SEYMOUR, IN, USA
N132SP
Bell OH-58A
State Police personnel were using the helicopter in connection with an Emergency Response Team (ERT) static drill. The helicopter was hovering about 1 foot above ground level as 4 ERT members (2 on each side) awaited hand signals from the lead member (first) to stabilize & then (second) to board the helicopter. According to the lead member, the first signal was given for each member to grab a strap & place 1 foot on a skid to stabilize (but not board) the helicopter; however, before the second signal was given, the helicopter began quickly moving to the right. The 2 ERT members on the left side were unable 'keep up' with the helicopter as it banked/climbed, and they fell to the ground. Both right side ERT members climbed aboard the helicopter when they were unable to remain clear of its path. The helicopter continued moving right & rolled into a steep bank. It gained about 10 feet of altitude before it entered a descent & crashed. Weight & balance calculations by Bell Helicopter showed that with the weight of 2 ERT members on the right skid (& no weight on the left), the helicopter's lateral center-of-gravity (CG) limit would have been exceeded by 4.3 inches. There was a flight step above & inboard from each skid. With weight of the 2 ERT members on the right step, the CG would have been exceeded by 3.2 inches). Bell reported the pilot would not have been able to maintain lateral control in either case.
HISTORY OF FLIGHT On April 10, 1997, at 1234 eastern standard time, a Bell OH-58A, N132SP, piloted by a commercial pilot, was destroyed when it rolled over during a hover-loading activity on a grassy area between the North ramp and a closed East-West taxiway at Freeman Field, Seymour, Indiana. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 flight was not operating on a flight plan. The pilot and one passenger reported minor injuries, one passenger was seriously injured. Two other passengers reported no injuries. The helicopter was operated by the Indiana State Police. It was part of an Emergency Response Team (ERT) training activity when the accident occurred. Witnesses reported observing the helicopter hovering about 1 foot above ground level on an easterly heading. These witnesses said 4 ERT members stood along side it, two on each side. According to the witnesses, the four ERT members gave their lead person the signal they were ready to board the helicopter. All four ERT members started to grab the helicopter's cabin boarding straps. As they were doing this, they began to step up onto the landing skids. One of the ERT members on the right side said he had one foot resting on the landing skid. He said he had grabbed the boarding strap after receiving the signal to do so from the team leader. The second ERT member could not recall if his foot was on the skid at the time the helicopter began moving to the right. One of the left side ERT members said he was able to grab the boarding strp and rest his foot on the landing skid. The second left side ERT member said the lead member gave the hand signal to "...initially step on the helicopter." He said the helicopter "...immediately started moving South... and it went completely out of my reach." He said, "I couldn't even reach the heliciopter." Witnesses said the 2 ERT members on the helicopter's right side were unable to escape the helicopter's flight path. They said these ERT members boarded onto the skids. The helicopter began a roll to the right and pitchup. The helicopter continued to roll to the right and climb to about 10 feet above ground level. The witnesses reported the climb stopped and the bank angle continued to increase. They said the helicopter descended and its main rotor blades struck the ground followed shortly by its fuselage. The pilot said the helicopter was "...in a stable one-foot hover when the aircraft began to drift laterally to the right." The pilot said he applied corrective controls but the "...drift continued to accelerate until it became uncontrollable." He said the helicopter made an abrupt roll to the right. He said, "I don't know what happened, but I have performed this maneuver numerous times." The pilot did not report any control or powerplant problems before or during the events leading to the accident. PERSONNEL INFORMATION The pilot of N132SP is employed by the State of Indiana as a helicopter pilot. He stated he also currently flies helicopters for the United States Army Air National Guard. He said he had flown the Bell UH-1 and OH-58 series of helicopters for the U.S. Army when he was on active duty and during his Air National Guard duty. His flight experience includes the Sikorsky Blackhawk, McDonnell-Douglas Apache, Messerschmitt-Boelkow, Hughes 500, and Avstar series of helicopters. According to the pilot's NTSB Form 6120.1/2, he has a total pilot-in-command time of 3,341.2 hours in various makes and models of helicopters. He stated he has 263.8 hours pilot-in- command time in the Bell OH-58 series helicopter. AIRCRAFT INFORMATION N132SP was obtained from the U.S. Army Air National Guard on September 11, 1996. The civilian model designation is Bell 206A-1. When obtained by the Indiana State Police, N132SP had a total airframe time of 2,952.8 hours. At the time of the accident, N132SP had a total airframe