What was found
FOUND CORROSION ON RT WING SPAR FITTING INSIDE RT FUEL TANK WHILE C/W PHASE 50H INSPECTION AND SB 28-10 FOAM REMOVAL. CLEANED CORROSION TO .040 INCH DEPTH. REMOVED ALL PITTING. CONTRACTED FACTORY. MAJOR REPAIR REQUIRED EVEN THOUGH AREA OF CORROSION WAS LESS THAN 1 SQUARE INCH. STRAP HAD TO BE INSTALLED ON FORWARD FLANGE TO REINFORCE CORRODED AREA. SUBMITTER STATED CAUSE OF CORROSION WAS DUE TO WATER CONTAINED AND TRAPPED IN FOAM COVERING THIS AREA. SUGGEST REMOVING FOAM AND CLOSE INSPECTION OF AREA FOR POWDERY CORROSION.