What was found
CREW REPORTED SMELLING FUEL THROUGHOUT THE CABIN APPROX 15 MINUTES INTO FLIGHT. THE ODOR LASTED FOR ABOUT A MINUTE, AND THEN DISAPPEARED. LANDED AT DESTINATION WITHOUT INCIDENT. OPEN BOTH ENGINE COWLINGS AFTER SHUTDOWN TO INSPECT FOR ANY SIGN OF A FUEL LEAK AND FOUND NONE. INSPECTED ACFT FOR SIGNS OF A FUEL LEAK. NO DEFECTS NOTED. REFUELED ACFT WITH NO ISSUE AND RETURNED TO BASE. ON FLIGHT BACK, AGAIN FUEL ODOR DETECTED IN CABIN. MECHANIC INSPECTED ACFT. NO DEFECTS NOTED. LATER FLIGHT CHECK REVEALED NO DEFECTS AND ACFT RETURNED TO SERVICE.