CHI01LA243

While maneuvering during an aerial application flight, the helicopter impacted a power transmission line and subsequently impacted the terrain. The pre-impact height of the power transmission line was approximated to be 42 feet. The tailboom assembly, including the tail-rotor, was found approximately 125 feet from the main wreckage. No anomalies were found during the post-accident inspection that could be associated with any pre-impact condition.

History of flight

On July 26, 2001, at 0940 central daylight time, a Bell 47G-2, N986B, was substantially damaged during an in-flight collision with power lines and subsequent collision with the terrain near Wheeler, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was operating under the provisions of 14 CFR Part 137 and was not on a flight plan. The pilot, the sole occupant, was fatally injured. The local flight departed at 0930.

According to a witness to the accident, the helicopter approached from the east and attempted to clear some power transmission lines and impacted the top wire, subsequently impacting the terrain. The witness reported that a fire started subsequent to the helicopter impacting the terrain.

Another witness reported hearing a power line pole breaking and saw the helicopter impact the terrain. The witness stated that a fire started after the helicopter impacted the terrain.

The witness statements are appended to this factual report.

Personnel information

According to Federal Aviation Administration (FAA) and Transport Canada records, the pilot was the holder of commercial pilot certificate with a rating for helicopters. The pilot also held an airline transport pilot certificate and was certified for single-engine land/sea airplanes and multiengine land airplanes. The pilot was instrument rated. According to FAA records the pilot completed his last aviation medical examination on May 9, 2001, and was issued a second-class medical certificate with the limitation, "Must wear corrective lenses and possess glasses for near and intermediate vision."

The pilot was reported to have had accumulated a total time of 9,839.2 hours as pilot-in-command (PIC), of which 5,889.4 hours were in helicopters and 3,949.8 hours were in airplanes. The pilot had accumulated a total of 500 hours as PIC in the accident helicopter make and model. The pilot had flown 75 hours during the last 90 days, all of which were in the same make and model as the accident helicopter. The pilot had flown 65 hours during the last 30 days and 8 hours during the last 24 hours.

Aircraft information

The helicopter was a Bell 47G-2, serial number 1399. At the time of the accident, the helicopter had accumulated 9,752.3 hours since new. The helicopter's last annual inspection was on May 1, 2001, and the helicopter had accumulated approximately 10 hours since the last inspection.

The engine was a 265 horsepower Lycoming VO-435-A1F, serial number L-2733-52. At the time of the accident, the engine had accumulated 1,093.0 hours since the last overhaul.

Meteorological information

A weather reporting station, located at the Chippewa Valley Regional Airport, approximately 22 nautical miles southeast of the accident site, reported the weather at 0956 as:

Wind: 090 degrees magnetic at 9 knots

Visibility: 10 statute miles

Sky Condition: Sky Clear

Temperature: 20 degrees Celsius

Dew Point: 09 degrees Celsius

Pressure: 30.25 inches of mercury

Wreckage and impact information

The wreckage was located in an agricultural field and a downed power transmission line was found near the accident site. The power transmission lines ran parallel to a north/south-orientated road that was adjacent to the agricultural field in which the main wreckage was located. The pre-impact height of the power line was reported to be 42 feet. The helicopter's tailboom assembly, including the tail-rotor, was found approximately 75 feet west of the road. The main wreckage was found approximately 125 feet from the tailboom assembly, or 200 feet west of the road. During a post-accident inspection of the aircraft, no anomalies were found with the helicopter, or its related systems, that could be associated with any pre-impact condition.

Medical and pathological information

An autopsy was performed on the pilot at the Sacred Heart Hospital, Eau Claire, Wisconsin, on July 26, 2001.

A Forensic Toxicology Fatal Accident Report was prepared by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma, for the pilot.

The toxicology results for the pilot were:

* No Carbon Monoxide detected in Blood

* No Cyanide detected in Blood

* No Ethanol detected in Vitreous

* 1.549 (ug/ml, ug/g) Acetaminophen detected in Blood

Survival aspects

The Dunn County Medical Examiner reported that there was a helmet found at the accident site, but the pilot was not wearing the helmet at the time of the accident. The Medical Examiner reported that the pilot was not wearing the available shoulder harness at the time of the accident, but was wearing the lap belt. The inboard lap belt attachment point was found pulled loose from the supporting aircraft structure.