What was found
APPROX. 2 HOURS INTO FLIGHT FROM DTW TO SNA SYSTEM 1 PUMP 1 FAULT LIGHT ILLUMINATED. CREW FOLLOWED THE ABNORMAL PROCEDURES FOR HYDRAULIC SYSTEM 1 LOW PRESSURE. CREW NOTICE SYSTEM NR 1 QUANTITY BEGINING TO DROP. CREW DIVERTED HOPING TO GET ON THE GROUND BEFORE LOSS OF TOTAL SYSTEM 1 QUANTITY AND PRESSURE. 15 - 20 MINUTES LATER SYSTEM 1 LO QUANTITY ALERT ILLIMINATED. GEAR AND FLAPS WERE LOWERED USING THE ALTERNATE PROCEDURES. AIRCRAFT LANDED AT THE SLN AIRPORT. A MAINTENANCE CREW WAS DISPATCED FROM DTW TO REPAIR THE PROBLEM. THE MAINTENANCE CREW INSPECTED THE LEFT ENGINE FOUND THE NR 1 HYD. PUMP LEAKING AT THE PUMP SPLIT LINE. THE PRESSURE FILTER WAS INSPECTED FOR CONTAIMINATION, NONE WAS FOUND. THE PUMP WAS RE