Preliminary Report  

Reading the report sounded like a chain of events.  The rotation described would be indicative of a loss of T/R thrust, however, the N2 deceleration would only be caused by catastrophic turbine failure or closing the throttle to stop the rotation.  In either case, the subsequent loss of rotor RPM would contribute to the high vertical descent rate.  As the investigation continues I’m sure more information will become available.  Regardless, their loss is felt not only in the community but industry wide.