NEWARK, TX, USA
N149SD
Bell OH-58A
The helicopter collided with the ground after it descended from level flight in a right rotating turn. According to witnesses, the helicopter landed and tookoff after a few minutes on the ground. The helicopter circled the airport and was headed upwind about 500 feet above the ground when it pitched up, 'hovered for an instant' and descended to the ground. Examination of the helicopter did not disclose evidence of mechanical malfunction. The filament of the low rotor rpm warning light bulb was stretched, which was indicative that it was on at the time of impact. Acoustic analysis of a video tape recording of the accident revealed the rotor rpm during the descent was 80 percent (normal operating range 90-107 percent). According to the helicopter manufacturer, under the given conditions, at a gross weight of 3,250 pounds, and a height of 500 feet, a hover out of ground effect can be accomplished. The estimated gross weight of the helicopter was 2,750 pounds.
HISTORY OF FLIGHT On September 17, 1997, approximately 0945 central daylight time, a military surplus Bell OH-58A helicopter, N149SD, registered to and operated by the Tarrant County Sheriff's Department (TCSD), was destroyed when it impacted the ground in an uncontrolled descent at Kenneth Copeland Airport near Newark, Texas. The commercial pilot and the observer, who were both employed as peace officers by the TCSD, received fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the public use flight that originated from Fort Worth Meacham International Airport in Fort Worth, Texas, at 0910. The TCSD stated on the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that the flight was "a surv[eillance] mission of suspected criminal activity" in the vicinity of Copeland Airport and "apparently the pilot elected to use the runways for either training in the traffic pattern or to wait there until the next pass on the suspected area." Three witnesses, who were in a pickup truck driving to their work site on the west side of Copeland Airport, reported observing the helicopter "sitting idling" or "hovering" at the south end of runway 17-35. They watched the helicopter for a few minutes and then observed it takeoff to the south and turn left. The witnesses then drove north to a tank battery located "about the midpoint of the runway and a couple of hundred feet west of the runway." After getting out of the truck, two of the witnesses again began to watch the helicopter which had circled the airport and was now north of them heading south over the runway. One of the witnesses at the tank battery estimated the helicopter was at an altitude of "about 300 feet" agl when the nose "pitched up vertically" to the point where the "rotor blade was perpendicular to the ground." He stated that the helicopter then rolled from side to side, made two or three "gyrations," leveled off and began rotating around its center axis. He continued to watch the helicopter, which stayed level and descended rapidly, until he lost sight of it behind trees. Another witness at the tank battery stated that "the front end of the helicopter went straight up in the air." He further stated that the nose went down and the tail went up "a couple of times," then the helicopter leveled out and went into a spin. The witness reported that as the helicopter spun, the main rotor blades were "not too blurry," as though they were turning slower than normal. A witness, who was working at a gas well site located on the north side of the airport, reported that the helicopter flew directly over him from north to south. He estimated the helicopter was at an altitude of "500 to 600 feet" agl and stated that it was "going at a pretty good speed". The helicopter traveled "200 to 300 yards" south of his position and "made a 180 degree turn and faced back to the north." He stated that the helicopter "stopped for a second / hovered for an instant," and he heard a "little pop." He further stated that the helicopter then began to rotate and to descend. A witness, who was riding a motorcycle near the intersection of runways 12-30 and 17-35, looked up at the helicopter when he heard the frequency of the sound it was making decrease "rapidly." He observed "the body of the helicopter rotating below the main rotor." He stopped the motorcycle and continued to watch the helicopter, which he estimated to be "about 300 to 400 feet" agl. He stated that the helicopter was spinning and coming straight down with no forward motion. He further stated that he heard the whine of the engine running, but "it seemed to be at low power, as if the helicopter were idling on the ground." The witness observed the helicopter impact the ground and reported that it "hit the ground flat" and bounced. He heard no sound of the engine running after the impact; however, he watched the main rotor continue to turn for about 2 minutes. Witnesses, who were located in the parking lot of the Child Learning Center operated by Kenneth Copeland Ministries, reported having heard and seen the helicopter flying in the vicinity of the airport prior to the accident. They stated that a change in sound coming from the helicopter drew their attention to it, and when they looked up at the helicopter, they saw it spinning and descending straight down. A video, taken by personnel of Kenneth Copeland Ministries, shows the helicopter spinning to the right and descending vertically until it passes out of view behind trees. The video does not show the helicopter entering the spin. PERSONNEL INFORMATION The pilot occupied the right front seat of the helicopter, and the observer occupied the left front seat. Review of FAA and military records revealed no evidence that the observer had received any