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On July 15, 2008, at 0926 central daylight time (CDT), a Hughes 269B helicopter, N469E, struck a high voltage transmission line and impacted terrain while conducting a power line patrol near Salesville, Arkansas. The commercial pilot and passenger were fatally injured. The helicopter was destroyed. The flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. The flight originated from a non-airport location near Willow Springs, Missouri.
The pilot departed his home near West Plains, Missouri at 0714 and arrived at Willow Springs, Missouri, at 0741. The pilot departed that location at 0748 with an employee of Sho-Me Power Electric Cooperative onboard and they proceeded to follow SHO-ME high voltage transmission lines to look for vegetation encroachment. At the time of the accident the helicopter was following SHO-ME high voltage transmission line 609 (SM-609), which terminated at the Norfork Dam substation. Beginning three quarters of a mile southeast of the Norfork substation SM-609 followed a westerly heading and descended from the top of a ridge into a valley, where it turned north .35 miles south of the substation. Approximately 160 feet east of where SM-609 turns north, an Entergy 161 kilovolt (KV) high voltage transmission line (Ent-161), which ran north-south, crossed perpendicular and above SM-609. Ent-161 was comprised of three high voltage transmission lines, which ran parallel to each other and were suspended below two grounding wires. At the point Ent-161 crossed SM-609, SM-609 measured 51 feet above the ground and Ent-161 was estimated to be 154 feet above the ground at the high voltage transmission line level. Examination of the accident site revealed the middle strand of the Ent-161 high voltage transmission line broken. The main wreckage was located 184 feet from the broken wire on a 280 degree bearing.
The pilot, age 56, held a commercial pilot certificate with ratings for rotorcraft-helicopter. His last Federal Aviation Administration (FAA) second-class medical was issued on July 19, 2007, with the limitation of "Must have available glasses for near vision."
An examination of the pilot's logbook indicated an estimated total flight time of 1,320.1 hours; of which 1,275.2 hours were in helicopters. He logged 134.3 hours in the last 90 days and 77.8 in the last 30 days. His last flight review was completed June 30, 2007.
The pilot's flight log contained entries that he and the passenger had flown together on numerous occasions starting in 2006. There was one record the pilot had flown SM-609 during the previous year with a different Sho-Me Electric employee. The purpose of that flight was to observe the power line poles for disrepair. According to Sho-Me Electric personnel, they terminated the route prior to reaching the location where Ent-161 crossed SM-609.
The passenger was a vegetation control manager for Sho-Me Electric Cooperation. His role on the flight was to observe the areas surrounding the flown power line for vegetation encroachment and any other activities or environmental issues that could affect the power line. Investigators could not determine if the passenger had flown SM-609 before. According to Sho-Me Electric personnel, the passenger normally flew with a map that showed the terrain, obstructions, and crossing power lines and annotated observations in a small notebook. The map and notebook were not located in the wreckage.
The 1965-model Hughes 269B, serial number 45-0186, was a helicopter with fixed skids for landing gear, and was configured for two occupants. The helicopter was powered by a direct drive, horizontally opposed, fuel injected, air-cooled, four-cylinder engine. The engine was a Lycoming HIO-360-A1A, serial number L-6412-51A, and was driving a three-blade main rotor assembly.
According to the airframe logbook, the helicopter's most recent annual inspection was completed on September 24, 2007, with an airframe total time of 1,800.4 hours. The airframe had accumulated 1,888.7 total hours at the time of the accident.
The engine logbook revealed that the engine had been inspected in accordance with an annual inspection on September 24, 2007. At the time of the inspection the engine had accumulated approximately 1074.7 hours since the last major overhaul.
At 0953, the weather observation facility at Mountain Home, Arkansas (KBPK), reported, wind from 190 degrees at 3 knots, visibility 10 miles, clear skies, temperature 76 degrees Fahrenheit, dew point 64 degrees Fahrenheit, and a barometric pressure of 30.14 inches of Mercury.
WRECKAGE AND IMPACT INFORMATION
Examination of the airframe revealed that the main cabin, center section frame, forward section fairing, and transmission were consumed by fire. The fire also burned and damaged the engine. The rotor mast was fractured, separated from the transmission, and was found near the wreckage. All three rotor blades remained attached to the rotor hub and two were bent and twisted throughout their length. The tail boom was separated from the helicopter. The tail rotor assembly was found attached to the tail boom with damage to both tail rotor blade pitch horns and a tail rotor blade.
