BROOTEN, MN, USA
N4028K
HILLER UH-12E
THE HELICOPTER HAD JUST LIFTED OFF OF THE FLATBED OF A TRUCK WHEN IT STARTED TO SPIN. THE PLT LOWERED THE COLLECTIVE, REDUCED THE POWER & LANDED BESIDE THE TRUCK. DURING TOUCHDOWN, THE MAIN ROTOR BLADES STRUCK THE TRUCK. AN INVESTIGATION REVEALED THAT THE THRUST BEARING, PN 25200-3, IN THE TAIL ROTOR DRIVE WAS INSTALLED BACKWARDS. THIS ALLOWED THE BEVELED DRIVE GEAR TO MOVE FORWARD & BECOME DISENGAGED FROM THE TAIL ROTOR DRIVE GEAR.
Source: NTSB Aviation Accident Database
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