What was found
IAH - FLIGHT 3038, DURING PREFLIGHT INSPECTION THE CREW REPORTED AN ELECTRICAL BURNING SMELL COMING FROM THE RIGHT RELAY SUPPORT / DISTRIBUTION AREA. MAINTENANCE INSPECTED THE AIRCRAFT AND TIGHTENED VERY LOOSE SCREW ON THE FH ESSENTIAL DC BUS 2 BUS BAR, VERIFIED REMAINING SCREWS TO BE TIGHT, AND REMOVED AND REPLACED TWO RELAYS THAT OVERHEATED DUE TO THE LOOSE CONNECTION. OPERATIONAL CHECKS WERE PERFORMED WITHOUT DEFECT, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.