What was found
DURING TRANSIT CHECK, A FUEL LEAK WAS DETECTED NEAR APU FUEL FEED LINE DRAIN. APU WAS TURNED OFF, HOWEVER THE LEAK CONTINUED, THE FUEL PUMP WAS TURNED OFF AND LEAK DISAPPEARED. LINE WAS CHECKED BUT NO DAMAGE WAS FOUND. THE APU FUEL FEED VALVE WAS DISCONNECTED AND NO LEAKS WERE DETECTED. APU WAS DEFERRED BY MEL, AND REPLACED IAW MM, AND AN O-RING OF DRAIN TUBE WAS CHANGED IAW MM.