What was found
GE DIAGNOSTICS REPORTS NR 2 ENGINE TREND DATA SHOWS A SHIFT IN EGT HOT DAY MARGIN ALL OTHER PARAMETERS NORMAL. EGT INDICATION ERRORS ARE SUSPECT. ACFT GROUNDED. PERFORMED T/C 7873000 AND FOUND FAULT CODE 77-20862 IN THE FAULT HISTORY OF THE NR 2 ENGINE. ACCOMPLISHED EGT INDICATION SYSTEM TROUBLESHOOTING AND CONNECTOR CLEANING IAW AMM 77-21-00-140-801. PERFORMED T49.5 AND EGT SYSTEM INSPECTION IAW AMM 77-21-01-200-801-F00, AND FOUND T49.5 S3 PROBE RESISTANCE OUT OF LIMITS. REMOVED AND REPLACED T49.5 S3 PROBE IAW AMM 77-21-01/401. OPERATIONAL CHECK, RESISTANCE VALUES, AND TEMPERATURE VALUES SATISFACTORY.