Originally Posted by englishal
...the negative G thing puts me off....but this is the same with helicopters like the R22 as well, so I don't know how much of an issue it really is.
I *believe* that 2 seater variants are pretty dangerous, something to do with the rotorheads???
All twin-bladed helicopters with teetering rotor heads have the same negative-G issue, including the Hueys, Jet-Rangers, R22, R44. In simple terms under low G there is a lack of upward main rotor thrust. This situation generates a roll to one side caused, amongst other things, by the tail rotor because the main rotor is no longer producing a lifting moment on the helicopter. If the instinctive reaction to push the cyclic left is followed, the unloaded rotor flaps excessively to the left but without load it doesn't move the aircraft. The blades can flap over 40 degrees over and the massive aerodynamic forces of the blades tilting the rotor mast bangs it against its 'bump stops' and will literally break the rotor right off the machine, and can chop off the front canopy or the tailboom as it does so.
The only way to survive the situation (which is outside the normal flight envelope) is to apply rear cyclic and raise collective to load the disc, *before* trying to correct the roll, which can be violent.
The 2 seater variants are not inherently dangerous, and (as far as I am aware) the Bell Jetranger, with the same rotorhead design, is one of the safest aircraft flying today.
There will be no way to determine what happened until an accident report comes out. My sympathies are with the families.
BW