What was found
FLT NR 603 - ATL-LGB - CREW REPORTED, THAT NR 1 ENGINE GREEN HYD PUMP 'MI' WENT AMBER SHORTLY BEFORE TOP OF DESCENT. NR 1 PUMP WAS SET TO DUMP. PRESSURE AND QTY NORMAL. APPROX 5 MINUTES LATER, QTY WENT TO ZERO. LANDED LGB SAFELY. AIRCRAFT TOWED TO TERMINAL FROM RUNWAY. MAINTENANCE REPLACED NR 1 ENGINE HYD GREEN PUMP, CASE DRAIN FILTER AND FLUSHED OUT THE HYD SYSTEM. OPERATIONAL CHECK NORMAL. AIRCRAFT RELEASED FOR SERVICE. (M)