Amateur-built BOT JOURNEY N814B accident near Ocean Isle Beach, North Carolina

Probable cause

Maintenance personnel’s failure to identify and remediate a buildup of oxides in one of the engine’s carburetors, which resulted in the seizure of the carburetor’s piston slide and a subsequent total loss of engine power during initial climb.

NTSB analysis

The pilot, who was also a repairman who had recently completed maintenance on the airplane, reported that the recently installed engine had been running poorly and had previously experienced a loss of power during ground operations. While troubleshooting, the pilot discovered that the carburetor floats were improperly installed, so he replaced the carburetor floats and spark plugs. Maintenance records indicated that the carburetors were repaired three days before the accident, and the engine was reported to have operated satisfactorily following the maintenance. Additional ground runs and high-speed taxi tests were completed without reported anomalies.

On the day of the accident, the pilot planned to perform a functional test flight and reported that all engine indications were normal during the takeoff roll and initial climb. While climbing through about 200 ft msl, the engine lost power without warning. The pilot initiated a left turn in an attempt to remain near the airport and maintain glide speed; however, the airplane descended into trees. The pilot was seriously injured and the airplane’s fuselage was substantially damaged during the accident sequence.

A postaccident examination of the engine revealed continuity throughout the crankshaft and valve train, normal compression on all cylinders, and no evidence of lubrication deficiencies, overheating, detonation, preignition, or other internal mechanical malfunctions. Examination of the carburetor for the engine’s number 2 and 4 cylinders revealed that its piston slide had seized due to a buildup of oxides in the chamber top cavity where the piston slide shank moved. No contamination was observed within the carburetor, and no other anomalies were revealed during the examination of the engine or fuel system. The engine manufacturer stated that a seized piston slide could result in reduced engine performance, rough engine operation, or improper fuel delivery to the cylinders. Given this information, it is likely that oxide buildup in the carburetor was not identified and remediated during the recent maintenance of the carburetors that had occurred just before the accident, which resulted in the seizure of its piston slide, and the subsequent total loss of engine power during the accident flight.

Text from the NTSB. Open the NTSB docket for ERA25LA062 for the full record.