What was found
LEFT FUEL CELL DEVELOPED LEAK DUE TO RUBBING WITH VERTICAL SUPPORTS AT CENTER BEAM STRUCTURE. INSTALLED ANTI-CHAFF TAPE TO ALL VERTICAL STIFFENERS. REPLACED FUEL CELL WITH REPAIRED LEFT CELL. NOTED THAT THE LAST SEVERAL NEWER MANUFACTURED HELICOPTERS LACKED THE ANTI CHAFF TAPE AT INSTALLATION. STARTING AT HELICOPTER S/N 0573E BY THIS OPERATOR. UNSURE WHEN THE CHANGE WAS MADE, BUT ALL OF THE AIRCRAFT WITH LATER S/N`S DEVELOPED LEAKS DUE TO THE SAME CONDITION. AIRCRAFT MANUFACTURE HAS BEEN NOTIFIED BY THE OPERATOR.