What was found
DURING CRUISE FROM ATL-YUL, AT APPROXIMATELY 29,000 FT THE CREW RECEIVED A HYDRAULIC NR 1 LOW PRESSURE AMBER CAUTION MESSAGE, WITH A PRESSURE DROP FROM 1500 PSI TO ZERO AND A QUANTITY READING OF ZERO. THE CREW COMPLIED WITH QRH PROCEDURES AND THE AIRCRAFT DIVERTED INTO CVG, LANDING SAFELY. THE TOWER ROLLED EMERGENCY VEHICLES AS A PRECAUTIONARY MEASURE. MAINTENANCE REMOVED AND REPLACED THE SYSTEM 1 PUMP PRESSURE TUBE ASSEMBLY, CASE DRAIN TUBE ASSEMBLY, ENGINE HYDRAULIC PUMP, AND FOUR LINE STAND-OFF ISOLATORS. OPS AND LEAK CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)