What was found
WHILE PERFORMING AN OXYGEN SYSTEM FUNCTION CHECK A OXYGEN LEAK WAS DETECTED BETWEEN THE TWO LEFT SIDE PASSENGER OVERHEAD (O2) OUTLETS. A SMALL HOLE WAS FOUND IN (O2) LINE. THIS HOLE WAS A RESULT OF DISSIMILAR METAL CORROSION BETWEEN THE ALUMINUM (O2) LINE AND THE STEEL SUPPORT SPRINGS OF THE PASSENGER VENTILATION DUCT. UPON FURTHER INSPECTION CORROSION HAD DEVELOPED ON OTHER (O2) SUPPLY LINES WERE THESE LINES ARE IN CONTACT WITH THE VENTILATION DUCTS.