NTSB Identification: CHI95LA130.
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Accident occurred Wednesday, April 19, 1995 in WINFIELD, KS
Probable Cause Approval Date: 01/16/1996
Aircraft: Brantly Helicopter B-2B, registration: N2198U
Injuries: 2 Uninjured.
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 THE HELICOPTER WAS IN CRUISE FLIGHT AT ABOUT 500 FEET AGL WHEN THE ENGINE RPM '...SUDDENLY AND RAPIDLY INCREASED AS IF THE ENGINE WAS ABRUPTLY UNLOADED...'. THE PILOT SAID HE AUTOROTATED TO A LANDING THAT WAS '...QUITE SMOOTH.' AFTER TOUCHING DOWN THE HELICOPTER SLID AND ROLLED OVER ON ITS RIGHT SIDE. THE PILOT SAID THE TOUCH DOWN FIELD WAS VERY MUDDY. AN EYE WITNESS SAID HE SAW THE HELICOPTER DESCEND VERY RAPIDLY THEN BOUNCE INTO THE AIR. AFTER TOUCHING DOWN A SECOND TIME IT ROLLED OVER ON ITS RIGHT SIDE. THE ON-SCENE INVESTIGATION REVEALED THAT THE HELICOPTER'S OVER-RUNNING CLUTCH HAD FAILED. EXAMINATION OF THE CLUTCH ASSEMBLY REVEALED ITS SPRAGS AND THE INNER AND OUTER RACES WERE WORN BEYOND THE MANUFACTURER'S DESIGN LIMITATIONS. THE WORN PARTS ALLOWED THE CLUTCH TO GO OVER CENTER AND BECOME DISENGAGED.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The total failure of the rotor drive system clutch assembly due to excessive wear of the clutch assembly. A factor in this accident was the soft ground in the emergency landing area. Full narrative available
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