As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
***CORROSION*** WHILE WORKING U312518 FOUND CORROSION ON BS 1006 FRAME FAIL SAFE CHORD AT TWO LOCATIONS (MARKED). FIRST LOCATION ON LOWER SURFACE OF FAIL SAFE BL 0 TO LBL 2; SECOND LOCATION ON UPPER SURFACE OF FAILSAFE RBL 4 / REMOVED AND REPLACED WITH NEW; FAIL SAFE CHORD BS 1006 FROM STR23L TO STR23R IAW SRM 51-40-02-0G-0 AND BOEING DWG 147A1006 SHEET #36 REV C. 55981U 25MAY21