What was found
DURING CLIMB OUT, EXPERIENCED LOSS OF OIL PRESSURE FROM #2 ENGINE, SHUT DOWN #2 ENGINE AND RETURNED TO FIELD WITHOUT FURTHER EVENT. FROM CREW: ON THE LEG FROM CHS TO MEM CLIMBING THROUGH 16,000 FEET FOR 20,000 FEET, CREW FELT A SUDDEN YAW AND WERE ALERTED BY A CAP MESSAGE ALERTING ELEC. CREW'S ATTENTION THEN WENT TO THE NP GAUGE WHICH READ AROUND 20%. TORQUE GAUGE WAS BROUGHT TO FDAU BUG AFTER RISING DUE TO NP DECREASING. CREW PERFORMED APPROPRIATE CHECKLISTS FOR THE ISSUE AND BEGAN TO TURN BACK TO CHS. ENGINE OIL DROPPED BELOW 40PSI AND TRIGGERED LOW ENGINE OIL LIGHT. AT THIS TIME, CREW PERFORMED ENGINE SHUTDOWN CHECKLIST AS WELL AS SINGLE ENGINE PROCEDURES CHECKLIST AS WELL AS DECLARED EMERGENCY. ALL OTHER CHECKLISTS WERE COMPLETED BEFORE LANDING AND TRUCKS WERE ROLLED BEHIND OUT OF PRECAUTION. CREW TAXIED SINGLE ENGINE TO FEDEX RAMP WHERE ENGINE WAS INSPECTED BEFORE SHUTDOWN. MX FOUND BROKEN O-RING ON #2 PCU, R+R PCU, OPS CHECK GOOD