What was found
DIAGNOSTICS REPORTS NR 1 ENGINE TREND DATA SHOWS A DELTA EGT INCREASE AND EGTHDM DECREASE. EGT INDICATION ERRORS ARE SUSPECT. GROUNDED - YES. ACCOMPLISHED 78273000, MAINT MESSAGE 77-20871 (T495S4 OUT OF RANGE) ALL LEGS. PRE-CLEAN VALUES: S1 116.22, S2 67.20, S3 74.40, S4 ALL DASHES. ACCOMPLISHED NR 1 ENG EGT CONNECTOR CLEANING REF AMM 77-21-00 S4 CONNECTOR DP1013 REQS TORQUE PLUS SAFETY. PERFORMED T49.5 PROBE AND EGT SYSTEM INSPECTION REF AMM 77-21-01-200-801, FOUND S4 T49.5 PROBE RESISTANCE OUT OF LIMITS. ALL OTHER READINGS WITHIN LIMITS. REMOVED AND REPLACED S4 T49.5 PROBE REF AMM 77-21-01-000-801-F00 AND 77-21-01-400-801-F00. POST-CLEANING VALUES: S1 27.50 S2 19.69 S3 20.10 S4 34.49. CLEARS THE TSR. ETOPS GROUND VERIFICATION SUCCESSFUL.