Nighttime Accident Involving Single-Engine Airplane After Maintenance (N600JB)

Incident Overview and Maintenance Background The aircraft departed at night after maintenance work was completed on the left engine. During the maintenance process, cylinders numbered 1, 3, 5, and 6 were removed and reinstalled. However, the number 5 cylinder was not properly tightened. Multiple individuals worked on the aircraft at different stages, and the maintenance facility lacked a system to communicate the status of completed work. Additionally, the FAA did not require tracking of work accomplished in facilities other than those operating under 14 CFR Part 121 or 14 CFR Part 145. ## Accident Sequence and Findings After departure, the pilot attempted to return to the airport. While on the base leg, the aircraft struck the ground inverted and nose down. Post-accident examination revealed that the left engine propeller was found feathered. The number 5 cylinder was found off the engine, and the number 5 piston with the connecting rod still attached was located nearby. ## Probable Cause and Contributing Factors The official investigation determined that the probable cause was the pilot's failure to maintain airspeed during a precautionary landing, which resulted in a loss of control while operating with one engine shut down. An additional cause was identified as improper maintenance procedures that led to the number 5 cylinder not being tightened down. Night conditions were cited as a contributing factor to the accident.