Casualties unknown

Helicopter Engine Failure Following Lift-off (N64789)

LE Grand, CA, US

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.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-22Data APIEditorial standards

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.

What happened

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.

The investigation

Examination of the engine revealed that the turbine rotor was destroyed. Evidence of overspeed and tension overload was found.

Probable cause

The destruction of the turbine rotor due to overspeed and tension overload.

Frequently asked questions

What happened in the 30 Jun 1986 Bell UH-1B accident near LE Grand, CA?

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.

What aircraft was involved and where did it happen?

The accident on 30 Jun 1986 involved a Bell UH-1B, registration N64789, at LE Grand, CA.

What was the probable cause of the accident?

The destruction of the turbine rotor due to overspeed and tension overload.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X33905. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.