What was found
(CAN) AT FL250 FLIGHT CREW NOTICED THAT THE PTU "GREEN HATCH" WAS FLICKERING ON AND OFF, APPROXIMATELY 15 SECONDS LATER THE NR 2 HYD PUMP CAUTION LIGHT START FLICKER ON AND OFF AND THEN AFTER 30 SECONDS WAS STEADY ON. HYD FLUID START TO DECREASE ON NR 2 SYSTEM, THEN APPROXIMATELY 3 MINUTES LATER THEY NOTICED THAT ALL FLUID HAD BEEN LOST AND THE ASSOCIATED CAUTION LIGHTS ILLUMINATED. FLIGHT CREW DIVERTED TO MAINTENANCE BASE WHERE MAINTENANCE CONFIRMED THE FAULT AND PROCEED TO REPLACE THE NR 2 HYD PUMP AND FLUSH THE SYSTEM. ACFT WAS RELEASE TO SERVICE.