What was found
AFTER LEVELING OFF, IN STRAIGHT AND LEVEL FLIGHT. PARAMEDIC IN THE FRONT SEAT I SMELLED FUEL FUMES. RETURNED TO BASE AND FUMES DISSIPATED PRIOR TO LANDING. MECHANIC PERFORMED A GENERAL VISUAL INSPECTION OF BOTH ENGINES, FULL EXTERIOR CHECK FOR EVIDENCE OF FUEL LEAKS, A/C BLOWER MOTOR COMPARTMENT AND FIREWALL SHUT-OFF VALVES IN AFT AVIONICS COMPARTMENT. NO LEAKS OR FUMES NOTED. PERFORMED A GROUND RUN FOR 15 MINUTES WITH VENTILATION SYS ON, NO FUEL FUMES. FLEW ACFT FOR A DURATION OF 25 MINUTES, MIMICKED FLIGHT PROFILE FROM DISCREPANCY FLIGHT WITH DAY PILOT, NO FUMES NOTED. PERFORMED MULTIPLE FLIGHT MANEUVERS IN AN ATTEMPT TO INDUCE A REPEAT FAULT. NO FUMES NOTED. ACFT RETURNED TO SERVICE.