What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO DURING ENGINES START, THE LEFT ENGINE CONTROL LIGHT TURNED ON. MAINTENANCE PERSONNEL PERFORMED BITE TO LEFT EEC IAW FIM 73-10 TASK 801 PROCEDURE, SHOWING THE MESSAGES L REVERSER SLEEVE POSITION SIGNAL OUT OF RANGE; SO THE LEFT ENGINE UPPER LOCKING HYDRAULIC ACTUATOR OF THE SLEEVE REVERSE IAW AMM 78-31-03, TESTED CORRECT. AFTER, DURING PREFLIGHT CHECK, IT WAS DETECTED HYDRAULIC LEAK IN THE MAIN LANDING GEAR PIT. MAINTENANCE PERSONNEL PERFORMED REVISION DETECTING HYDRAULIC LEAK IN THE HYDRAULIC PUMP ACMP SYSTEM A; SO THE HYDRAULIC PUMP ACMP SYSTEM A WAS REPLACED IAW AMM 29-11-21, TESTED CORRECT.