What was found
WHILE CLIMBING AFTER TAKEOFF, STATUS MESSAGES "L ENG OH LP 2" AND "L ENG OH LP 2" DISPLAYED AND EICAS MESSAGE "L ENG OH" DISPLAYED. THE CREW SHUT DOWN THE LEFT ENGINE AND RETURNED TO THE AIRPORT. THE AIRPLANE WAS REMOVED FROM SERVICE (GROUNDED) AND THE MESSAGES WERE CLEARED IN ACCORDANCE WITH 767 FIM 31-41. MAINTENANCE PERSONNEL FOUND THE LEFT ENGINE HIGH PRESSURE PNEUMATIC DUCT LEAKING AT THE DUCT TO ENGINE PORT FLANGE. THE CAUSE OF THE LEAK WAS LOOSE AND MISSING FASTENERS. THE FASTENERS WERE INSTALLED AND TIGHTENED.