SINUS N413EK accident near Kingsford, Michigan

Probable cause

The failure of maintenance personnel to properly secure the left carburetor bowl cover, which resulted in an engine fire before takeoff.

NTSB analysis

The pilot stated the engine lost power as he increased power for takeoff. The engine could not be restarted, and the airplane was pushed off the runway onto a taxiway. The pilot allowed the engine to cool and then restarted the engine. The engine ran smoothly for about one minute. When engine power was increased above 4,000 rpm, the engine lost power again. The pilot performed 2 additional engine starts, which also resulted in the engine quitting above 4,000 rpm. The pilot then noticed white smoke emitting from the engine compartment. A fire ensued that resulted in substantial damage to the motorglider.

Postaccident examination of the engine revealed that the right carburetor bowl cover was attached to the carburetor bowl but the carburetor bowl cover retention clip was not in its secure position on the bowl cover. The left carburetor bowl cover was missing and was not recovered; it most likely fell out of the motorglider or was dislodged from the airplane when the fire was being extinguished. An unsecured bowl cover would have allowed fuel to leak onto hot exhaust pipes, resulting in a fire.

Neither carburetor had optional carburetor drip trays installed to mitigate the risk of an engine fire from fuel leaking onto the engine exhaust from the carburetors by directing it away from the exhaust and overboard, which may have prevented the accident.

Engine logbook entries showed that the carburetor bowl covers were removed during recent maintenance. It is likely that the covers were not properly reinstalled during that maintenance.

Text from the NTSB. Open the NTSB docket for CEN23LA165 for the full record.