History of Flight
On April 21, 2017, at about 1632 eastern daylight time, a privately owned Bell-Carson 47G Super C-4 helicopter, registration N865Z, was destroyed by impact forces and a postcrash fire near a private uncharted airfield in Timmonsville, South Carolina. The private pilot was fatally injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The helicopter departed Huggins Memorial Airport (58J) in Timmonsville about 1628.
According to the pilot's family, the purpose of the flight was to conduct a "golf ball drop" at a fundraising event located about 13 miles northwest of the accident site. The family was not aware of the planned route or any possible stops.
A review of Federal Aviation Administration (FAA) radar data, which did not include altitude information, showed that after departure from 58J, the helicopter flew northwest toward the golf ball drop location. The last recorded radar data point was about 800 feet north of the accident site, at which time the helicopter was flying northwest, away from the accident site, and its track was not aligned with the turf runway at the private airfield or the accident site. The flight path and timing after the radar data ended could not be determined.
A witness at the private airfield residence, about ¼ mile from the accident site, heard the helicopter and thought it might be approaching the airfield, but could not see it due to trees. The witness reported hearing the rotor blades, then the engine sound becoming louder, followed by the sound of rotors hitting trees and an explosion. A black plume of smoke was seen rising from a neighboring yard.
Personnel Information
The pilot held a private pilot certificate with ratings for airplane single-engine land and rotorcraft-helicopter. His most recent FAA third-class medical certificate was issued on September 26, 2014, at which time he reported 3,600 hours of total flight experience. The medical certificate expired in September 2016. The pilot's logbook was not recovered, so his flight experience in this make and model and total hours flown between the medical certificate and the accident could not be determined.
Aircraft Information
The four-seat Bell-Carson 47G Super C-4 helicopter was manufactured in 1962 and assembled by Carson Helicopters from Bell Helicopters components. It was powered by a 235-horsepower, six-cylinder Franklin 6V350A engine. The helicopter's logbooks were consumed by the postcrash fire, so maintenance history and operational times could not be determined.
Meteorological Information
The nearest weather reporting station was Florence Regional Airport (FLO), about 14 miles east of the accident site. At 1653, the reported weather included wind from 220° at 12 knots, visibility 10 miles, few clouds at 6,500 feet, temperature 31°C, dewpoint 15°C, and an altimeter setting of 29.90 inches of mercury.
Wreckage and Impact Information
All major components were accounted for. The initial impact was a freshly cut treetop about 60 feet above ground at the tree line. The tail rotor personnel guard and left horizontal stabilizer were found near the base of the damaged tree. The main wreckage path was about 100 feet long on a magnetic heading of about 325°. Fragments of the main rotor blades were scattered within a radius of about 300 feet. The initial ground scar was about 90 feet beyond the first tree strike. The main wreckage came to rest inverted on a 2-acre residential lawn about 100 feet to the right of the turf runway extended centerline and about 300 feet from the runway threshold. The turf runway, oriented 330°, had not been recently maintained and had grass about 4 feet tall.
The helicopter came to rest inverted on a heading of about 210° and was partially consumed by fire. The tail rotor gearbox remained attached to the tailboom, which separated at the aft center frame and was located about 50 feet southeast of the main wreckage. The right landing skid separated from both cross-tubes; the left skid remained attached to the front cross-tube. The engine, transmission, and rotor mast remained together, partially attached to the airframe, and rotated about 90° aft. The main rotor hub remained mounted with both blade grips attached. The two wooden main rotor blades were fragmented. One blade grip retained the metal spar and a 10-foot section; the other grip retained the metal spar and a 1-foot section. The tail rotor driveshaft was bent upward just forward of the gearbox input quill, with tree bark observed at the bend. The tail rotor gearbox rotated freely after the driveshaft was removed. Both metal tail rotor blades were fractured just outboard of the grips, with minor bending damage.
Cyclic control pedestals were damaged and separated. Collective control stick remnants were separated and mostly consumed by fire. Anti-torque pedal assemblies remained connected but separated from the structure. Two cables were attached to the damaged tail rotor quadrant and were continuous to overload breaks at the aft center frame. One cable attached to the tail rotor pitch control assembly had an overload break near the forward end of the tailboom; the pitch control mechanism moved smoothly when the cable was pulled. The engine accessory section was damaged, with fragments exposing accessory gears. The starter, hydraulic pump, and both magnetos were separated and fire damaged. The carburetor was partially attached; mixture control remained; throttle control rod end was fractured consistent with overload. The carburetor heat plenum was separated; control cable remained attached. The crankshaft could not be manually rotated. Most avionics were partially or completely consumed by fire. The transponder could not be identified. Burned paper consistent with maintenance records was found. No remnants of golf balls were found.
Medical and Pathological Information
An autopsy of the pilot was performed, and the cause of death was multiple blunt force injuries. Toxicology testing identified tetrahydrocannabinol (THC) in liver (0.0374 µg/ml) and cavity blood (0.0185 µg/ml) specimens. Tetrahydrocannabinol carboxylic acid (THC-COOH) was found in liver (0.3438 µg/ml), urine (0.3087 µg/ml), and cavity blood (0.0253 µg/ml). The National Highway Traffic Safety Administration Drugs and Human Performance Fact Sheet for marijuana notes that establishing a relationship between THC concentration and performance impairment is difficult, and effects are dependent on pattern of use and dose.