Originally Posted by
ivorget
If I'm not very mistaken it can't possibly be a TR failure as many are suggesting because G-VSKP was clockwise-rotored (tail-rotor on right, unlike G-LCFC which appears in some pics) and the spiral down was in the direction of TR being the main force. So as others have mentioned issues such as TR hardover or main rotor vortex ring state are possible.
AW169 Main rotor spins in an anti clockwise rotation. Tail rotor in a clockwise. Aircraft spins in a clockwise rotation on the way down.
Vortex ring wouldn't cause that effect, it would just simply plummet.