Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Time Pressure; Situational Awareness; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Aircraft
Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; Flight Crew Inflight Shutdown; Flight Crew Diverted; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Incorrect / Not Installed / Unavailable Part; Equipment / Tooling
During preparation for our flight; all pre-flight items and activities were normal. There were no discrepancies were noted.  We departed ZZZ for ZZZ1. Once in cruise; the Captain and I noticed the oil quantity decreasing. We consulted the QRH for low oil quantity. As the quantity continued to decrease; the Captain called dispatch and maintenance for any guidance or assistance they could give.  The tech told the Captain to follow the QRH.  The Captain and I began discussing engine shutdown and diversion scenarios. The oil level eventually fell to zero. Over a period of time; the oil pressure also began to fall slowly and we now were consulting the low oil pressure and engine shutdown procedures in the QRH.  In the descent to ZZZ airport ; the oil pressure dropped to where the QRH directs engine shutdown. We followed the engine shutdown checklist and [advised the TRACON]. We were vectored for a Visual approach to runway XX. When we transferred to ZZZ1 tower; we were cleared to land. A few miles from landing; ZZZ1 tower advised us that ZZZ2 tower reported possible missing cowlings from our engine. The Captain informed me that he was going to stop on the runway to find out if there was aircraft damage before proceeding to the gate. The landing and rollout were normal and we stopped the aircraft on the runway. After an inspection of the aircraft; the fire commander gave us the all clear to proceed to our gate with rescue personnel following. At the gate and after the jet bridge was brought to the aircraft; we were met by two mechanics. We briefed them on the situation and they went outside to investigate. Once they opened the cowls; I went down to find out if they had any idea what happened. I could see that the inner cowl was covered with oil on the inside; but there was no evidence of oil on the outside of the nacelle and only a little had dripped on the ground. I was told by one of the mechanics that they found an 'oil plug' in the bottom of the inside cowl when they opened the engine cowls. I returned to the cockpit to brief the Captain with the information I acquired on the ramp.
Flight Crew reported a loss of engine oil quantity and a loss of oil pressure caused an inflight shut down of the engine and an ATC guided landing.