What was found
AIRCRAFT PERFORMED AN UNSCHEDULED LANDING, DUE TO DRIVE LIGHT OF LT GENERATOR TURNED ON. CAPTAIN PERFORMED ABNORMAL PROCEDURE BUT APU DID NOT START AT FL 400, IT LANDED. MAINTENANCE PERSONNEL VERIFIED APU GENERAL CONDITION AND STARTED IT CORRECTLY; REGARDING LT GENERATOR REPORT, IT WAS DEFERRED IAW MEL PROCEDURE 24-1-3. LATER DURING THE NEXT TRANSIT CHECK AT MEX, THE GENERATOR WAS REPLACED IAW MM 24-11-11, TESTED CORRECT. OVERWEIGHT LANDING INSPECTION WAS PERFORMED IAW MM 05-51-35, NO DAMAGES WERE FOUND.