As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN REMOVING RT ENGINE NR 4 CYLINDER DUE TO A CRACK, NR 4 PISTON SKIRT FOUND BROKE OFF AT THE 4TH RING LAND. ENGINE THEN REMOVED FROM ACFT FOR TEAR-DOWN INSPECTION. I HAVE FOUND BROKEN PISTON SKIRTS ON THIS PARTICULAR ACFT ON 3 DIFFERENT ENGINES.