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N27TV accident description

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Tail numberN27TV
Accident dateJune 26, 2004
Aircraft typeBell 206B
LocationCushing, OK
Near 36.05 N, -98.750278 W
Additional details: None

NTSB description

HISTORY OF FLIGHT

On June 26, 2004, at 2041 central daylight time, a Bell 206B single-engine helicopter, N27TV, was destroyed when it impacted water following an in-flight collision with power lines while maneuvering near Cushing, Oklahoma. The commercial pilot and a passenger sustained fatal injuries, and three passengers were seriously injured. The helicopter was owned and operated by Interstate Helicopters, Inc., of Oklahoma City, Oklahoma. Visual meteorological conditions prevailed, and no flight plan was filed for the Title 14 Code of Federal Regulations Part 91 sightseeing flight. The local flight departed the Elks Lodge, Cushing, Oklahoma, approximately 2035.

According to the operator, the helicopter was chartered by a private individual to provide sightseeing rides for guests at a birthday party near Cushing. Prior to the accident flight, the pilot had completed four or five previous flights around the town of Cushing.

A witness, who was located outside his residence approximately 9 miles from Cushing, stated that between 1930 and 2030, a white helicopter with blue trim and lettering flew over his property at tree level. The helicopter dropped toward his pond, then immediately pulled up and barely cleared the trees and power lines on the side of his property. The helicopter flew toward a nearby soccer field, dropped down again and pulled up over the end of the soccer field. The helicopter turned and flew back toward Cushing. The witness stated the helicopter was flying "pretty reckless."

A passenger, who flew in the helicopter prior to the accident flight, stated that the safety officer provided "very professional" instructions. The safety officer assisted in the loading and unloading of passengers. During the flight, the passenger thought "the pilot sensed my fear and didn't make any scary moves, just a big loop around the area and back to the Elks Lodge."

According to the passengers' written statements, the passenger who was seated in the right rear seat, reported the safety officer prior to the flight, "explained the rules (head and arms down, no drinks on board, etc...)." The passenger stated the lighting [outside] was good and there was not much wind. The helicopter departed, approached the Cimarron River flying to the west and turned left over the river. After the left turn, the helicopter was banking left and descending. While looking forward, the passenger reported "we hit the unmarked power lines, but [he] never saw them, only flying debris and sparks." The helicopter shook, impacted the water, then bounced and skipped down the water for several hundred yards.

The passenger who was seated in the rear center seat, reported the weather was partly cloudy with a light wind. After securing his seatbelt, the next thing the passenger remembered they were descending toward the Cimarron River. The passenger could see the river and the sun out the front windscreen. While flying over the river, the passenger heard very loud crackling sounds, the helicopter began to violently shake, and then impacted the water.

The passenger who was seated in the left rear seat, reported the visibility was good and a "slight sprinkle" after takeoff. The passenger stated, "pilot flew north to the Cimarron River. Once we arrived he descended to within a few feet over the riverbed and then flew up into the power lines." The helicopter then dropped and impacted the river.

A witness, who was fishing with his son in a boat on the Cimarron River, reported they started fishing approximately 1830. A few minutes prior to the accident, the witness moved his boat under a bridge due to an isolated rain shower in the area. At 2045, the witness heard a crashing sound, then observed a large splash in the water and flying debris approximately 1 mile east of his position. At 2050, unable to obtain a clear signal with his cellular telephone, the witness contacted a relative who then notified the police about a crashed helicopter in the middle of the Cimarron River. Approximately 15 minutes after the accident, rescue personnel arrived near the accident site. Rescue personnel located three individuals hanging on to the accident helicopter. The witness did not see or hear the helicopter on any other flights prior to the accident.

Approximately 2045, the operator's safety officer, who was located at the helicopter's departure point, contacted the owner of Interstate Helicopters Inc. and stated the helicopter was overdue from a flight. Approximately 2100, the safety officer was notified by personnel from the Cushing airport of a downed aircraft in the Cimarron River, approximately 5 miles north of Cushing.

PERSONNEL INFORMATION

The pilot held a commercial certificate with airplane single-engine land, airplane single-engine sea, airplane multi-engine land, rotorcraft, balloon, and instrument airplane ratings. The pilot also held a flight instructor certificate with airplane single-engine land, instrument airplane, and rotorcraft ratings. The pilot's most recent second class airman medical certificate was issued on June 10, 2003, with a limitation for corrective lenses. According to the operator's records, on March 1, 2004, the pilot reported he had accumulated 7,173.8 total flight hours, and 4,929.7 total rotorcraft hours. The pilot's logbook was not located.

