What was found
DURING TRANSIT CHECK, CAPTAIN REPORTED THAT APU OIL LIGHT TURNED ON. THE APU REPORT WAS DEFERRED IAW MEL 49-11-1 CAT C AND AIRCRAFT WAS DISPATCHED. LATER, AIRCRAFT RETURNED OF FLIGHT AS A CONSEQUENCE OF DURING CRUISE THE L GEN DRIVE EICAS MESSAGE WAS SHOWN AND THE LEFT GENERATOR SHUT OFF. AIRCRAFT WAS SENT TO THE HANGAR AND DURING OVERNIGHT CHECK, THE LEFT IDG, THE AIR/OIL HEAT EXCHANGER AND THE OIL QUANTITY SWITCH WERE REPLACED IAW MM 24-11-01, MM 79-21-07 AND MM 49-94-04 RESPECTIVELY, TESTED CORRECT. THE OVERWEIGHT INSPECTION WAS PERFORMED IAW MM 05-51-35, ALL CORRECT. DEFERRED REPORT WAS CLOSED.