What was found
ON CLIMB OUT OF PHX EN ROUTE FOR BOI THE NR 1 GENERATOR TEMPERATURE WENT INTO THE YELLOW FOLLOWED BY A GENERATOR HIGH TEMPERATURE LIGHT, ATTEMPT APU START WITH NO SUCCESS. FOLLOWED QUICK REFERENCE HANDBOOK AND DISCONNECTED THE NR 1 GENERATOR, TURNED BACK TO PHX AND LANDED WITHOUT FURTHER EVENT. MAINTENANCE REMOVED AND REPLACED THE NR 1 CONSTANT SPEED DRIVE IAW T/C R5M24003, AND REPLACED GARLOC SEAL IAW BMM 72-61-00, PG. 5, STEP 5B. OPERATIONAL AND LEAK CHECKS WERE GOOD. VENDORS FUNCTIONAL CHECK OF CSD S/N 14890 CONFIRMED FAILURE OF UNIT. UNIT WAS FOUND LEAKING FROM INPUT CARBON SEAL DUE A WORN INPUT BEARING AND SEAL RETAINER, LOSS OF OIL CAUSED HIGH TEMPERATURE INDICATION. UNIT WAS OVERHAULED.