NTSB Identification: DEN07LA142.
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Accident occurred Wednesday, August 22, 2007 in Mullinville, KS
Probable Cause Approval Date: 03/31/2008
Aircraft: Bell 206-L4, registration: N1813
Injuries: 2 Serious,1 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot stated that as he was circling the landing zone, the helicopter felt like it was being "pushed to the northeast and began to shutter." Just as a semi truck passed beneath the helicopter, the pilot stated that the helicopter "went limp" and subsequently the low rotor rpm warning horn activated. The pilot leveled the helicopter from a slight bank and lowered the collective, which silenced the low rotor warning, but the pilot stated that the helicopter "still felt real sluggish." After maneuvering the helicopter away from ground personnel, the helicopter lost power again and the low rotor rpm warning activated a second time. The pilot stated that he set up the helicopter in an autorotative profile and remembers flaring just prior to the initial impact. The pilot stated that he did not lose tail rotor effectiveness. Medical personnel onboard the helicopter stated that during the descent, they noticed power lines and thought that "at out current angle of descent we were going to catch the wires." Several witnesses on the ground stated that as the helicopter passed over the semi truck, it lost control and contacted power lines before impacting the ground. Examination of the wreckage revealed wire damage to the main rotor and tail boom, as well as substantial damage to the fuselage. Further examination of the helicopter disclosed no evidence of any preimpact mechanical anomaly. Weather in the area was reported by local authorities as strong gusty winds.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain main rotor rpm resulting in an uncontrolled descent, collision with transmission wires, and a hard landing. A contributing factor was the tranmission wires. Full narrative available
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