Event Description
During en route cruise, the airplane's engine began to run rough. Shortly thereafter, a loud bang was heard, and a cylinder penetrated the engine cowling. The pilot performed a forced landing to a field. During the ground roll, one main landing gear struck a hole, causing it to collapse. The airplane then yawed, and the other main landing gear also collapsed.
Examination Findings
Post-accident examination revealed that the number 3 cylinder had pulled away from the engine case. All through bolts and engine case bolts were separated. Additionally, the piston and piston wrist pin were fractured. Oil was found in the engine sump.
Maintenance History
Maintenance records indicated that the cylinders had been removed and replaced 146 hours prior to the occurrence. The mechanic who performed the installation was interviewed by the FAA and found to be knowledgeable on the tightening procedures recommended by Lycoming.