On September 11, 1993, a Cessna 180 (registration N7541K) operated by Sixty-thirty North was involved in an aviation accident near Cooper Landing, AK. Investigators recorded the probable cause as: The throttle arm was not safetied to the carburetor throttle stop in accordance with the airworthiness directive, and it separated from the carburetor. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a landing attempt, the pilot experienced unresponsive throttle and overshot the runway. While maneuvering for an opposite-direction landing, engine power further dropped, leading to a descent into trees. Examination revealed a separated throttle arm due to missing safetying per an airworthiness directive.
Incident Overview
A pilot encountered a loss of engine power while attempting to land. After reducing power by retarding the throttle, the engine responded but continued to lose power. When the pilot applied throttle, the engine did not respond. The aircraft overshot Runway 03 during the landing attempt. The pilot then initiated a turn to reverse course for a landing on Runway 21. During the turn, the engine lost additional power, causing the airplane to descend and crash into trees.
Examination Findings
Post-accident examination of the airplane revealed that the throttle arm had separated from the carburetor. The investigation determined that the throttle arm was not safetied to the carburetor throttle stop in accordance with the applicable airworthiness directive. The separation of the throttle arm resulted in the loss of throttle control, preventing the pilot from managing engine power effectively.
Probable cause
The throttle arm was not safetied to the carburetor throttle stop in accordance with the airworthiness directive, and it separated from the carburetor.