Meeker, CO, USA
N8533F
BELL 206
The helicopter pilot was conducting a low-altitude pipeline patrol in a valley in a remote mountainous area. Two witnesses observed the helicopter flying toward them at a low altitude when the helicopter struck the wires of a three-phase electrical distribution line that was suspended 95 feet above the valley. The main rotor system separated from the helicopter in flight and came to rest about 200 feet from the main wreckage. The pilot stated that he never saw the wires, but that as he felt the impact, he knew immediately that he had struck wires. The on-scene investigation found no preimpact anomalies.
HISTORY OF FLIGHT On November 3, 2010, about 1459 mountain daylight time, N8533F, a Bell 206B helicopter, was substantially damaged after impacting terrain following an in-flight wire strike near Meeker, Colorado. The pilot received serious injuries and the observer was fatally injured. The helicopter was registered to Kauffman Well Service, Inc., Denver, Colorado, and was being operated by Mile High Helicopter Company doing business as Aviation Technology Services, LLC, Englewood, Colorado. Visual meteorological conditions (VMC) prevailed at the time of the accident and a flight plan had not been filed for the 14 Code of Federal Regulations Part 91 pipeline patrol flight. The helicopter departed Grand Junction Regional Airport (GJT), Grand Junction, Colorado, about 1156 destined for Meeker Airport (EEO), Meeker, Colorado. The pilot was conducting a low altitude pipeline patrol in a helicopter equipped with sensor equipment that could detect and record the location of plumes of Methane gas. The observer, sitting in the left cockpit seat, was operating the sensor recording equipment during the flight. At the time of the accident, the pilot was flying westbound, following a pipeline that was buried next to a gravel road at the bottom of a valley in a remote mountainous area. Two witnesses, located about 1,300 feet west from the accident site observed the helicopter flying toward them about 100 to 150 feet above the ground when they saw the helicopter suddenly pitch 90 degrees directly nose down. They saw the rotor system then separate from the fuselage and the helicopter disappeared from their view falling behind a stand of trees. The main wreckage came to rest under a three-phase electrical distribution line which was suspended 95 feet above and perpendicular to the gravel road. The electrical wires were supported by poles about 680 feet apart on either side of the valley. The main rotor system separated from the helicopter and came to rest about 200 feet from the main wreckage. The pilot stated he never saw the wires, but as he felt the impact he knew immediately what had happened and that he had struck wires. He also said the observer sometimes had information about some wires in their flight area ahead, but in this case she never mentioned them before the impact. PERSONNEL INFORMATION The pilot’s logbooks were not available for examination. A review of Federal Aviation Administration (FAA) airman records, the operator’s pilot records, and statements from the pilot, revealed that the 50-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, rotorcraft-helicopter, and instrument helicopter. He additionally held a certified flight instructor (CFI) certificate with a rating for rotorcraft helicopter. The pilot held a second-class medical certificate issued without limitations on May 24, 2010. The pilot reported that he had accumulated a total flight time in all aircraft of about 15,800 hours. 14,500 of those hours were in turbine powered helicopters, with about 12,500 hours of that experience in Bell 206/222/406 helicopters. His most recent flight review was completed on June 30, 2010. AIRCRAFT INFORMATION The model 206B helicopter, serial number 254, was originally manufactured in 1968 by Bell Helicopter Company as a model 206A helicopter and had been converted to a model 206B in 1976. The helicopter was equipped with a 420 shaft horsepower Rolls-Royce M250-C20B gas turbine engine, serial number CAE 834315. The helicopter's maintenance logbooks were not available for examination. The operator indicated on the NTSB Pilot/Operator Aircraft Accident/Incident Report that an annual inspection was completed on July 23, 2010. The operator estimated the helicopter had flown about 73 hours since that annual inspection. At the time of the accident the helicopter had an estimated total airframe time of 26,114 flight hours and an estimated total engine time of 16,027 flight hours. The helicopter was equipped with a wire strike protection system which consisted of an upper and lower fuselage deflector/cutter, and a serrated windshield center post deflector channel. It was also equipped with a Boreal Laser system installed on the belly of the helicopter which could detect plumes of Methane gas. The equipment could record the survey data, the on-board cockpit intercom audio, an externally mounted video camera, and the GPS location. A laptop computer at the observer’s position in the cockpit gave the observer the capability to analyze all of that data while in-flight and to later print out the specific survey results for their customer. Pedal controls were installed at both the left and right cockpit seat positions. The pilot’s station at the right cockpit seat position was equipped with controls for the cyclic and collective. The removable controls for cyclic and collective at the co-pilot’s left cockpit seat were not installed. METEOROLOGICAL INFORMATION The closest aviation weather observation station was Meeker Airport (KEEO), Meeker, Colorado, located 