What aircraft was involved and where did it happen?

The accident on 1985-08-17 involved a Bell 47G-2A, registration N3951U, at Sedalia, MO.

Helicopter Tail Strike Following Loss of Directional Control During Fair Flight (N3951U)

On August 17, 1985, a Bell 47G-2A (registration N3951U) was involved in an aviation accident near Sedalia, MO. Investigators recorded the probable cause as: Failure of the inner bearing (PN 47-620-605-001) of the tail rotor drive, followed by failure of the drive shaft. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

During a fair ride, a helicopter lost directional control after lift-off, leading to a tail strike against a van. Investigation found failure of the tail rotor drive bearing and shaft.

Incident Summary

A pilot was taking two passengers on a helicopter ride at a fair. Immediately after lift-off, the pilot encountered a situation where directional control could not be maintained. The pilot reduced power and landed, but before the helicopter came to rest, its tail struck a van.

Investigation Findings

An investigation revealed that the inner bearing (part number 47-620-605-001) of the tail rotor drive had failed. Subsequently, the drive shaft also failed. The failure of these components resulted in the loss of directional control.

Regulatory Context

Airworthiness Directive 81-04-03, Amendment 39-4029, became effective on February 2, 1981, requiring replacement of the bearing within the next 600 hours of service. The helicopter had accumulated less than 600 hours of service since that date, indicating the bearing was within its compliance interval.

Probable cause

Failure of the inner bearing (PN 47-620-605-001) of the tail rotor drive, followed by failure of the drive shaft.

1985-08-17: Bell 47G-2A (N3951U) — Sedalia, MO