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Main Rotor Hub Failure During Helicopter Aerial Application Flight (N67139)

Ulysess, KS, US

On July 23, 1987, a Hiller 12E (registration N67139) operated by Tri Rotor Spray was involved in an aviation accident near Ulysess, KS. No fatalities were reported. Investigators recorded the probable cause as: The pilot stated that the linkage pin that goes through the mast and pitch change mechanism was not aligned causing the failure. 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 conducting aerial application experienced a main rotor hub failure shortly after takeoff. The pilot reported a misaligned linkage pin caused the failure, leading to an uncontrolled descent and substantial damage.

Incident Overview

During an aerial application operation, a helicopter sustained a main rotor system hub failure. The pilot in command (PIC) reported that the complete rotor head, blades, and paddles had just been reinstalled. After a flight of less than one mile, the failure occurred, rendering the PIC unable to control the aircraft. An uncontrolled descent followed, and the helicopter struck the terrain.

Damage and Injuries

The helicopter was substantially damaged. The PIC suffered minor injuries.

Pilot Statement

The PIC stated that the linkage pin that goes through the mast and pitch change mechanism was not aligned, causing the failure.

Conclusion

The investigation determined that the main rotor hub failure resulted from a misaligned linkage pin. No other causal factors were identified.

Probable cause

The pilot stated that the linkage pin that goes through the mast and pitch change mechanism was not aligned causing the failure.
Maintenance error

Frequently asked questions

What happened in the 23 Jul 1987 Hiller 12E accident near Ulysess, KS?

A helicopter conducting aerial application experienced a main rotor hub failure shortly after takeoff. The pilot reported a misaligned linkage pin caused the failure, leading to an uncontrolled descent and substantial damage.

Were there any fatalities in the 23 Jul 1987 Hiller 12E accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 23 Jul 1987 involved a Hiller 12E, registration N67139, operated by Tri Rotor Spray, at Ulysess, KS.

What was the probable cause of the accident?

The pilot stated that the linkage pin that goes through the mast and pitch change mechanism was not aligned causing the failure.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X31614. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.