Bell 47G-2 N444EH accident near Flandreau, South Dakota

Probable cause

A malfunction of the helicopter’s throttle system, which resulted in a loss of engine power during cruise flight.

NTSB analysis

The pilot reported that the helicopter lost engine power during cruise flight. He initiated an autorotation; however, the only available landing area was a pasture that resulted in a tailwind approach and landing. The landing from the autorotation was reportedly a “little rough,” and the helicopter bounced and rolled onto its left side. A postaccident examination revealed that the throttle system did not operate properly. Specifically, the hand grip on the collective throttle control was loose and the throttle cable was not free to move within the conduit. The conduit did not appear to be deformed or damaged in a manner that would have prevented movement of the cable. The throttle conduit was replaced about 3 months before the accident; however, the existing throttle cable was reinstalled with the new conduit. A brief operational test of the throttle system was successfully conducted after that maintenance and the helicopter was subsequently operated for more than 25 hours without incident before the accident occurred.

Text from the NTSB. Open the NTSB docket for CEN12LA557 for the full record.