As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING 100/300 HOUR INSPECTION, FOUND LOW COMPRESSION CYLINDER NR 5. EXHAUST VALVE FOUND TO BE VERY TIGHT IN VALVE GUIDE AND PERFORMED SB388C AND VALVE GUIDE REAMING PROCEDURE, INSPECTED VALVE AND STEM, NO DEFECTS FOUND EXCEPT VALVE GUIDE HAD CARBON BUILD UP. COMPRESSION RETURNED TO NORMAL FOR ENGINE WITH 398.0 HOURS SINCE O/H. COMPANY COOL DOWN POLICY FOR ALL RECIPROCATING ENGINES CHANGED TO FULL 5 MINUTES, ESPECIALLY REQUIRED DUE TO VERY HIGH OAT OVER 95 DEGREES F THIS SUMMER.