19970917027039A

Observed spinning to ground. Possible lost tail rotor effect. (.19) 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. Witnesses located on property belonging to 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. The sound was described by two witnesses as "swooshing". Witnesses further reported that when they looked up at the helicopter they saw it "spinning" and descending straight down. A video, taken by personnel of Kenneth Copeland ministr stries, shows the helicopter spinning to the right and descending until it passes out of view behind trees. The video does not show the helicopter entering the spin. The helicopter came to rest upright and sustained extensive vertical crushing of the fuselage. The tail boom remained attached to the fuselage and was resting on the ground. Both rear doors departed the aircraft. Both skids separated from the cross tubes and were found approx. 30 feet to either side of the fuselage, respectively. The cross tubes remained attached to the fuselage and were rotated forward 90 degrees. The main rotor system was intact and sustained minor damage. The tail rotor blades and 90 degree gear box remained attached to the tail boom. Both tail rotor blades were bent and displayed chorwise scratches and leading edge gouges. (.4) 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.