What was found
(CAN) WHILE BOARDING, FUEL WAS OBSERVED LEAKING FROM THE RT WING SUMP DRAIN. RESULTING SPILL WAS APPROXIMATELY 5 X 5. BOARDING SUSPENDED. CFR AND MAINTENANCE CALLED OUT TO GATE. HIGH POWER GROUND RUN CARRIED OUT FUEL WETNESS FOUND ON CLAMP CONNECTION REF IPC 28-21-06, FIG 2, ITEM 250. IAW MM 28-21-00-960-801-A REPLACED O-RINGS ON SLEEVE. GROUND RUN, LEAK CHECK SATISFACTORY, ALL PANELS REINSTALLED.