What was found
WITH NO PROBLEMS TO 1952 HRS SINCE NEW (TBO1600), THIS ENGINE WAS OVERHAULED IN FEB 99. NOTHING BUT PROBLEMS SINCE. AT FIRST OIL CHANGE, AFTER OVERHAUL (35 HOURS) ABNORMAL METAL SLIVERS FOUND IN OIL FILTER. CONTINUED FLYING. MORE FERROUS METAL AT 2ND OIL CHANGE (70 HOURS); UNACCEPTABLE AMOUNT AT 3RD (100 HOURS). OVERHAULER REPLACED CAMSHAFT AND ALL LIFTERS WITH NEW MFG PARTS. EXACTLY SAME RESULTS AT SAME TIMES AFTER REPLACEMENT, VOLUNTARILY GROUNDED AIRPLANE ON 4 FEB 2002 WAITING MODIFIED CAMSHAFT NEARING STC APPROVAL. UNDERSTAND STC IS LOW PRIORITY. PLEASE EXPEDITE.