On August 4, 1990, a Hiller UH-12-E (registration N133HA) operated by Morten, Shawn B. was involved in an aviation accident near Garrison, ND. Investigators recorded the probable cause as: The left tail rotor control cable had failed due to overload in an area which had been subject to mechanical abrasion. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During takeoff transition, a helicopter's left antitorque pedal went to the floor, causing uncontrolled rotation. The pilot attempted to land but made uncontrolled contact with terrain. Investigation found the left tail rotor control cable failed due to overload from mechanical abrasion.
Incident
According to the investigation, the incident began during the takeoff transition to forward flight. The pilot observed the left antitorque pedal moving to its full downward position, and simultaneously the helicopter entered an uncontrolled rotation. The pilot maneuvered the helicopter to an area clear of obstacles and attempted to land. The helicopter made uncontrolled contact with the terrain during the landing attempt.
Investigation
Examination following the incident revealed that the left tail rotor control cable had failed. The failure was due to overload at a location where the cable had been subject to mechanical abrasion. The abrasion was present prior to the failure. No other contributing factors were identified in the investigation.
Probable cause
The left tail rotor control cable had failed due to overload in an area which had been subject to mechanical abrasion.