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Helicopter tail rotor damage during Christmas tree loading operation (N1089D)

Winlock, WA, US

On November 14, 1986, a Hughes 369D (registration N1089D) was involved in an aviation accident near Winlock, WA. Investigators recorded the probable cause as: The pilot's failure to maintain adequate clearance between the long-line sling and the treetops, which resulted in the sling rebounding into the tail rotor and causing gearbox damage. 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 2026-06-20Data APIEditorial standards

A helicopter sustained tail rotor gearbox damage after the long-line sling rebounded into the rotating blades while returning to a pickup area, leading to a hard autorotative landing.

What happened

The pilot was engaged in an aerial logging operation, specifically loading Christmas trees from a farm onto a truck. After releasing a load, the aircraft was en route back to the pickup area when the empty long-line sling made contact with the treetops below. The impact caused the sling to rebound upward, striking the tail rotor assembly and damaging the gearbox. This mechanical failure resulted in a loss of control. The pilot initiated an autorotative landing to manage the emergency, but the helicopter touched down hard.

The investigation

The primary mechanical issue identified was damage to the tail rotor gearbox caused by the rebounding long-line sling. No other mechanical failures were noted prior to the impact event.

Findings

  • Tail rotor gearbox damage sustained from contact with a rebounding sling
  • Loss of control following the mechanical failure
  • Hard landing during autorotation attempt

Probable cause

The pilot's failure to maintain adequate clearance between the long-line sling and the treetops, which resulted in the sling rebounding into the tail rotor and causing gearbox damage.
Loss of control in flight

Frequently asked questions

What happened in the 14 Nov 1986 Hughes 369D accident near Winlock, WA?

A helicopter sustained tail rotor gearbox damage after the long-line sling rebounded into the rotating blades while returning to a pickup area, leading to a hard autorotative landing.

What aircraft was involved and where did it happen?

The accident on 14 Nov 1986 involved a Hughes 369D, registration N1089D, at Winlock, WA.

What was the probable cause of the accident?

The pilot's failure to maintain adequate clearance between the long-line sling and the treetops, which resulted in the sling rebounding into the tail rotor and causing gearbox damage.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X35279. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.