What was found
LT ENGINE NR 1 AFT ENG MOUNT HAS PITTED AND CORROSION ON PYLON SHIM. OPENED ACCESS PNL, REMOVED PRECOOLER, REMOVED PLENUM PNL MM 72-20-01. STARTED REMOVAL OF ATTACHING HARDWARE, REMOVED AFT MOUNT AREA VIS INSP UPON SHIM REMOVAL, NO DEFECTS. REMOVED AND REPLACED NR 1 AFT MOUNT PYLON SHIM (IAW 54-42-25). INSTALLED PRECOOLER ON NR 1 PYLON MM 36-11-15, LEAK CHK OK.