What was found
(CAN) EXPERIENCED NR 1 HYDRAULIC SYSTEM FAILURE, WITH TOTAL LOSS OF FLUID. DURING THE ENROUTE CLIMBOUT. FLIGHT CREW REPORT: WHILE CLIMBING THROUGH FL190 WE RECEIVED A NR 1 ENGINE HYD PUMP CAUTION LIGHT. AFTER ACTIONING THE QRH, A DECISION WAS MADE TO RETURN TO THE AIRPORT, THE STANDBY HYDRAULIC PUMP RESTORED THE PRESSURE. APPROXIMATELY 8 MINUTES LATER, THE FLIGHT CREW NOTICED THERE WAS NO QUANTITY INDICATED IN THE NR 1 SYSTEM AND ENGINE 1 HYD VALVE CLOSED ADVISORY LIGHT ILLUMINATED. THE NR 1 HYD ISO VALVE CAUTION LIGHT WAS OUT. FLIGHT CREW CONCLUDED A NR 1 HYDRAULIC SYS FAILURE. THE ACFT DIVERTED TO ANOTHER AIRPORT AND LANDED UNEVENTFULLY. MAINTENANCE ACTIONS: THE ENGINE DRIVEN PUMP CASE WAS CRACKED WHICH ALLOWED THE HYDRAULIC FLUID TO ESCAPE THE SYSTEM. NR1 EDP REPLACED IAW THE AMM 29-11-01. SIMPLIFIED FLUSHING PROCEDURE COMPLIED WITH IAW 29-10-00, OPC OF NR 1 EDP/LEAK CHECK CARRIED OUT IAW AMM 71-00-00. CHECKED SERVICEABLE. ACFT RETURNED TO SERVICE.