On December 9, 1989, a Hughes 369HS (registration N9161F) operated by Air Kaui, Inc. was involved in an aviation accident near Waimea, HI. Investigators recorded the probable cause as: Fatigue fracture of the fuel control PC tube due to bending stresses introduced during installation, associated with the tube exceeding the specified required length and being bent to fit by maintenance personnel. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter conducting a sightseeing flight with four passengers suffered an engine power loss and rolled over during autorotation. Examination revealed a fractured fuel control PC tube due to fatigue from bending stresses during installation.
Incident Overview
A certificated air line transport pilot was conducting a helicopter sightseeing flight with four passengers when the engine suddenly lost power. The pilot performed an emergency autorotation to the bottom of a small river bottom. During landing, the helicopter rolled over.
Examination Findings
Examination of the engine revealed that the fuel control PC tube to the power turbine governor had fractured. This fracture caused the engine to go to a flight idle condition. The tube was found to exceed the specified required length of manufacture. During installation, the tube was bent by company maintenance personnel to fit. Metallurgical examination disclosed a fracture due to fatigue near the fuel control end. This fatigue was introduced by bending stresses in the tube.
Probable cause
Fatigue fracture of the fuel control PC tube due to bending stresses introduced during installation, associated with the tube exceeding the specified required length and being bent to fit by maintenance personnel.
What happened in the 9 Dec 1989 Hughes 369HS accident near Waimea, HI?
A helicopter conducting a sightseeing flight with four passengers suffered an engine power loss and rolled over during autorotation. Examination revealed a fractured fuel control PC tube due to fatigue from bending stresses during installation.
What aircraft was involved and where did it happen?
The accident on 9 Dec 1989 involved a Hughes 369HS, registration N9161F, operated by Air Kaui, Inc., at Waimea, HI.
What was the probable cause of the accident?
Fatigue fracture of the fuel control PC tube due to bending stresses introduced during installation, associated with the tube exceeding the specified required length and being bent to fit by maintenance personnel.
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