RUSSELL, MA, USA
N163B
BELL 47D1
THE BELL 47D1 WAS ON A SOLO X-COUNTRY FLIGHT WITH A COMMERCIAL RATED (NON-ROTORCRAFT RATED) PILOT WHO WAS WORKING ON HIS ROTORCRAFT RATING. THE HELICOPTER CRASHED IN A WOODED AREA WITH DEBRIS SPREAD ALONG THE FLIGHT PATH FOR OVER 1/4 MILE. POST CRASH EXAMINATION SHOWED THAT ONE STABILIZER BAR WAS MISSING FROM THE ROTOR HEAD AND HAD FAILED OPPOSITE THE DIRECTION OF ROTATION. THE STABILIZER BAR WAS NOT RECOVERED. THERE WAS EVIDENCE OF BLADE FLAPPING AND LOW ROTOR RPM CONDITIONS. NO EVIDENCE OF A FAILURE ON THE FLIGHT CONTROL SYSTEM, OTHER THAN THE MISSING STABILIZER CONTROL BAR WAS FOUND. NO EVIDENCE OF A ENGINE FAILURE WAS NOTED, ALTHOUGH CONDITIONS WERE PRESENT FOR THE FORMATION OF CARBURETOR ICE.
A PILOT INDUCED LOW ROTOR RPM CONDITION, FOLLOWED BY BLADE FLAPPING AS THE MAIN ROTOR BLADE CONTACTED THE TAIL OF THE HELICOPTER.
Source: NTSB Aviation Accident Database
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