What was found
(AIRCRAFT NOT GROUNDED) (DEFECT DISCOVERED DURING AC HEAVY MX VISIT) NRC 1000-0051: PASSENGER CABIN FLOOR STRUCTURE, FLOOR BEAM BTW FR12 - FR16 AND AT Y-81 FOUND CORRODED. TO BE INVESTIGATED. / PASSENGER CABIN FLOOR STRUCTURE, FLOOR BEAM BTW FR12 - FR16 AND AT Y-81 REPLACED AS PER SRM 51-72-11-911-001 REV.159."