9 miles south from the accident site, at an elevation of 6,421 feet mean sea level (msl). The 1453 surface weather observation showed the wind was from 210 degrees at 6 knots, visibility 10 miles, clear of clouds, temperature 16 degrees Celsius, dew point temperature 1 degree Celsius, and an altimeter setting of 30.50 inches of Mercury. According to the National Oceanic and Atmospheric Administration, about 1500 at the accident location, the altitude of the sun was about 27 degrees, and the azimuth of the sun was about 214 degrees. Solar noon occurred about 1255, and apparent sunset occurred about 1806. WRECKAGE AND IMPACT INFORMATION The main wreckage of the helicopter was observed at rest on its left side about 60 feet west from the intersection of a gravel road, which ran generally east-west, and the power lines, which ran generally north-south. The fuel cell was ruptured and there was a significant fuel spill, but there was no postimpact fire. At the scene two of four wires of the three-phase electrical distribution line were observed to have separated and fallen to the ground. The main wreckage came to rest 60 feet west of the other two wires which remained suspended. Two of the four wires remained suspended and were measured with an inclinometer as about 95 feet above the center of the gravel road. One of the two remaining wires was later removed by utility workers from White River Electric Association (WREA) who reported that the distribution line was unpowered. Several separated ends of the wire exhibited surface damage consistent with being rubbed sideways across a hard sharp metal surface. The main rotor hub with most of both of the main rotor blades separated at the top of the main rotor mast. The main rotor components were observed about 200 feet to the northwest from the main wreckage. The tail boom and tail rotor system remained attached to the fuselage. The tail rotor driveshaft was fractured with torsional signatures just forward of the tail rotor gearbox. The tail rotor blades were bent chordwise and displayed impact damage. The forward section of the cockpit was severed from the main wreckage and found lying in a debris field with the instrument console and cockpit floor. The main rotor system was fractured at the mast and sections of main rotor blades were discovered in the surrounding area. Witness marks and abrasions corresponding to wire damage were noted on the main rotor blades and the cockpit external surface. The main rotor transmission was displaced about 30 degrees forward relative to the aircraft longitudinal axis and remained attached to the aircraft. The transmission input shaft was fractured from the housing and circumferential scars were noted on the shaft consistent with contact between the shaft and firewall opening during rotation. The firewall was compromised during the event and debris was noted near the engine inlet. The first stage compressor blades exhibited foreign object damage (FOD) with metal deformation opposite the direction of travel apparent. However, all first stage compressor blades remained attached to the wheel. Damage to the airframe precluded verification of throttle and collective continuity to the fuel control unit and power turbine governor. The engine remained attached to the aircraft with crushing damage noted to the outer combustion case and left compressor air discharge tube. The engine N2 system turned and remained continuous to the freewheeling unit and the N1 system turned continuously to the starter. Fuel was observed in the engine fuel filter bowl and approximately two tablespoons of fuel was observed in the line from the fuel line check valve to the fuel nozzle. The fuel nozzle was normal in appearance with some carbon formation on the air shroud. The engine mounted fuel filter was normal in appearance. Both the upper and lower magnetic chip detectors were oil wetted and retained some metallic paste and slivers around the outer and inner contacts. This debris was considered normal and would not bridge the gap enough to produce a cockpit enunciation. The aircraft was equipped with a scavenge oil filter and the pending bypass indicator was not extended. All external lines and fittings were secure when checked by hand with no cracks noted. The fourth stage turbine wheel was undamaged. The first stage turbine wheel, turbine nozzle and nozzle shield were normal in appearance when inspected via borescope. The lower wire strike device exhibited evidence of paint and metallic distortion on the cutter blade surface consistent with striking and cutting a wire. The honeycomb floor in the cockpit was sliced through beginning forward of the pilot left pedal and angling aft through the copilot side of the helicopter. Evidence of wire markings were observed on the bottom of the helicopter nose near the copilot seat. The left flight step near the left forward cross tube had a gouge mark consistent with being struck by a wire. Also, a main rotor blade exhibited evidence of span wise after body (blade material aft of spar) separation from contact with a wire Flight controls were installed at the right seat pilot station and tail rotor control pedals were located at both the pilot and the left seat copilot station. The removable cyclic and collective control sticks for the copilot seat were observed to be removed and stowed in the baggage compartment. Both the pilot cyclic and collective sticks in the right cockpit position were separated and exhibited signatures of overload fractures at the base of each stick. The cyclic yoke could not be moved by hand. Main rotor control tubes in the vertical tunnel were not fractured but