COMMUTER ACFT HAS OIL PRESSURE FLUCTUATION; THEN WARNING LIGHT. ENG SHUTDOWN. RETURN LAND.

Narrative

APPROX 30 MINS AFTER TKOF; AT FL210 IN CRUISE; R ENG OIL PRESSURE WAS OBSERVED FLUCTUATING +/- 5-10 PSI. OIL PRESSURE HAD BEEN NORMAL UP TO THAT POINT; APPROX 70 PSI. GRADUALLY THE OIL PRESSURE DECREASED TO 25 PSI; WHICH THEN TRIGGERED THE ENG OIL PRESSURE WARNING LIGHT ON THE CWP. PWR WAS REDUCED ON THE R ENG AND A PRECAUTIONARY SHUTDOWN WAS PERFORMED ACCORDING TO EMER CHKLIST. ATC WAS INFORMED OF THE SHUTDOWN AND WE REQUESTED A LOWER ALT AND VECTORS DIRECT TO KCLE. AFTER REQUESTS WERE GRANTED PAX WERE INFORMED OF THE SHUTDOWN AS WELL AS ACR FLT CTL VIA COMMERCIAL RADIO. SINGLE ENG PROCS WERE FOLLOWED FOR THE APCH AND LNDG; WHICH WENT WITHOUT FURTHER INCIDENT. AFTER MAINT INSPECTION; OIL WAS DISCOVERED LEAKING FROM FRONT OF CHIP DETECTOR UNIT. PRIOR TO THIS FLT; AT THE MAINT HANGAR; OIL WAS SEEN COMING OUT 1 OF THE 'PAN DRAINS'; BUT WE WERE TOLD THE ENG HAD BEEN WASHED DOWN AND IT WAS NOTHING MORE THAN THE RUNOFF OF SOLVENT; ETC FROM THIS WASH. ENG HAD JUST BEEN THROUGH A GND RUN AND MECHS TOLD US THERE WERE NO LEAKS.