PARK CITY, UT, USA
N16733
BELL 206B III
THE COMMERCIAL PLT FLEW A RESCUE TEAM TO A MOUNTAIN AVALANCHE AREA. THE TEAM DEPLANED AND DURING THE UNLOADING PROCEDURE THE HELICOPTER SETTLED BACKWARDS INTO LOOSE SNOW. THE PLT ADDED COLLECTIVE PITCH AND ATTEMPTED TO HOVER. AS THE HELICOPTER LEFT THE GROUND, AN UNCOMMANDED RIGHT SPIN BEGAN. THE PLT PERFORMED A HOVERING AUTOROTATION 30 FEET AWAY FROM THE GROUND PERSONNEL. AT TOUCHDOWN THE TAIL BOOM ENTERED DEEP SNOW AND THE ACFT CAME TO REST NOSE HIGH. THE PLT DISCOVERED THE TAIL ROTOR SHAFT HAD BROKEN FORWARD OF THE TAIL ROTOR GEAR BOX. A POST ACCIDENT INVESTIGATION SHOWED EVIDENCE THAT THE TAIL ROTOR BLADES ENTERED LOOSE SNOW AND WERE SUBJECTED TO RAPID DECELERATION. THE SHAFT HAD SHEARED UNDER APPLIED TORQUE.
THE SELECTION OF AN UNSUITABLE LANDING SITE BY THE PILOT, RESULTING IN TAIL ROTOR CONTACT WITH THE TERRAIN AND SHEARING OF THE TAIL ROTOR DRIVESHAFT.
Source: NTSB Aviation Accident Database
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