On April 17, 1994, a Bell 47G-3B-1 (registration N304JP) operated by Sundown Helicopters, Inc. was involved in an aviation accident near Yuma, AZ. Investigators recorded the probable cause as: The throttle arm detached from the carburetor throttle body shaft due to the presence of excessive safety wire, which allowed the arm to slip off the shaft. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
A helicopter pilot was forced into an autorotation after the engine decelerated to idle while attempting to clear a line of trees.
What happened
The pilot was performing a swath run when, while pulling up to clear a line of trees, the engine power decelerated to idle. In response to the loss of power, the pilot entered an autorotation. The subsequent hard landing resulted in damage to the aircraft's fuselage and skids. There were no injuries reported in the incident.
The investigation
Postaccident inspection of the engine identified that the throttle arm had detached from the carburetor throttle body shaft. According to the operator, both the arm and the shaft were new components that had been installed by a contract mechanic on February 24, 1994. The investigation noted that an excessive amount of safety wire, approximately two inches in length, was present on the arm, which permitted the component to slip off the shaft.
Probable cause
The throttle arm detached from the carburetor throttle body shaft due to the presence of excessive safety wire, which allowed the arm to slip off the shaft.