What was found
DURING HEAVY CHECK MAINTENANCE, IT WAS NOTICED THAT AFT CARGO DOOR CUT OUT, TRIM ATTACH BRACKETS ALONG LWR SILL HAVE SURFACE CORROSION, 4 TOTAL 1 FR 77 + 10.5" 2 FR 78 + 4" , 3 FR 78 + 13", 4 FR 79 + 5". R&R 4 EA ATTACH BRACKETS IAW SRM 51-41-01.