What was found
CLE - FLT 4054 - CREW REPORTED THAT DURING CRUISE FLIGHT AT 21,000 FEET THE GREEN SYSTEM HYDRAULIC MAIN PUMP LOW PRESSURE LIGHT ILLUMINATED INTERMITTENTLY AND THE ELECTRIC PUMP CAME ON INTERMITTENTLY. THE AIRCRAFT RETURNED TO FIELD. MAINTENANCE INSPECTED THE HYDRAULIC SYSTEM AND THEN REMOVED AND REPLACED THE LEFT ENGINE DRIVE HYDRAULIC PUMP IAW EMB120MM 29-10-03. OPERATIONAL AND LEAKS CHECKS WERE GOOD. AIRCRAFT RETURN TO SERVICE. (M)