Lu
Recovery from the low "G" roll is almost instantanious with application of aft cyclic. That is to say, that as soon as positive load is restored, the tail rotor no longer has authority over the main rotor and the right roll stops. Instantly. However, because the A/C is now banked to the right a little bit of left cyclic is needed to level it.I am speaking from personal experience and I think that this was probably what the instructor from the UK (previously mentioned) was trying to demonstrate.
Any left/right imput before positive "G" is restored will induce a mast bump and will not aid in recovery. I was also present when the incident as described by rotorque occured. The bottom of the mast fairing (on both sides) was bent up from contact with the cabin roof. The instructor,inexperienced on robbies, was not aware (at the time) of the low "G" problem nor the recovery and applied left cyclic with very little else. (that he could remember) The only reason it recovered, was as rotorque said, it went inverted and fell out of the sky. The instructor then instincively pulled back on the cyclic in order to pull out of the dive. Basically they did a half roll followed by a pull through and were very lucky to survive.
The POH page that you constantly refer to regarding out of balance flight states.
"Mast bumping may occur with a teetering rotor system when excessive main rotor flapping results from LOW "G" or ABRUPT CONTROL IMPUT. A low "G" flight condition can result from an ABRUPT CYCLIC PUSHOVER in fwd flight."
It also states that.
"High fwd airspeed, turbulence and excessive SIDESLIP can ACCENTUATE the adverse effects of THESE CONTROL MOVEMENTS."
It does not say anywhere, that sideslip or out of balance flight, alone, is responsable for main rotor flapping or mast bumping.
I hope this clears the air and puts every thing back in correct context.