As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) 7 OF THE 8 STUDS ON NR 2 CYL BROKE ALLOWING THE CYL TO SHIFT CAUSING A VIBRATION. 5 MIN AFTER TAKEOFF THE PILOT NOTED A VIBRATION AND RETURNED FOR A NORMAL LANDING. INSPECTION OF THE LOG BOOK IT WAS NOTED THAT NR2 CYL HAD BEEN REMOVED 375 HRS PRIOR BY THE PREVIOUS OWNER.