What was found
WHILE IN HEAVY CHECK - CORROSION ON RIGHT HAND FUSELAGE INTERCOSTAL, UNDERFLOOR AFT OF FRAMES 90 AND 91. REMOVED AND REPLACED RIGHT HAND FUSELAGE INTERCOSTAL, UNDERFLOOR AFT OF FRAMES 90 AND 91. RESTORED SURFACE PROTECTION. REF EMB SRM 51-40-- 08, 51-23-06