Pilot Reported That While Enroute The Engine Sustained A Partial Loss Of Power

Location: Trojan, South Dakota Accident Number: CEN24LA341
Date & Time: September 7, 2024, 10:30 Local Registration: N95078
Aircraft: Taylorcraft BC12-D Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial) Injuries: 2 None
Flight Conducted Under: Part 91: General aviation - Personal

Analysis: The pilot reported that while enroute the engine sustained a partial loss of power. The pilot attempted to restore engine power by applying carburetor heat, adjusting the mixture, and checking the fuel control valve. The pilot’s troubleshooting efforts were unsuccessful, and the airplane was unable to maintain altitude. The pilot descended into a wooded valley and conducted a forced landing into the treetops. The airplane came to rest inverted and sustained substantial damage to the fuselage and both wings. 

Postaccident examination of the engine revealed that the hold-down nuts on the right magneto were loose, and the magneto could rotate freely by hand. It is likely that the loose magneto detrimentally affected ignition, which resulted in a partial loss of engine power. 

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- The partial loss of engine power due to a loose magneto and subsequent impact with terrain. 

FMI: www.ntsb.gov