time of 2,987.1 hours. The helicopter is maintained according to the U.S. Army's phase inspection program. Its last inspection was a 6-month inspection on January 20, 1997. WRECKAGE AND IMPACT INFORMATION N132SP's fuselage was facing 290 degrees' magnetic resting nose down on its right side. The front right portion of the fuselage was crushed inward about 12 inches. Both windshields were broken away from their mounts. The engine floor area was separated at the engine's forward end and buckled upward. The forward half of the engine and transmission fairing were collapsed against the main rotor shaft and control servos. The tailboom was partially separated at the fuselage attach point. It was positioned on a magnetic heading of 175 degrees. The main rotor blades were bent at various angles. One blade was missing a midspan section that was found about 180 feet south of the main wreckage. One rotor blade tip section had separated its blade and was found underneath the helicopter. Control continuity between the main rotor blades and cockpit controls was established. The collective servo extension tube and one pitchlink tube were found separated at the approximate midpoint location. The edges of the fracture surfaces on both rods exhibited shear lips. The left collective servo control tube was fractured aft of its attachment point. The right collective control tube was fractured between its bellcrank and swashplate inner ring. Fracture surfaces on both tubes had shear lips along the edges of the fracture surface. The swashplate sleeve was fractured at the barrel section. The surface of this fracture was grainy in texture and a consistent dull-gray color. One main rotor blade pitch link was fractured. Its surface exhibited the same appearance as the barrel section fracture. The main rotor blade mast was bent aft about 5 degrees. The right-hand horizontal stabilizer was collapsed upward about 90 degrees. It was pushed about 10 degrees aft. About 4 inches of the vertical fin and attached tail stinger had separated from the assembly. The tail rotor blades were intact and one was bent in a "vee" of about 30 degrees. The leading edge and surface's of one blade had chordwise scoring about midway between the tip and blade root. When the tail rotor blades were rotated, the blade with the chordwise scoring matched the severed section of the vertical fin. Dirt smears and buildup were observed on the tail rotor blades tip cap rivets. The tail rotor blade drive shaft exhibited torsional twisting near the tail boom's separated end. The tail rotor blade's pitch change control linkage was fractured at the horizontal tube in the roof tunnel and at the tail boom separation point. The fractures had shear lips and were a dull gray in color. Control continuity between the anti-torque pedals and tail rotor was established. The pilot and co-pilot seats and corresponding seat belt/shoulder harnesses were intact. The flight control's control box on the pilot's collective was partially collapsed. All switches, except the fuel and oil bypass, were found in the "OFF" position. The fuel switch was found in the "ON" position. The oil bypass switch was found in the "AUTO" position. All circuit breakers were found in the "IN" position. ADDITIONAL INFORMATION Each hydraulic servo actuator was tested with a hydraulic mule. The two cyclic servo actuators functioned when the cockpit's cyclic stick was moved. The collective servo control arm was found in the mid-position. When pressure was applied to the collective servo, its control arm (servo arm) began to slowly retract. The servo arm moved toward the cylinder until fully retracted. The collective could be moved without resistance, but the servo arm would not extend. The servo arm was bent about 2 degrees off its axis. A lateral weight and balance was calculated for N132SP by Bell Helicopter. Their calculations show that if the two right side ERT members were partly standing on the helicopter's right landing skid and parallel flight step, the lateral center of gravity would be 3.7 inches beyond the lateral limit. If both members were standing only on the right landing skid the lateral weight and balance limit would be exceeded by 4.3 inches. The calculations and information are appended to this report. The Indiana State Police accident report stated the helicopter was practicing a static drill. The report states, "This is where the helicopter would hover inches above the ground and the troopers, [ERT members], would step on and off the runners of the helicopter. The helicopter was not going to take off, just practice the loading and unloading from the runners." There were no plans to have the helicopter takeoff with the 4 ERT members on board. According to the report, "...the [ERT] training is to grab onto the helicopter if something during the exercise goes wrong... ."
improper action(s) by one or more of the emergency response team members, during a hovering/loading sequence, which resulted in the helicopter's lateral center-of-gravity (CG) limitations to be exceeded. A factor associated with the accident was: the pilot's inability to maintain lateral control of the helicopter, once the lateral CG limits had been exceeded.
Source: NTSB Aviation Accident Database
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