Originally Posted by
GrayHorizonsHeli
not necessarily the ground.
I know it's a poor picture under magnification, but there's no dirt, grass or other ground debris embedded into the damage area.
it sustained enough damage that it was turning with sufficient inertia when it struck an object. One witness account i believe said the rotor wasn't turning, so if that is true, then the impact was early on in the incident.
Jesus wept, why are so many people trying to play amateur detective?
The ground it is on appears to be flat concrete, perhaps half derelict for a while, with pieces of broken concrete and some plant matter (such as might grow up through joints in old concrete) nearby.
But I'd distrust even that cursory look at one picture and it may turn out to be quite flat compacted soil.
Any impact can produce witness marks on both items, such as scratches in the rotor which may match scrapes on the other object, with paint fragments left on one or both objects.
I say again, leave it to the professional investigators, with access to far better evidence than a telephoto lens picture, video from a different day, fourth rate guesses based on third hand rumour of what some unidentified person may have said, miscellaneous other stuff.