was done on my flight test program, not RHC, but the data says what it says. That was also for clarity, under Part 21 experimental category, with a parachute. Now, the good news is, when you want to work out how to bail out of a RHC, the removal of the blades has an obvious method, doesn't need explosive bolts, just a handful of collective and a twist of the throttle. Do recommend having a parachute on for that though.
Yes, the nose drops, but the TPP follows the control plane, unless there is a big input of cyclic. The thing that concerns me is someone hitting left pedal on entry while in a state of increased anxiety, which may well compromise the TPP/tail boom. A yaw rate from the wrong pedal can lead to the feedback through the control plane and result in an awkward motion of the rotor while the body is rotating underneath the mast, with an offset of the CG to the mast.
All of the above probably goes into the realm of Wayne Johnson to do the maths, or Gordon Leishman, or may be a topic for Shawn Coyle to comment on. Ray Prouty would have given a solution in short order too in small sentences.
Good news though, I'm done with PPrune, you guys fly safely and keep the blue on the top and the needles in the green.
Cheers,