Aviation Accident Summaries

Aviation Accident Summary ATL02FA003

N. Wilkesboro, NC, USA

Aircraft #1

N8104J

Bell 206B

Analysis

The helicopter collided with power lines in cruise flight approximately 130 feet above the ground, then collided with the ground and burst into flames. Power line cable 3/4-inch in diameter was found wrapped several times around the transmission mast, and the helicopter was not equipped with a Wire Strike Protection System. Examination of the airframe and powerplant revealed no evidence of mechanical malfunction. It was observed that the rising terrain to the west of the accident site cast a shadow over the power lines at the time of the accident.

Factual Information

HISTORY OF FLIGHT On October 22, 2001, at 1838 eastern daylight time, a Bell 206B helicopter, N8104J, registered to Saber Executive Helicopters, Inc., and operated by Saber Cargo Airlines, Inc., collided with power lines in the vicinity of North Wilkesboro, North Carolina. The flight was operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The commercial pilot and the passenger received fatal injuries, and the helicopter was destroyed. The flight departed Wilkes County Airport in North Wilkesboro, North Carolina, at 1835. The operator stated the pilot's standard routine included a delivery of cargo to a facility in North Wilkesboro, North Carolina, under the provisions of Title 14 CFR Part 135, and the carriage of a passenger was unauthorized. The passenger met the pilot at the North Wilkesboro, North Carolina, facility and boarded the helicopter, then the flight proceeded to Wilkes County Airport in North Wilkesboro, North Carolina, for fueling. The flight departed the airport with 50 gallons of Jet A aviation fuel on board. According to the Wilkes County Sheriff's Department, the passenger called his brother from the helicopter with his cell phone. The brother was at a location about 4.5 nautical miles south of the Wilkes County Airport, and the passenger told him, "We are about over the top of you." The brother stated he could hear the helicopter in the background, and he went outside and observed the helicopter fly overhead in a straight line about 500 feet above the ground before it disappeared from view. A witness on the ground, about 4 nautical miles south of the Wilkes County Airport, observed the helicopter flying at a low altitude along a valley pasture bounded by rising terrain and trees. The witness saw the helicopter flying toward power lines that crossed the valley, and the witness ran to avoid what he believed was an imminent collision. The witness stated he saw the helicopter collide with the power lines, then fall to the ground and burst into flames. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with ratings for rotorcraft helicopter and instrument helicopter. He held a second class medical certificate issued on May 29, 2001, with no waivers nor limitations. The pilot 's log book was not recovered. His total flight time as estimated by the operator was 4,500 hours with 3,000 hours in the Bell 206B. AIRCRAFT INFORMATION The Bell 206B was powered by an Allison 250-C20 400-horsepower turbine engine. Examination of the helicopter log books revealed a 100-hour inspection was completed on August 9, 2001, at an engine total time of 11,907.3 and airframe total time of 16,402.6. A copy of a Daily Aircraft Flight Record provided by the operator indicated the airframe had a total time of 16,507.5 on October 15, 2001. The helicopter was not equipped with a Wire Strike Protection System. METEOROLOGICAL INFORMATION The Hickory Regional Airport, Hickory, North Carolina, automated weather station reported at 1753 conditions were wind 220 degrees at 12 knots, sky clear, visibility 10 statute miles, temperature 79 degrees Fahrenheit, dew point 61 degrees Fahrenheit, and altimeter 30.01 inches. WRECKAGE AND IMPACT INFORMATION Examination of the accident site revealed the wreckage came to rest approximately 75 feet north of severed power lines that crossed a north-south oriented pasture valley and stream. The power lines were supported by two 90-foot utility towers atop rising, wooded terrain on the east and west sides of the valley, and the height of the remaining unbroken power lines was approximately 130 feet above the valley floor. The wreckage was found resting on its right side facing west in the stream and was mostly consumed by post-impact fire. Portions of the roof deck, engine firewalls, and the left aft door were not consumed. The landing skids were separated, and the forward cross tube remained attached to the left skid and was found approximately 10 feet from the fuselage left side. The aft cross tube was separated and found approximately 10 feet from the fuselage right side, and the right skid was fractured into several pieces. Both cross tubes were bent inward on the right side. The tail boom was found with the tail rotor blades and the horizontal stabilizer attached. The right horizontal stabilizer displayed crush damage, the vertical stabilizer was separated and displayed impact damage, and the tail rotor gearbox was separated from the mount. The tail rotor blades were bent uniformly outward approximately seven inches from the hub. The tail boom forward of the horizontal stabilizer was consumed by post-impact fire. The transmission mast was fractured below the main rotor head static stops, and the main rotor head was found separated and resting adjacent to the engine and transmission assembly. Power line cable 3/4-inch in diameter was found wrapped several times around the transmission mast. The inboard portions of both main rotor blades remained attached to the rotor head. One blade displayed bending and twisting with the outboard tip separated. The other blade was separated into four sections, with one section found embedded 18 inches into the ground adjacent to the main rotor head, and the other two sections found approximately 90 feet west of the wreckage. Examination of the flight controls revealed the drive link, the collective lever, the swashplate support tube, and the rotating and non-rotating swashplates were intact. The pitch links were separated at the swashplate attach clevises. The control linkage to the non-rotating swashplate and the hydraulic boost actuators were damaged by post-impact fire. The tail rotor gearbox rotated freely when turned, and the chip plug was free from debris. Pitch control to the tail rotor blades was established to the point of tail boom separation. Examination of the engine and transmission assemblies revealed the turbine was split apart at the power turbine support, and about half of the accessory gearbox was consumed by post-impact fire. The compressor displayed foreign object damage on the trailing edge of the inlet guide vanes and on the first stage compressor blades. The compressor bleed valve poppet traveled freely from the open to closed position. The outer combustion case and the combustion liner were undamaged, and the air baffles of the combustion liner displayed no evidence of abnormal deposits. The turbine was removed from the gearbox for examination. The N1 rotor system rotated freely, and the N2 rotor system rotated with some difficulty. The turbine displayed aluminum splatter on the first stage nozzle shield, the first stage nozzle guide vanes, the second stage blades, and on the suction side of the third stage nozzle guide vanes. The main mast spline alignment was distorted. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot on October 24, 2001, by the North Carolina Baptist Hospital, Department of Pathology, Winston-Salem, North Carolina. The report stated the cause of death was multiple blunt force injuries. Forensic toxicology was performed on specimens from the pilot by the Federal Aviation Administration Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma. The report stated no ethanol was detected in the vitreous, and no drugs were detected in the kidney. ADDITIONAL INFORMATION A review of U.S. Naval Observatory astronomical data for the location of the accident revealed the altitude of the sun at 1838 eastern daylight time was 0.2 degree at an azimuth of 256.4 degrees, the altitude of the moon was 28.9 degrees at an azimuth of 183.3 degrees, and the illumination of the moon was 39 percent. Sunset was 1840 eastern daylight time, and the end of civil twilight was 1906 eastern daylight time. At the accident site on October 23, 2001, at 1838, it was observed that the rising terrain to the west cast a shadow over the pasture valley and power lines. The wreckage was released to the insurer on December 17, 2002.

Probable Cause and Findings

The pilot's failure to maintain visual lookout and clearance above obstacles, which resulted in a collision with power lines and subsequent loss of control and collision with terrain.

 

Source: NTSB Aviation Accident Database

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