flight training. According to FAA records, the pilot held a commercial pilot certificate with helicopter and instrument ratings issued on July 13, 1981. At the time of the accident, he held a second class medical certificate issued on March 31, 1997, with no limitations. According to TCSD personnel, the pilot obtained the majority of his helicopter flight training and flight time as an officer in the U.S. Army Reserves. He completed military flight training in 1980 and remained active as a military pilot, flying primarily Bell UH-1H (Huey) military helicopters, for approximately 6 years. In 1994, when the TCSD acquired three military surplus Hughes OH-6 helicopters, the pilot began flying again and accumulated approximately 50 hours flight time in the OH-6. The TCSD traded two of the OH-6 helicopters for two OH-58A helicopters in April 1995. In April 1997, the pilot began flying the TCSD OH-58A helicopters. A request was made by the NTSB investigator-in-charge (IIC) to the Department of Defense (DOD) for information on the pilot's military flight training and experience. According to the DOD, a search of records at the U.S. Army Reserve Personnel Center, St. Louis, Missouri, was unsuccessful in locating a complete military service record for the pilot. Microfiche copies of an incomplete record indicated that the pilot completed the Officer Rotary Wing Aviator Course, Class 80-26, at Fort Rucker, Alabama, on December 17, 1980. No records detailing the pilot's military flight hours were found on the microfiche. Records provided by Bell Helicopter showed that in August 1997, the pilot successfully completed a Bell 206 Transition Course at the Bell Helicopter Customer Training Academy in Fort Worth, Texas. (The Bell 206 is the civilian version of the Bell OH-58.) On the course registration form, the pilot indicated that he had accumulated 2,400 hours of helicopter flight time of which 25 hours were in the last 6 months. He reported that he had flown the following models of helicopters: UH-1H, OH-6, and OH-58. The course flight records indicated that between August 5 and 8, 1997, the pilot received a total of 4.8 hours dual instruction during three flights in Bell 206B helicopters. During a personal interview conducted by the IIC, the pilot's flight instructor for all three flights reported that the pilot was apprehensive when the training began, but at the end of the three sessions was flying "like a 2,000 hour pilot." According to the instructor, the training did not include demonstrations of settling with power or loss of tail rotor effectiveness. An out of ground effect hover and a deceleration from cruise speed to 60 knots and back to cruise speed were demonstrated by the instructor, but not practiced by the pilot. Quick stops (decelerations to a hover) from a speed of 40 knots at an altitude of 30 feet agl were practiced by the pilot during the training. Records provided by the TCSD indicated that the pilot had flown N149SD a total of 8.7 hours prior to the accident flight. The records indicated that the pilot had flown N642SD, the other OH-58A helicopter owned and operated by the TCSD, a total of 10.9 hours. Based on these records and the Bell course records, the pilot's total time in the accident make and model helicopter (OH-58/Bell 206) was calculated to be 25 hours with 22 of these hours flown in the 90 days preceding the accident. AIRCRAFT INFORMATION According to Bell Helicopter, the aircraft was manufactured on December 29, 1970, and delivered to the U.S. Army on January 25, 1971. The last entry found in the military maintenance records was dated November 2, 1994, and indicated the helicopter had accumulated 3,637 flight hours. TCSD records indicated they had flown the helicopter 61 hours since acquiring it in April 1995. Based on the preceding information, the helicopter's total airframe time at the beginning of the accident flight was calculated to be 3,698 hours. The helicopter was powered by a 420 horsepower turboshaft Allison T63-A720 engine, S/N AE-405542. The military maintenance records indicated the engine was installed new on February 12, 1991. Total engine operating time at the beginning of the accident flight was calculated to be 553 hours. Review of the helicopter's maintenance records by the IIC did not reveal evidence of any uncorrected maintenance discrepancies. The helicopter's gross weight at the time of the accident was estimated by the IIC at 2,750 pounds. Military performance data provided by Bell Helicopter indicated that the helicopter was capable of hovering out of ground effect, at its maximum gross weight of 3,200 pounds, at a height of 500 feet over Copeland Airport, given the weather conditions as reported in the Meteorological Information section of this report. METEOROLOGICAL INFORMATION At 0953, the reported weather conditions at Alliance Airport in Fort Worth, Texas, located 8 nautical miles east of the accident site, were wind from 190 degrees at 15 knots, visibility 10 statute miles, scattered clouds at 12,000 feet, temperature 86 degrees Fahrenheit, dewpoint 70 degrees Fahrenheit, and altimeter setting 29.91 inches of Hg. COMMUNICATIONS Copeland Airport's Aviation Daily Log sheet for September 17, 1997, indicated that a helicopter using the call sign "Sheriff 1" called in on the airport's Unicom frequency at 0936 and was provided with an airport advisory. In addition to a King KLX-135A aviation radio, the helicopter was equipped with a Motorola 800 police radio used for communicating with other TCSD units. According to TCSD records, the police radio in the helicopter was turned on at 0944, but no transmissions were made. AIRPORT INFORMATION Kenneth Copeland Airport (4TA2) is a private use airport that is owned and operated