At the risk of it appearing that I know somethihg about Skycranes, which I really do not.... It does appear to me that the photos of the poor machine lying upside down, show a tail rotor with very little damage. It certainly does not apear that it was turning when it hit the ground. Would stopping the main rotor as happened, also stop that tail rotor that quickly? Or could some other failure have caused it's stopping before the rollover was finished? Either way, it happened quickly!