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|Accident date||December 27, 2001|
|Aircraft type||Hughes 369E|
|Location||Park City, UT
Near 40.751389 N, -111.721667 W
HISTORY OF FLIGHT
On December 27, 2001, at 1241 mountain standard time, a Hughes 369E, N280SP, registered to and operated by Helicopters by Oz, Inc., dba Helicopter Capture Services of Marysvale, Utah, struck electrical transmission wires and impacted water while maneuvering 15 miles northwest of Park City, Utah. The commercial pilot, another company employee, and a Utah Division of Wildlife Resources employee were fatally injured. Instrument meteorological conditions prevailed, and no flight plan had been filed for the public use flight being conducted under Title 14 CFR Part 133/135. The flight originated from a staging area about 5 miles east of the accident site approximately 1230.
The helicopter had been contracted by the State of Utah to relocate moose from Parleys Canyon to an area 5 miles east, where they would be less hazardous to traffic on Interstate Highway 80. According to the pilot's son and rescuers, the pilot was in the left front seat, the net gunner was in the right front seat, and the Utah Division of Wildlife Resources employee was in the right rear seat. An animal net capturing device was installed in the left front skid. He said the crew had transferred four moose to the staging area that morning. The helicopter landed and the crew had lunch, and then the pilot gave a brief interview to a local television station. They departed the staging area and returned to the reservoir, where the pilot's son disembarked. He watched as the crew attempted to herd a moose off the frozen Mountain Dell Reservoir and back towards the shoreline. When they had done so, the helicopter turned and flew into the power lines.
According to a PacifiCorp spokesman, there was a total of five cables: two static cables on top and three phase (transmission) cables below. The latter cables were 397.5 ACSR (aluminum coarse steel reinforced) and 3/8-inch EHS (extra high strength steel), each carrying 80,000 volts phase-to-ground, and 138,000 volts phase-to-phase. The power lines were supported by two twin towers, each about 400 feet tall, and 921 feet apart. The point of impact was 108 feet above the frozen surface. The first recorded circuit breaker trip was at 1241:00.
Witnesses said it appeared the helicopter initially struck the lower of the two static wires, nosed over, and fell in a near-inverted attitude to the surface of the frozen reservoir. It broke through the ice, sank, and then floated back to the surface. The tail rotor and aft portion of the tail boom remained entangled in the wires. Rescuers were able to attach a line and winch the helicopter ashore.
The accident occurred during daylight hours at a location of 40 degrees, 45'05" north latitude, and 111 degrees, 43'18" west longitude. Mountain Dell Reservoir is at an elevation of 5,505 feet msl.
The 49-year-old pilot possessed a commercial certificate with a single-engine land, multiengine land and helicopter ratings. His second class airman medical certificate, dated August 23, 2001, contained no restrictions or limitations, but a waiver for color vision had been issued. His last 14CFR135 check ride was accomplished on April 17, 2001. His most recent logbook, containing entries from December 5, 2000, to December 21, 2001, contained the following flight times:
Total time 6,542.3 Pilot-in-command 6,418.3 Helicopter 6,129.4 Solo 6,391.3 Cross-country 609.4 Hughes 369E 563.3 Night 38.9
N280SP, a model 369E (s/n 0169E), was manufactured by the Hughes Helicopter Corporation in 1986. It was equipped with an Allison 250-C20R2 engine (s/n CAE-295277), rated at 450 shaft horsepower. The last 100-hour airframe and engine inspections were accomplished on December 18, 2001, at a Hobbs meter reading of 191.3 hours. At that time, the airframe had accrued 8,398.3 hours. and the engine had accumulated 2,529.55 hours since new. Total engine cycles were 1,778. The last daily Aircraft Flight and Maintenance Log sheet, filled out on the morning of the accident, indicated the Hobbs meter read 203.0 hours, total engine hours were 2,542.2, and total engine cycles were 1,784.
According to ground witnesses, the weather at Mountain Dell Reservoir at the time of the accident was, visibility approximately 1 mile in fog.
