Does not sound like engine to me....
Based upon the "reported" information....Sounds like a hydraulic failure, or some form of TR failure that got away from him.
About one minute prior to the accident, the radar indicated the helicopter climbed to 4,100 feet MSL and turned about 90 degrees to the left. The left turn and climb are not part of the normal route. Radar then indicated the helicopter descended to 3,300 feet MSL and tracked a northeasterly course for about 20 seconds, until entering a left turn then a descent.
Initial examination of the engine at the scene showed the engine was producing power at the time of the crash. All the servo-actuators, were removed from the wreckage on Friday and will be examined by the FAA and NTSB.