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Helicopter Hard Landing After Mechanical Disconnect During Nighttime Chemical Application (N3084G)

Winterhaven, CA, US

On February 10, 2001, a Bell 47-G3B1 (registration N3084G) was involved in an aviation accident near Winterhaven, CA. No fatalities were reported. Investigators recorded the probable cause as: The worn freewheeling inner ring gear allowed a mechanical disconnect between the engine output and the main rotor transmission, resulting in a loss of main rotor speed and the subsequent hard landing. 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 2026-07-04Data APIEditorial standards

A helicopter experienced a mechanical disconnect between the engine and main rotor transmission during a nighttime chemical application, leading to a hard landing that collapsed the skids.

Accident Overview

A helicopter conducting nighttime chemical application on a lettuce field experienced a sudden loss of main rotor speed and executed a hard landing. The pilot had just taken off from a truck platform with 60 gallons of chemicals. At approximately 20 feet above ground level and a forward speed of about 30 miles per hour, a loud screeching sound was heard, followed by a yaw to the left, a rapid decay of rotor rpm, and an increase/overspeed in engine rpm. The helicopter landed hard, collapsing the skids.

Post-Accident Examination

A post-accident examination of the transmission revealed that the outer surface of the free wheeling unit of the inner gear assembly was worn below allowable limits at the roller/gear operating surface. This wear allowed a mechanical disconnect between the engine output and the main rotor transmission, resulting in a loss of main rotor speed and the subsequent hard landing.

Findings

The worn freewheeling inner ring gear caused the mechanical disconnect, leading to the loss of main rotor speed and the hard landing.

Probable cause

The worn freewheeling inner ring gear allowed a mechanical disconnect between the engine output and the main rotor transmission, resulting in a loss of main rotor speed and the subsequent hard landing.
Maintenance error

Frequently asked questions

What happened in the 10 Feb 2001 Bell 47-G3B1 accident near Winterhaven, CA?

A helicopter experienced a mechanical disconnect between the engine and main rotor transmission during a nighttime chemical application, leading to a hard landing that collapsed the skids.

Were there any fatalities in the 10 Feb 2001 Bell 47-G3B1 accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 10 Feb 2001 involved a Bell 47-G3B1, registration N3084G, at Winterhaven, CA.

What was the probable cause of the accident?

The worn freewheeling inner ring gear allowed a mechanical disconnect between the engine output and the main rotor transmission, resulting in a loss of main rotor speed and the subsequent hard landing.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20010307X00557. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.