What was found
DURING HEAVY CHECK MAINTENANCE FOUND CORROSION ON CENTER FUSELAGE II LH IB CABIN SEAT TRACK UPPER IB FLANGE BETWEEN FR53 AND FR54. REPLACED CENTER FUSELAGE II LH IB CABIN SEAT TRACK BETWEEN FR43 AND FR59 WITH NEW IAW SRM 51-41-02, 51-42-01, 51-42-02 AND 51-43-04.