What was found
** WHILE AIRCRAFT WAS OUT OF SERVICE FOR HEAVY CHECK** PASSENGER CABIN FWD WET AREA FLOOR STRUCTURE FR16-18 LBL11", SEAT TRACK UPPER FLANGE FOUND CORRODED. REPLACED SEAT TRACK IAW SRM 51-41-01, 51-41-02, 51-43-04 & 51-43-03. AIRCRAFT REMAINS OUT OF SERVICE FOR COMPLETION OF HEAVY CHECK.