As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS IN THE PATTERN. LOUD BANG FOLLOWED BY SEVERE VIBRATION AND REDUCED POWER. EMERGENCY DECLARED SUCCESSFUL LANDING ACCOMPLISHED. INSPECTED FOUND THAT THE NR 1 CYLINDER TOP HAD SEPARATED AT THE TOP OF THE STEEL SLEEVE. TROUBLESHOOTING AND REPAIR IS ON GOING