What happened
The aircraft sustained damage during a forced landing that followed an unexpected loss of power while cruising. The pilot reported noticing the issue and initially checked the throttle position before advancing it further, but observed no change in engine response. In response to the situation, the pilot declared an emergency on the frequency 121.5. The crew activated the emergency fuel pump; however, they subsequently turned it off because the engine noise suggested it was flooded. The pilot noted that the engine never completely stopped running during this sequence.
The investigation
A thorough examination of the aircraft revealed a critical mechanical failure within the throttle rod assembly. Investigators found that both the brellcrank bearing and the associated bolt were missing from the lower part of the engine assembly, specifically part number 16500161. This disconnection effectively prevented the throttle inputs from reaching the engine.
Findings
Maintenance records indicated that Peninsula Acft Services of Kenai, Alaska, had repositioned the throttle and adjusted the idle and mixture settings just 27 days prior to the accident. The investigation determined that weather was not a factor in this incident. The root cause was traced directly to the mechanical separation within the throttle control system, which rendered the pilot's inputs ineffective.
Safety message
This incident highlights the critical importance of thorough post-maintenance inspections for throttle linkages and fasteners to ensure secure attachment and proper operation.