What was found
PILOT EXPERIENCED ROUGH ENGINE ON RUN-UP. PERFORMED COMPRESSION TEST AND FOUND CYLINDER NR 3 HAD ZERO COMPRESSION. UPON REMOVAL OF CYLINDER, FOUND EXHAUST VALVE MISSING APPROX ONE-THIRD OF FACE AREA. FURTHER INSP REVEALED EXCESSIVE WEAR OF GUIDE. OTHER FIVE CYLINDERS HAD EXCESSIVE GUIDE WEAR ALSO. LYCOMING SB NR SB503 ISSUED IN 1992 CALLS FOR REPLACEMENT OF EXHAUST GUIDES WITH NEW P/N LW-19001 FOR ENGINE S/N'S THROUGH L-9293-61A. AFFECTED CYLINDERS FALL OUTSIDE OF THIS S/N RANGE.