What was found
MCN - MAJOR REPAIR - DURING C-17 CHECK CRACKS WERE FOUND IN THE LOWER RADIUS OF THE AFT CARGO RT OUTBOARD CAP SUPPORT (ZEE ANGLE) AT RBL 21, BS 727C, 727D, 727E, 747, AND 767. MAINTENANCE REMOVED THE OUTBOARD CAP SUPPORT SECTION AT RBL 21, BS 727C TO 767. FABRICATED A NEW CAP SUPPORT SECTION, AND INSTALLED REPAIR IAW B737-300 SRM 51-40-02, PG 3, 38, SRM 51-40-05, PG 4, BMM 51-21-99, PG 701-703, AND DWG 65-47690.