What was found
ETOPS - DURING WALKAROUND, FOUND OIL SCATTERED AROUND #1 ENGINE COWLING AND THRUST REVERSERS. ORIGIN OF OIL SEEMS TO COME FROM AIR OIL HEAT EXCHANGER CORE.// INSPECTED AROUND AOHE NO LEAKS FOUND. RAN ENGINE AT IDLE FOR 5 MINUTES. FOUND OIL LEAKING THROUGHT VANES OF AOHE. 13 FEB 22 2095237. REMOVED AND REPLACED #1 ENGINE AOHE PER AMM 79-21-51. NEED TO CONTINUE FROM STEP 4.C. OK INSTALLATION. 13 FEB 22 2557730 ACCOMPLISHED REMAINING STEPS. OPS AND LEAK CHECK GOOD. COOLER, OIL-AIR OFF 43-7921-9-0001 S/N 41347 ON 43-7921-9-0001 S/N 42410