What was found
(CAN) DURING LEAK CHECK AFTER INSTALLATION, A LEAK WAS DISCOVERED AT THE FUEL PUMP TO MFC MATING SURFACE. THE MS9967-016 O-RINGS WERE REPLACED, BUT THE LEAK PERSISTED. CLOSER INVESTIGATION OF THE PUMP MATING SURFACE REVEALED THAT THE O-RING CUTOUTS AT THE OUTLET AND BYPASS RETURN PORTS WERE MACHINED DEEPER THAN A COMPARABLE UNIT. (APPROXIMATELY .005 IN OUT OF TOLERANCE). ANOTHER FUEL PUMP WAS FITTED AND THE AIRCRAFT WAS RETURNED TO SERVICE. THE SUBJECT PUMP WAS RETURNED TO THE OVERHAUL FACILITY. ENGINE CHX.