The main rotor and mast were found next to the burnt wreckage. Control continuity was established from the main rotor system pitch control rods to the non-rotating swash plate, through the rotating swash plate pitch change links, to the main rotor pitch housings which remained attached to the hub.
The helicopter had three main rotor blades. Blade one had visible paint and damage signatures consistent with a strike to the tail boom. The blade remained attached to the main rotor hub. Blade two had surface deformation and multiple surface abrasions along the length of the blade from the blade tip to blade root. Blade two lacked the excessive bends, twists, or surface penetrations of the other two blades and remained attached to the main rotor hub. Blade three exhibited a diagonal braided skid pattern abrasion underneath the entire length of the blade, consistent with striking a wire. The blade had extensive structural damage throughout the blade length and the tip cap was missing. The blade remained attached to the main rotor hub. Note: Party member reports reference Blade one as the "red" blade, Blade two as the "blue" blade and Blade three as the "unmarked" blade.
The tail boom separated from the fuselage structure at the center frame attachments and support strut assembly attachment at the saddle fittings. The tail boom was found in two pieces and damage evidence was consistent with an impact from a main rotor blade at the midpoint. Aft of the midpoint fracture, the tail boom had one other visible damage area just forward of the tail rotor transmission attachment point. The tail rotor assembly and horizontal fin were found attached to the aft section of the tail boom.
The tail rotor transmission assembly sustained no visible damage. Flight control continuity was established to the tail rotor control rods. Both of the tail rotor blades pitch horns were fractured, showing 45 degree fracture surfaces and shear lip signatures. One tail rotor exhibited damage signatures consistent with blunt force flex and bending damage at the midpoint of the blade and separation of the trailing edge from the tip cap to the blade midpoint. The other tail rotor blade contained no visible damage. The horizontal fin was attached to the tail boom with surface damage visible along the spar frame flange.
The engine and engine accessories sustained extensive fire and heat damage. The engine could not be rotated. Engine continuity was verified by lighted Borescope inspection through breaches in the crankcase. The rotating assembly displayed no pre-impact damage or fractures. The starter and vacuum pump were not recovered. The left and right magnetos, alternator, and oil sump were damaged by fire. Nothing was observed that would have precluded the engine from making power prior to impact.
The left door, right collective, and right control stick had been removed prior to the accident flight and were located in the pilot's hanger.
FLIGHT DATA RECORDERS
A Garmin GPSMap 296 was recovered at the accident site. The unit contained 185 track logs, with the first track log dated March 4, 2008. The last track log, dated July 15, 2008, began at 08:14:01 (0714 CDT) and ended at 10:26:04 (0926 CDT). The times retained by the unit were one hour later than that of the actual flight, as substantiated by police report.
The last track originated at coordinates coincident to the pilot's home and proceeded north to a point near Willow Springs, Missouri. There was a delay of eight minutes at Willow Springs and then the track preceded east, then south and southwest following Sho-Me Electic 69 KV transmission lines numbered 502, 621, 637, 812, 672, and 579. The track continued to follow Sho-Me Electric 161 KV transmission lines numbered 610 and 609.
During the last minute of data the track averaged 47.5 miles per hour and 748 feet mean sea level (msl). The last four track-points recorded the following time, airspeed, altitude, and true headings:
10:25:32 45 mph 753 msl 287 degrees
10:25:44 52 mph 674 msl 288 degrees
10:25:57 57 mph 598 msl 288 degrees
10:26:04 51 mph 612 msl 281 degrees
MEDICAL AND PATHOLOGICAL INFORMATION
The Arkansas State Crime Laboratory, Medical Examiner Division, located in Little Rock, Arkansas, performed an autopsy on the pilot on July 17, 2008. The cause of death was determined to be multiple blunt force injuries.
The FAA, Toxicology Accident Research Laboratory, located in Oklahoma City, Oklahoma, conducted toxicological testing on the pilot. Testing was negative for carbon monoxide, cyanide, and ethanol. Naproxen was detected in the urine.