were jammed against each other and the sides of the damaged vertical tunnel preventing cyclic control movement. On the collective stick, the throttle was observed in the full open position. The collective controls were also not able to be moved because of the vertical tunnel damage. All main rotor control tubes transiting the vertical tunnel were observed to be connected to their respective servos. All cyclic control tubes from the main rotor servos to the non-rotating inner ring swashplate remained connected, although the right cyclic vertical control tube to the swashplate was bent consistent with impact forces. The control tubes from the collective servo were intact to the collective lever. The tail rotor controls exhibited significant damage. Both sets of pedals had separated from their installed positions consistent with wire strike and impact forces. At several locations in the tail rotor control system, control tubes exhibited overload fractures as the result of the wire strike and impact damage. The rotating swashplate rotated freely by hand. Both pitch change links fractured consistent with overload forces near the bottoms of each link. The mast was slightly bent and fractured below the static stop contact area consistent with mast to hub contact during the impact sequence. Drive continuity through the main transmission was established by rotating the main driveshaft coupling adapter by hand and observing rotational movement of the mast. No chips were observed on the transmission chip detectors. The transmission was observed to have rocked forward during the impact sequence which allowed the main driveshaft to disconnect at the forward end. The outer forward coupling on the main driveshaft exhibited radial fractures consistent with overload and misalignment during impact. The freewheeling unit was demonstrated to operate properly. The steel tail rotor driveshaft forward spline coupling had separated from the freewheeling unit drive splines as result of airframe movements and damage during impact, but both were intact. All hanger bearings on the tail boom rotated freely by hand. The aft tail rotor driveshaft on the tail boom exhibited overload fracture surfaces. All four tail rotor gearbox studs had fractured consistent with overload. The tail rotor gearbox chip detector was observed with no chips. The forward cross tube was flattened on the left side and the left skid fractured in several locations consistent with a left side impact. The aft cross tube was fractured on the left side in overload. Neither the left or right skid toes showed evidence of impact damage. All observed damage to the landing gear was consistent with wire strike and impact forces. The Boreal Laser sensor was damaged, but remained mostly connected to its mounting brackets. The helicopter exhibited extensive airframe damage from the impact. The left front of the helicopter exhibited crushing. The tail boom was located in-line with the fuselage, but the tail boom had almost completely separated from the aft fuselage near the attach point consistent with impact forces. Inertial shoulder harness reels on both crew seats were observed and were removed for later examination. The observer in the left copilot seat was reportedly found by first responders to be secured by the 4-point harness, but the observer’s right shoulder fitting was found disconnected and both seat belt straps had been cut by first responders. The pilot seat right shoulder harness fitting and right lap belt fitting were observed to be disconnected at the accident site. The seat belts and shoulder harnesses from both cockpit seat locations were also removed for later examination. The majority of the main rotor hub and blade assembly was found approximately 200 feet northwest from the main wreckage. The main rotor exhibited several spar fractures and all major pieces were observed at the scene. A fractured and separated center section from the S/N A-225 main rotor blade was found about 60 feet from the main wreckage stuck in the ground under the wires. Nearby a 6 foot blade tip section from that main rotor blade was also found under the wires. On the leading edge of the blade near the outboard spar fracture approximately 6 feet from the tip; a shiny section was observed where material was removed from the leading edge consistent with contact with a wire strike. The A-4699 main rotor blade exhibited black transfer to the leading edge consistent with coating found on outside surface of the 3-strand steel/copper “Amerductor” wire. A spar overload fracture of the blade occurred just outboard of the last inboard doubler. The blade exhibited a section of blade after body that was cut almost parallel to the spar and was separated from the blade consistent with a wire strike impact. At approximately 2/3 blade span location, leading edge scrapes and serrations on the bottom blade spar were observed on the blade consistent with a wire strike impact. Small pieces of coiled main rotor top and bottom skin approximately 2 inches wide were observed. Both tail rotor blades remained attached to the tail rotor hub. Each blade exhibited inboard chordwise bends and outboard chordwise bends consistent with ground contact with little to no rotor rpm. An emergency locator transmitter (ELT) identified as an Artex ELT-200 was found at the scene. It had been ejected from its mounting bracket in the left forward cockpit area. It had impact damage that removed the E
The pilot's failure to maintain clearance from electrical power lines during the low-altitude flight.
Source: NTSB Aviation Accident Database
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