A Federal Aviation Administration inspector reported to the NTSB investigator-in-charge (IIC) the pilot inadvertently struck power lines on February 10, 2003, in N27TV. According to the aircraft incident report completed by the pilot, the purpose of the flight was wildlife control for the U.S. Department of Agriculture. While flying up a ravine, the helicopter contacted power lines connected to an oil well. Subsequently, the pilot successfully landed the helicopter.

AIRCRAFT INFORMATION

The 1983-model Bell 206B white and blue accident helicopter, serial number 3764, was configured for five occupants with two seats in the cockpit and three forward facing rear seats. The helicopter was powered by a 420-shaft horsepower Allison Engine Company 250-C20J turbo shaft engine, serial number CAE270141, and equipped with a two bladed main rotor system, and a two bladed tail rotor. The helicopter was equipped with a wire strike protection system (WSPS) which includes a upper cutter/deflector, a windshield cutter/deflector, and a lower cutter/deflector. Each cutter is equipped with high tensile steel cutting blades.

The helicopter underwent its most recent annual inspection on March 4, 2004, and at the time of the inspection, the airframe had accumulated 6,394.5 total hours. The engine underwent a 100/300 hour inspection on April 16, 2004. At the time of the inspection, the engine had accumulated 6,307.4 total hours and 999.2 hours since major overhaul.

METEOROLOGICAL INFORMATION

At 1953, the Stillwater Airport (SWO) Automated Surface Observing System (ASOS), located approximately 25 nautical miles west of the accident site, reported the wind from 110 degrees at 10 knots, 10 statute miles visibility, sky clear, temperature 78 degrees Fahrenheit, dew point 70 degrees Fahrenheit, and an altimeter setting of 30.03 inches of mercury.

At 2053, the SWO ASOS reported the wind from 170 degrees at 10 knots, 10 statute miles visibility, few clouds at 2,500 feet agl, scattered clouds at 2,900 feet agl, temperature 73 degrees Fahrenheit, dew point 63 degrees Fahrenheit, and an altimeter setting of 30.05 inches of mercury.

The U.S. Naval Observatory reported that the sunset on the day of the accident for Cushing, Oklahoma, was at 2048.

WRECKAGE AND IMPACT INFORMATION

The main wreckage was located at 36 degrees 03:067 minutes North latitude, and 98 degrees 45:142 minutes West longitude. The helicopter wreckage was located in the middle of the Cimarron River in 4 to 5 feet of water approximately 1,500 feet from the power lines. The fuselage came to rest inverted and was 90 percent submerged. The tail boom and main rotor system were separated from the fuselage. The main rotor system came to rest approximately 200 feet forward of the fuselage, and the tail boom came to rest approximately 200 feet aft of the fuselage.

Examination of the accident site revealed the helicopter impacted and severed three power lines approximately 200-300 yards from the main wreckage. According to the power company spokesperson which owned the power lines, the power lines were a 3 AWG (American Wire Gauge) wire, which had a diameter of 0.464" The power lines, which were not marked, crossed the Cimarron River from north to south, and were approximately 30 to 40 feet above the river. At the time of the accident, the river water level was approximately 2-3 feet above normal due to flood stage conditions. The helicopter's direction of flight over the river was established to be from east to west.

The fuselage, main rotor system, and tail boom were recovered out of the river and moved to the north riverbank by the local authorities under the supervision of a Federal Aviation Administration inspector, on June 27, 2004. Preliminary examination of the wreckage by the NTSB IIC revealed the left forward fuselage was crushed, the left aft door was separated, and a portion of the left fuselage structure was destroyed. The transmission cowling was not recovered. The main rotor mast was fractured near the main rotor static-stop contact zone. The fracture surfaces were consistent with a torsional overload failure. Approximately 8 feet of the WHITE blade remained attached to the hub, and approximately 3 feet of the RED main rotor blade remained attached to the hub. The missing blade sections were not recovered. The main rotor hub assembly was intact. The tail boom was separated from the fuselage near the aft cabin attach point. The horizontal stabilizers, tail rotor, and vertical fin remained attached to the tail boom. The helicopter landing gear skids were separated from the fuselage during the water recovery.

