What was found
AFTER TAKEOFF FROM SBN, THE AIRCRAFT CLIMBED TO FL290. SHORTLY AFTER REACHING CRUISE ALTITUDE, THE RIGHT ENGINE OIL PRESSURE WARNING ILLUMINATED FOLLOWED BY A DROP IN OIL PRESSURE ON THE RT OIL PRESSURE GAUGE. THE FLIGHT CREW PERFORMED THE QRH AND REDUCED POWER ON THE ENGINE. SEEING THAT THE OIL PRESSURE CONTINUED TO DROP, THE CAPTAIN ELECTED TO SHUTDOWN THE ENGINE. AN EMERGENCY WAS DECLARED AND AN OTHERWISE UNEVENTFUL APPROACH AND LANDING WAS MADE AT MSP. MAINTENANCE FOUND THAT THE AIRCRAFT HAD A MEL'D NR 2 ENGINE DRIVEN HYDRAULIC PUMP. FURTHER INVESTIGATION REVEALED THAT THE PUMP HAD NOT BEEN PROPERLY MEL'D AT SBN. OIL LOSS WAS THE RESULT OF A MISSING SPLINE PLUG AND O-RING WHICH ARE PART OF THE MEL KI