What was found
CORROSION-FWD INTERCOSTAL AT AFT DRAIN MAST, FR86-87 STGR 27R-28R. REMOVED AND REPLACED FWD INTERCOSTAL AT AFT DRAIN MAST, FR86-87 STGR 27R-28R REF. EMB SRM 51-40-08. SEE EAMS W/O H6997 SN 422 FOR WORK DETAILS. AIRCRAFT REMAINS IN HEAVY CHECK BNA.