Incident Overview
On April 11, 2008, at approximately 0900 Pacific daylight time, a Bell 47G-3B-1 helicopter (registration N24SD) executed a hard landing on hilly terrain about 25 miles south of Denio, Nevada. The helicopter, operated by Helicopter Roundup Service, LLC, of Nephi, Utah, was conducting an aerial observation flight for predator control when the incident occurred. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated from a private ranch near Denio at about 0700.
Sequence of Events
According to the pilot, the purpose of the flight was predator control, and the passenger-gunman had just shot a coyote. While circling the injured coyote at approximately 20 feet above ground level and nearly in a hover, the pilot heard a grinding noise emanating from the transmission, followed immediately by a loss of power to the main rotors. Prior to the noise, no problems had been noted. The helicopter's airspeed was about 15 miles per hour at the time, and the pilot was unable to perform a successful autorotative descent. The subsequent hard landing caused the skids to collapse, the main rotor blades to sever the tail boom, and the helicopter to roll over. Neither the commercial pilot nor the passenger sustained injuries.
Examination Findings
The helicopter was recovered and examined by Federal Aviation Administration (FAA) and Bell Helicopter personnel. The swashplate and centrifugal clutch for the main rotor system showed no indication of failure. The engine and turbocharger rotated freely, as did the tail rotor drive shaft and tail rotor gear box. No signs of abnormal wear or failure were found in the transmission. The only discrepancy noted by the FAA was that one of the two cooling fan drive belts was not found seated on its pulley, though it was present at the accident site. The FAA suggested that this belt may have rolled over on its pulley and produced a noise that the pilot heard just before it broke. No other anomalies or failures were identified during the examination.
Conclusion
The helicopter sustained substantial damage, but no injuries were reported. The investigation did not identify a definitive cause for the reported loss of power.