What was found
AT APPROXIMATELY 0230 EDST, ENG1 WAS STARTED. AFTER STARTING ENG2, LOST HYD SYS NR 2 BEFORE DEPARTURE TO KBUF. CREW REPORTED HEARING A GRINDING NOISE AND THE PILOT REPORTED SEEING THE #2 HYD SYS INDICATION TURN RED WITH AN ASSOCIATED MASTER WARNING INDICATION BEFORE IMMEDIATE SHUTDOWN. NOTED HYD FLUID HAD COVERED RT SIDE OF THE ACFT. ON INSP, DISCOVERED AN O-RING ON INBD PORT PLUG OF THE NR 2 INTEGRATED HYD MODULE HAD BLOWN OUT & CAUSED SUBSEQUENT LOSS OF HYD FLUID IN NR 2 SYSTEM. O-RING REPLACED AND NR 2 HYD SYS SERVICED. GROUND RUN COMPLETED FOR LEAK CHECK & ACFT DEPARTED 1NY2 FOR HOME BASE. ACFT WAS REINSPECTED AND CLEANED ON ARRIVAL. NO FURTHER DEFECTS NOTED. ACFT RETURNED TO SERVICE.