Nighttime Accident Involving Unsecured Engine Cylinder (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 #1, #3, #5, and #6 were removed and reinstalled. However, the #5 cylinder was not properly tightened. Multiple individuals worked on the aircraft at different stages of the maintenance. ## Accident Sequence and Findings After departure, the pilot attempted to return to the airport. While on the base leg, the aircraft struck the ground in an inverted and nose-down position. Post-accident examination revealed that the left engine propeller was feathered. The #5 cylinder was found detached from the engine, and the #5 piston, with the connecting rod still attached, was located nearby. ## Maintenance and Regulatory Context The maintenance facility did not have a system in place to communicate what work had been completed. Additionally, the FAA did not require the tracking of work accomplished in facilities other than those operating under 14 CFR Part 121 or 14 CFR Part 145.