Flight Details
On November 30, 2023, at 1513 central standard time, a Cessna 182C, registration N8880T, was substantially damaged during an accident near Manitowoc, Wisconsin. The pilot and one passenger sustained minor injuries. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
The pilot reported that after about one hour of flight, approximately 6 miles from the Manitowoc County Airport (MTW) at an altitude of 3,000 feet above ground level, the engine lost total power. The pilot turned toward MTW but could not maintain sufficient altitude and chose to execute a forced landing in a wooded area. The aircraft impacted terrain and came to rest inverted. Substantial damage occurred to the fuselage, empennage, and both wings.
Engine Examination
Postaccident examination of the engine revealed that neither magneto produced spark at any spark plug when the engine was rotated by hand using the propeller, or when the magnetos were rotated on a test bench after removal. Upon opening the left magneto housing, signs of oily residue, carbonization, and arcing damage were present between the distributor gear electrode and the distributor block electrodes. The distributor block electrodes had melted and resolidified in proximity to the gear electrode. Oil droplets were observed adhered to the felt strip surrounding the distributor bushing. The rotor exhibited overload damage.
Similar findings were observed in the right magneto: oily residue, carbonization, and arcing damage between the distributor gear electrode and distributor block electrodes. The distributor gear electrode had regions covered by carbonized material, and the distributor block electrodes had melted and resolidified. Oil droplets were present on the felt strip. The rotor showed overload damage consistent with impact forces.
Maintenance Records and Manual Specifications
Continental Aerospace Technologies provided overhaul and assembly instructions for S-20-series magnetos in a Service Support Manual. The manual specified that the felt strip surrounding the distributor bushing should be installed dry and cautioned against lubricating it with distributor block lubricant.
A review of the engine maintenance records indicated that the overhauled engine was installed on October 23, 2021, at a tachometer time of 3,992.9 hours. The engine logbook entries did not mention the installation of the magnetos, but associated paperwork showed that the installed magnetos were overhauled in November 2020. The airplane’s last annual inspection was performed on November 30, 2022, at a tachometer time of 4,081.5 hours.
Atmospheric Conditions
A review of the Carburetor Icing Probability Chart in the Federal Aviation Administration’s Special Airworthiness Information Bulletin CE-09-35, dated June 30, 2009, indicated that the atmospheric conditions at the time of the accident were conducive to the formation of serious icing at cruise power settings.