What was found
AIRCRAFT DEPARTED AND DURING CLIMB-OUT AN INDICATION OF XS1 BUS FAILURE. THE CREW COMPLETED THE COCKPIT ABNORMAL CHECK LIST FOR THE ITEM AND RETURNED TO DEPARTURE. MAINTENANCE WAS ADVISED AND MET THE AIRCRAFT UPON ITS RETURN. INVESTIGATION FOUND THE ODOR OF BURNT ELECTRICAL UPON OPENING OF THE AFT EQUIPMENT BAY DOOR. FURTHER INVESTIGATION REVEALED THE NR 1 STATIC INVERTER TO BE FAILED. AN HOUR HAD ELAPSED SINCE THE AIRCRAFT WAS SHUT DOWN AND THE INVERTER WAS STILL HOT TO THE TOUCH AND THE ODOR OF BURNT ELECTRICAL WAS MOST EVIDENT. THE INVERTER WAS REPLACED AND THE AC ELECTRICAL SYSTEM WAS FUNCTION TESTED SERVICEABLE. THE AIRCRAFT WAS RETURNED TO SERVICE.