What was found
AIRCRAFT RETURNED DURING CLIMB, THE EICAS MESSAGE LT PACK WAS SHOWN AND IT WAS NOT AIR ON LT DUCT. DURING MX REVISION, THE MESSAGES 21-23041 WAS SHOWN, THE FIM 21-51 TASK 803 PROCEDURE WAS PERFORMED; SO THE LT PACK SENSOR WAS REPLACED IAW MM 21-51-03, TESTED CORRECT. MX PERSONNEL PERFORMED OVERWEIGHT LANDING INSPECTION PHASE 1 IAW MM 05-51-35, NO DAMAGES WERE FOUND.