What was found
DURING A ROUTINE INSPECTION, AND WHILE ACCOMPLISHING SB 388, IT WAS DISCOVERED THAT THE VALVE KEY RETAINERS (P/N-17C21191) ON THE EXHAUST VALVE, WERE WORN WHERE THEY CONTACT THE ROTOR CAP. THE WEAR WAS RADIAL, AND THE DEPTH WAS ESTIMATED APPROXIMATELY .020 INCH TO .030 INCH. THERE WAS NO STRONG INDICATION OF WEAR ON THE ROTATOR CAP OR THE GROOVE IN THE VALVE STEM. THESE PARTS WERE REPLACED WITH NEW PARTS.