A long time ago and not in a 44, and with a very experienced instructor on board we decided to explore low RPM in the hover. At 60% it would be possible to get it off the ground but there was not enough left pedal to control yaw so we never lifted. The aircraft was flyable at about 75% but it could not be sustained as there was not enough power to maintain rpm. Almost full left pedal was required. At about 80% it was possible to sustain hover with difficulty. No, the grips did not hit the upper bump stops due to excessive coning.
This was difficult stuff and it doesn't surprise me a student 'playing' on his own came to grief.
The temptation to lift the lever a bit was perhaps too strong. Lift was there but not control.
Speculation of course.