On June 30, 1986, a Bell UH-1B (registration N64789) was involved in an aviation accident near LE Grand, CA. Investigators recorded the probable cause as: The destruction of the turbine rotor due to overspeed and tension overload. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter suffered an engine failure shortly after lift-off prior to a spray run, resulting in a ground collision due to turbine rotor destruction from overspeed.
The aircraft experienced an engine failure shortly after lift-off while preparing for a spray run on a nearby field. The engine decelerated to zero, and the aircraft collided with the ground.
Examination of the engine revealed that the turbine rotor was destroyed. Evidence of overspeed and tension overload was found.
The destruction of the turbine rotor due to overspeed and tension overload.