What was found
FOLLOWING INSTALLATION OF FUEL VALVE, A FUEL SMELL WAS NOTICED IN AIRCAFT CABIN. INVESTIGATION REVEALED FUEL LEAKING FROM THE AFT PLUG ADJACENT TO THE FUEL LINE FITTING PORT WHICH IS AFT WHEN VALVE IS INSTALLED. THIS PLUG IS APPARENTLY INSTALLED DURING MANUFACTURE OF THE FUEL VALVE, AND ONLY A CIRCULAR OUTLINE CAN BE DISTINGUISHED. IT IS DIFICULT TO SEE. THE CAUSE OF THIS LEAKAGE IS UNKNOWN, ALTHOUGH THE PLUG SEEMED TO BE TIGHT.