What was found
ENGINE WAS OVERHAULED 7-25-94. SPIRIT AIR VALVES, PN AL19001 AND AL73938, WERE INSTALLED NEW AT THAT TIME. AT 165.0 HOURS TSO, ENGINE RAN ROUGH. INSPECTION REVEALED ALL EXHAUST VALVES, PN AL19001, HAD ABNORMAL WEAR, ONE BEING EXTREME AND VERY NEAR FAILURE. ONLY ONE OF THE VALVE TIPS HAD NOT ERODED THE PART NUMBER AWAY. IT IS MARKED FAA-PMA Z 6 94 AL19001. TOTAL ENGINE FAILURE WAS IMMINENT.