NTSB Factual Report

On August 14, 2012, about 0910 central daylight time, a Bell model 47G-2 helicopter, N444EH, was substantially damaged during an autorotation following a loss of engine power near Flandreau, South Dakota. The pilot and passenger were not injured. The aircraft was registered to and operated by private individuals under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The flight originated from Flandreau Municipal Airport (4P3) about 0815. The intended destination was the pilot's farm located near Colman, South Dakota.

The pilot reported that after conducting three approaches to the runway at 4P3, he departed for his farm. He stated that during cruise flight, about 4 miles from the farm, the helicopter lost engine power. 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,” causing the helicopter to bounce and roll onto its left side. The tail boom, main rotor blades, tail rotor blades, and fuselage were damaged during the autorotation landing.

A postaccident examination conducted by a Federal Aviation Administration (FAA) inspector revealed that the throttle system did not operate properly. At the time of the examination, the hand grip on the collective throttle control was loose. Movement of the hand grip did not fully translate into movement of the throttle linkage. The throttle cable was subsequently disconnected at both ends and further examination revealed that the 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.

A review of maintenance records revealed that the most recent annual inspection was completed on March 12, 2012, at a total airframe time of 15,659.1 hours. At the time of that inspection, the engine had accumulated 549.0 hours since overhaul. The records included an entry dated May 8, 2012, which stated, “New throttle conduit and cable installed. Needs Test.”

The mechanic that performed the maintenance on the throttle system stated that he had replaced the conduit but had used the same cable assembly. He noted that the conduit was in new packaging from the manufacturer, but that there was no serviceable tag for the component. Regarding the “Needs Test” notation in the log book, the mechanic stated that the owner had hover taxied the helicopter onto a trailer prior to it being transported from Kansas to South Dakota. The pilot informed the mechanic that the throttle system performed normally at that time.

NTSB Probable Cause

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