The wreckage was recovered to Air Salvage of Dallas, Lancaster, Texas, for further examination.

PATHOLOGICAL INFORMATION

An autopsy was performed on the pilot by the Office of the Chief Medical Examiner, Oklahoma City, Oklahoma, on June 26, 2004. The autopsy report stated the cause of death was drowning. A toxicological test was performed by the FAA Civil Aerospace Medical Institute, Oklahoma City. The test was negative for carbon monoxide, alcohol and drugs.

TEST AND RESEARCH

On July 7, 2004, at the facilities of Air Salvage of Dallas, the wreckage was examined by the NTSB IIC, and representatives from airframe and engine manufacturers. Examination of the wreckage revealed the upper 3-inches of the windshield-mounted wire cutter was exposed, and the remaining windshield-mounted wire cutter was covered with a protective coating. The protective coating of the forward portion of the lower jaw of the upper wire cutter was rubbed away. No evidence of wire contact with the inside jaws of the upper wire cutter was noted. No evidence of wire contact was noted on the lower wire cutter. The forward landing gear cross tube was fractured inboard of the left front mounting saddle. No evidence of wire contact was noted on the landing gear skid assembly. No evidence of wire contact was noted on the main rotor blades.

Flight control continuity was established from the cyclic and collective to the control tubes in the "broom closet." The control tubes in the "broom closet" were separated near the cabin roof; the separations were consistent with overload failure. The cyclic control servos were actuated by hand, and the collective servo actuator was bent and jammed. The swash plate was intact and functioned when moved by hand. The WHITE main rotor blade pitch link tube was fractured at its lower end and the RED main rotor blade pitch link tube was fractured at its upper end; the fractures were consistent with overload failure. The pitch link tubes displayed scratches and scoring. Control continuity was established from the fracture point of the tail boom to the tail rotor assembly. The tail rotor hub and blades were intact and remained attached to the 90-degree gearbox. The tail rotor pitch-change mechanism functioned and the 90-degree gearbox was free to rotate. Drive continuity was established from the tail boom fracture to the tail rotor assembly.

The main transmission remained attached to the airframe. The main drive shaft was separated at both ends. Rotational scoring was noted on the main drive shaft. The main rotor mast, which remained attached to the transmission exhibited paint scratches and scoring. The fuel cell was intact and remained in the aft fuselage structure. The airframe fuel filter was removed and was full of fluid consistent with fuel.

The engine remained partially attached to the airframe. One left engine mount was bent, the other one was fractured, and the right engine mounts were intact. The first and second compressor stages were intact and contained sand and airframe debris, and the compressor would not rotate. The gas producer turbine (N1) would not rotate, and the free turbine (N2) would rotate with roughness. Continuity was established from N2 to the power turbine output. The power turbine governor pointer was observed in the MAX position. The throttle pointer on the fuel control was observed in the full open position and the fuel flow valve was in the low setting. The fire shield to fuel nozzle fuel line was fractured at the nozzle, and the fuel nozzle was partially separated from the combustion case. The engine was removed for further examination.

On September 8, 2004, at the facilities of Rolls Royce, the engine was examined and disassembled by the NTSB IIC and a representative of the engine manufacturer. The examination and disassembly revealed the compressor assembly contained sand and silt deposits. The compressor assembly rotated when removed from the accessory gearbox. The compressor blades were not damaged and contained sand deposits. The impeller and compressor shroud displayed a 360 degree rub and metal transfer. The fourth stage turbine nozzle displayed a heavy rub in the 1 to 10 o'clock area and a light rub in the remaining area of the nozzle. The accessory gearbox contained water, sand, and corrosion, and the gearbox would not rotate. The compressor, accessory gearbox, and turbine assembly contained sand and silt throughout. No anomalies were noted that would have precluded engine operation. The fuel control, power turbine governor, and fuel pump were retained for further examination.

On October 13 and 14, 2004, the fuel control, power turbine governor, and fuel pump were examined by the NTSB IIC and representatives from the respective manufacturers. The components were not functionally tested due to debris and contamination found in the components. The components were disassembled and no anomalies were noted that would have precluded operation.

ADDITIONAL INFORMATION

The helicopter was released to the owner's representative on November 10, 2004.

(c) 2009-2011 Lee C. Baker. For informational purposes only.