As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ATTEMPT TO REMOVE CYLINDERS FROM ENGINE CASE, FOUND HOLD DOWN NUTS HAD BEEN OVERTORQUED AND HAD TO BE DRILLED TO BE REMOVED. FOUND MAIN JOURNAL WEB CRACKS IN CYLINDERS NR 4 AND NR 6. SUBMITTER BELIEVES HOLD DOWN NUTS OVERTORQUE TO BE A FACTOR IN CASE CRACKS.