What was found
DIVERTED TO BOI DUE TO LOSS OF APU GENERATOR. THE LEFT GENERATOR WAS LOST ON TAKEOFF. *S/D* APU SHUTDOWN WITH 'APU OIL QTY' MSG. FOUND OIL DRIPPING FROM DRAIN MAST INDICATING A CARBON SEAL DEFECTIVE. GENERATOR COULD NOT STAY ON LINE DUE TO AUTO SHUTDOWN FOR LOW OIL QUANTITY. APU WAS REPLACED. DURING SHOP VISIT, DISASSEMBLY REVEALED A DEFECTIVE CARBON SEAL.