What was found
MCN - MAJOR REPAIR - DURING C-17 CHECK THE SKIN WAS FOUND BULGING BETWEEN FASTENERS INSIDE THE FORWARD CARGO COMPARTMENT AT A PREVIOUSLY INSTALLED REPAIR DOUBLER BS 370 TO BS 390, RBL 36. MAINTENANCE REMOVED REPAIR DOUBLER BS 370 TO BS 390, RBL 36 AND FOUND EVIDENCE OF WATER ENTRAPMENT, NO CORROSION. CLEANED AND TREATED SURROUNDING SKIN AREA; FABRICATED A DOUBLER, TRIPLER, AND FILLERS; INSTALLED REPAIR PARTS IAW B737-300 SRM 53-00-01 FIG 229.