What was found
DIAGNOSTICS REPORTS NR 1 ENGINE TREND DATA SHOWS A SHIFT IN EGT, HOT DAY MARGIN, ALL OTHER PARAMETERS NORMAL. EGT INDICATION ERRORS ARE SUSPECT PRI: 2 ETOPS SIGNIFICANT SYSTEM. GROUNDED - YES. ACCOMPLISHED T49.5 PROBE & EGT SYSTEM INSPECTION AND CLEANING. FOUND T49.5 S4 PROBE OUT OF TOLERANCE. REPLACED T49.5 S4 PROBE. OPS CK GOOD. REF AMM 77-21-00-140-801, AMM 77-21-01-200-801-F00, AMM 77-21-01/401. BEFORE CLEANING T49.5 SENSOR VALUES: T49.5 S1 59.66, S2 32.59, S3 36.91, S4 92.55. AFTER CLEANING T49.5 SENSOR VALUES: T49.5 S1 16.68, S2 12.72, S3 12.64, S4 25.06.