What was found
MCN - MAJOR REPAIR - DURING C-17 CHECK A .25 INCH CRACK WAS FOUND ON SKIN AT LOWER ROW OF FASTENER HOLES STR 4 RT, BS 431. MAINTENANCE CUTOUT CRACKED SKIN AT STR 4 RT, BETWEEN BS 428 AND BS 432; PERFORMED A HFEC INSPECTION OF CUTOUT TO VERIFY NO CRACKS EXIST; FABRICATED 2 EACH DOUBLERS, 2 EACH FILLERS, 2 EACH INTERNAL DOUBLERS AND A TAPERED FILLER; INSTALLED REPAIR PARTS IAW B737-300 SRM 53-00-01 PG 355 FIG 228.