What was found
PILOT NOTICED RT ENGINE WAS RUNNING ROUGH. SHUT DOWN ENGINE, DURING INSPECTION FOUND THAT NR5 CYLINDER WAS COLD, WITH COMPRESSION TEST, RESULTS WAS 0/80. FOUND EXHST STUD AND NUT MISSING, ALSO REVEALED BURN MARKS FROM EXHST AND MANY CRACKS AROUND EXHST PORT AND SPK PLUG HOLE. RMVD EXHST SYSTM AND CYL, EXHST VLV WAS SITTING ON TOP OF THE SEAT WITH LOOSE SEAT BECAUSE OF CRACKS THROUGH SEAT AREA. POOR COND. OF CYL PRIOR TO O/H . EXTENT OF RECOND REQUIRED TO REPAIR PREVIOUS DAMAGE EVIDENT BY WELD AROUND SPK PLUG HOLES AND PORTS WAS TO MUCH FOR CYLINDER IN THIS COND. DAMAGE AROUND EXHST PORT., IMPROPER INSTALL OF STUD OR REPAIR OF HOLES ARE WHERE CRKS STARTED THEN EXHST BURN THRU.