What was found
AIRCRAFT EXPERIENCED A MASSIVE FUEL LEAK INSIDE OF CABIN AREA CAUSING AN INFLIGHT EMERGENCY. DETERMINED FUEL LEAK CAUSED BY CORROSION OF FUEL LINE FROM FIRE WALL TO FUEL PRESSURE INDICATOR. CORROSION CAUSED BY DISSIMILAR METAL OXIDATION WHERE FUEL LINE WAS ROUTED AGAINST STEEL RIBBED DEFROSTER HOSE. ALUMINUM FUEL LINE RUBBED THROUGH OUTER MATERIAL OF DEFROSTER HOSE RESULTING IN ALUMINUM TO STEEL CONTACT. SUSPECT CONDITION EXISTED SINCE MANUFACTURE OF AIRCRAFT. EXTREME HAZARD TO FLIGHT.