What was found
(CAN) ON TOP OF DESCENT, CREW ATTEMPTED TO RETARD THE THRUST LEVERS TOWARDS FLIGHT IDLE. THE NR 2 ENGINE CONTROL WOULD NOT MOVE. THE ENGINE WAS SHUTDOWN. POST-FLIGHT INSPECTION FOUND THE NR 2 ENGINE CROSS SHAFT RETAINING NUT HAD BACKED OFF AND RESTRICTED THE MOVEMENT OF THE FUEL CONTROL UNIT PUSH/PULL RODS. THE NUT WAS INSPECTED, REINSTALLED AND SECURED. THE ENGINE WAS RUN-UP SERVICEABLE AND THE AIRCRAFT WAS RETURNED TO SERVICE.