WRECKAGE AND IMPACT INFORMATION
The on-scene investigation commenced and terminated on December 28, 2001. Investigators from Boeing (formerly Hughes and McDonnell Douglas) Helicopters and Rolls-Royce (formerly Allison and Allied Signal) Engines examined the stored wreckage at Spanish Fork, Utah, on March 21, 2002, under the supervision of an inspector from FAA's Flight Standards District Office in Salt Lake City. According to Boeing's report, the cockpit area -- from F.S. (fuselage station) 0.0 aft to F.S. 64.37 -- was crushed and separated and the fuselage, to F.S. 102.23, was buckled and crushed. The right forward landing gear leg and skid tube exhibited "chatter" marks, similar to abraded wire scuffing. The tail boom was severed into three segments, with fractures at F.S. 221.0 and 253.0. There were paint transfer marks around this fracture area similar to the paint on the main rotor blade. There were also gashes in the tail boom consistent with main rotor blade strikes.
The empennage (tail rotor transmission, tail rotor, gear box, horizontal stabilizer and vertical stabilizers) remained attached to a 27-inch section of the aft portion of the tail boom. It was severed at F.S. 253.0. There were burn marks on the upper portion of the vertical stabilizer, around the tailskid mount, and at the horizontal stabilizer's right tip cap. There was extensive structural damage to the entire airframe. This was the section that was entangled in the power lines.
Power continuity was established from the main transmission to the tail rotor. The main transmission rotated when the main rotor system was turned by hand, and drive from the transmission to the tail rotor output pinion and drive shaft continued when the main transmission was turned by hand. The tail rotor gearbox appeared normal when rotated by hand.
The main rotor hub assembly and components exhibited damage commensurate with sudden stoppage. The main rotor blades were bent, cut, and gouged, and the spars were fractured. The blade surfaces were wrinkled and delaminated, and there were trailing edge separations. There were numerous paint transfer and wire contact marks.
All cyclic, collective, and anti-torque control linkages forward of C.S. (canted station) 78.50 were fractured, crushed, or absent. Lateral and longitudinal cyclic control continuity was lost due to numerous breaks in the linkage. The throttle twist grip could not be rotated. Collective pitch control continuity was established to the bellcrank. Anti-torque control continuity between F.S. 78.50 to F.S. 221.0 and aft of F.S. 253.0 was established.
None of the engine mounts were damaged and the engine remained in place, exhibiting no visible damage. A fuel system vacuum check produced no noticeable loss of pressure. Fuel was present in the fuel filter, pump, and nozzle. There was oil in the engine. Engine control continuity could only be established between F.S. 78.50 and F.S. 84.0.
MEDICAL AND PATHOLOGICAL INFORMATION
On December 28, 2001, an autopsy was performed on the pilot by the Utah State Medical Examiner's Office. Death was attributed to blunt force injuries. Both the medical examiner's office and FAA's Civil Aeromedical Institute (CAMI) conducted toxicological screens. Both reports disclosed no evidence of ethanol, cyanide, carbon monoxide or drugs.
TESTS AND RESEARCH
The engine installed in N280SP was a "loaner" engine. Because it had a reported history of compressor stalls, it was decided to functionally test the engine at Rolls-Royce's facilities in Indianapolis, Indiana. This was done on May 3, 2002, under the supervision of an inspector from FAA's Flight Standards District Office in Indianapolis. According to Rolls-Royce's report, the engine was successfully started five times. Stabilized running, time accelerations, and a power calibration were conducted. The engine met or exceeded new engine specification in all parameters. "Type II" wave offs were conducted several times in an attempt to induce compressor stalls. No stalls were noted.
The overrunning clutch assembly, part number 369A5350-41, was removed and shipped to Boeing in Mesa, Arizona, where, on May 21, 2002, it was disassembled and examined under the supervision of an inspector from FAA's Flight Standards District office in Scottsdale, Arizona. According to Boeing's report, the clutch housing and seal were damaged by impact. Disassembly revealed clean, dark green oil with no odor of burning. The component passed the "4-way" check indicating the sprags functioned properly. The bearings contained plenty of grease with no discoloration or contamination. There was no evidence of wear.
In addition to the Federal Aviation Administration, parties to the investigation included Rolls-Royce Engines and Boeing Helicopters.
At the conclusion of all tests, the wreckage was released to the insurance company adjuster on May 21, 2002.