by Kenneth Copeland Ministries. It is located approximately 10 nautical miles north northwest of Fort Worth Meacham Airport, and the field elevation is 688 feet msl. The airport has two paved asphalt runways. Runway 17-35 is 4,800 feet long and 125 feet wide, and runway 12-30 is 3,000 feet long and 80 feet wide. The airport does not have an air traffic control tower. A Unicom radio station provides airport advisory information on frequency 123.075. WRECKAGE AND IMPACT INFORMATION The accident site was located on Kenneth Copeland Airport at the northwest corner of the intersection of runways 17-35 and 12-30. The helicopter came to rest upright on a measured magnetic heading of 210 degrees and sustained extensive vertical crushing of the fuselage. The left and right skids separated from the cross tubes and were found approximately 30 feet to either side of the fuselage, respectively. Both cross tubes remained attached to the fuselage and were rotated forward 90 degrees. The left and right rear doors were torn from the door post hinges and were found about 8 feet and 23 to the left and right of the nose of the helicopter, respectively. The front doors were not installed on the helicopter at the time of the accident. The tail boom remained attached to the fuselage and was resting on the ground. The horizontal stabilizer, vertical stabilizer, and tail rotor gear box remained attached to the tail boom. The tail rotor hub and blade assembly remained intact and attached to the tail rotor gear box. Both tail rotor blades were bent and displayed chordwise scratches and leading edge gouges. The lower portion of the vertical fin was crushed upward and to the right. Damage to the upper portion of the vertical fin was confined to a 6 inch horizontal cut through the leading edge about 2 feet from the top. Three segments of the tail rotor drive shaft were twisted apart: the forward short shaft located beneath the engine, the segment located aft of the horizontal stabilizer, and the segment connected to the tail rotor gear box. Visual examination of the fractures by the IIC revealed no evidence of fatigue cracking. According to the Bell Helicopter metallurgist who examined each fracture, all of the fractures appeared to be the result of overload related to ground impact. The tail rotor moved freely when the tail rotor gear box input shaft was rotated by hand. The magnetic chip detector plug in the tail rotor gear box was clean. Circumferential rub marks were found on the inner surface of the tail rotor drive shaft cover in the area directly above the Thomas coupling disc connecting the drive shaft to the tail rotor gear box. The main rotor hub and blade assembly was intact. One static stop was gouged. No other visible damage to the hub assembly was noted. Damage to the main rotor blades was limited to a puncture on the bottom of each blade corresponding in size and location to the tip of the helicopter's upper wire cutter. Black paint transfers and chordwise scratches were noted on the tips of both blades. The mast was bent approximately 5 degrees. Drive continuity was confirmed by hand rotation from the main rotor head through the transmission to the input quill. The main drive shaft was separated from both the transmission and the engine quills. Several of the individual flexors that make up the "KFLEX" couplings at each end of the shaft were severed. The hole in the firewall through which the main drive shaft passed was enlarged, and the isolation mount cover located behind and below the transmission was severely gouged. Both of the oil lines between the transmission and the freewheeling unit were bent and gouged. The freewheeling assembly operated properly by turning freely in one direction and locking up in the other. Magnetic chip detector plugs in the transmission and the freewheeling unit were clean. Control continuity was confirmed from the main rotor blades through the swashplate to the hydraulic actuators mounted on the roof forward of the transmission. Numerous fractures were found in the cyclic and collective control tubes leading from the hydraulic actuators to the cockpit controls. Visual examination of the fractures by the IIC revealed no evidence of fatigue cracking. According to the Bell Helicopter metallurgist who examined each fracture, all of the fractures appeared to be the result of overload related to ground impact. The security of all bolted connections in the cyclic and collective control systems was verified. Anti-torque control continuity was confirmed from the tail rotor blades through the tail boom to a fracture in the control tube immediately aft of the bellcrank located at the tail boom to fuselage junction. Several other fractures were found in the anti-torque control tubes leading forward from the bellcrank to the pedals in the cockpit. Visual examination of the fractures by the IIC revealed no evidence of fatigue cracking. According to the Bell Helicopter metallurgist who examined each fracture, all of the fractures appeared to be the result of overload related to ground impact. The security of all bolted connections in the anti-torque control system was verified. Dual cockpit controls were installed. The right cyclic stick was fractured, and the left cyclic stick was intact. Visual examination of the fracture in the right cyclic stick by the IIC revealed no evidence of fatigue cracking. According to the Bell metallurgist who also examined the fracture, it appeared to be the result of overload related to ground impact. On the right side of the cockpit, the
The pilot's failure to maintain adequate rotor rpm which resulted in a loss of aircraft control.
Source: NTSB Aviation Accident Database
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