What was found
DURING FLIGHT, RECEIVED AN OVERHEAT INDICATION ON THE NR 1 INTEGRATED DRIVE GENERATOR. DISCONNECTED SAME PER THE COCKPIT OPERATING MANUAL. APU STARTED NORMALLY, HOWEVER AFTER APPROXIMATELY 10 MINUTES AN APU AUTO SHUTDOWN OCCURRED. DIVERTED TO RNO WITHOUT FURTHER INCIDENT. REPLACED THE NR 1 INTEGRATED DRIVEN GENERATOR AND FLUSHED THE EXTERNAL COOLING SYSTEM. LEAK, OPERATIONAL AND FUNCTIONAL DISCONNECT CHECKS WERE ALL OK. APU OPERATED NORMALLY ON THE GROUND.