What was found
(CAN) WHILE DE-INHIBITING ENGINE FCU, FUEL FOUND LEAKING FROM FIREWALL MOUNTED FUEL FILTER AT BASE OF CANISTER O-RING. FILTER CANISTER REMOVED, NEW FILTER ELEMENT AND O-RING WERE INSTALLED, FILTER ASSY TORQUED IAW AT-802 MM AND PRESSURE TESTED SERVICEABLE. A/C GROUND RUN FOR APPROX 2 HRS OVER ONE WEEK PERIOD. DURING TEST FLT PILOT NOTED FUEL SMELL IN COCKPIT. A/C RETURNED TO BASE. FUEL PRESSURE CHECK ACCOMPLISHED AND FUEL FOUND LEAKING FROM CANISTER TO BASE O-RING LOCATION. FILTER CANISTER SECURING BOLT LOCK WIRE REMOVED AND TORQUE CHECK WAS COMPLETED.