As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSTALL NEW TCM CYLINDER AND VALVE ASSY USED SA 631475 PISTON DUE TO WEIGHT DIFFERENCE (TO BALANCE PISTON SET). INSTALL TCM RING SET. FLEW 228.1 HOURS. REMOVE CYL DUE TO ENG MISSING. FOUND TOP OF PISTON AND 1ST RING GLAND BROKEN. TOP 2 RINGS BROKEN. REASON UNKNOWN.