As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING WALK AROUND INSPECTION FOUND OIL STREAKS ON INNER COWLING ON BOTH L/H AND R/H ENG. GROUNDED - YES. C/W IDG AIR/OIL COOLER INSPECTION FOR BOTH #1 AND #2 ENG REF B737-900 24-11-21. FOUND BOTH AFT FINS WITH OIL STAINS ON THE #1 ENGINE AND #2 ENGINE. IDG AIR/OIL COOLER REQ REPLACEMENT. REMOVED AND REPLACED #1 ENGINE AND #2 ENGINE IDG AIR/OIL COOLER B737-900 AMM 24-11-21-000-801 AND AMM 24-11-21-400-801. GROUND VERIFICATION CHECKS GOOD. NO OIL LEAKS NOTED. REPLACED #2 ENG IDG AIR/OIL COOLER.