Date: 201807
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Cruise
Airspace: Class B ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Oil Distribution
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP)
Second reporter function: Captain; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed As Precaution; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Inflight Shutdown
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: It was suspected that the loss of engine oil could have occurred during the replacement of GEN #1. During our preflight; the captain and I noted 10 qts and 11 qts of oil on each respective engine. My captain and I were operating flight to ZZZ. The flight was operated in VMC conditions and took off without any issues. In the last bit of our cruise phase of flight; I happened to notice that the Engine 1 Oil Pressure was slowly dropping. We opened the oil page to find that our oil quantity was dropping as well. We decided to reduce thrust on Engine 1 to idle and consult the QRH. At the time we opened the checklist to the Oil Low Pres Checklist the oil pressure indication was in the red range. In addition; ATC was already stepping us down on the arrival into ZZZ. After running the appropriate checklists; we advised ATC that we would continue to ZZZ as we could see it in the distance and the aircraft was under positive control and no immediate danger was present. Additionally; our decision to continue to ZZZ was based on runway length availability; where we were in the arrival phase of flight; size and resources. Since we were without ACARS; we appropriately divided our duties to prepare the airplane for landing; notify the company; and gather performance data. In such a short amount of time; we were able to accomplish all our tasks without any issues. ATC was extremely accommodating and cleared traffic so we could head directly towards the field. The flight landed safely on [Runway] XXL in ZZZ without any issues and we were met by CFR. They escorted us to the gate. Overall the event was textbook and went extremely smooth.


Second narrative: This flight was the aircraft's first flight of the day. During preflight; I noted both engines having 10 qts and 11 qts of oil respectively. In cruise; oil quantity on the affected engine dropped to 3 qts. At the gate; we noted 2 qts on the affected engine; #1.The logbook showed that Maintenance had recently done a generator change on this engine. The post-flight inspection revealed a significant amount of oil on the bottom of the cowling apparently emanating from the generator area.Departed ZZZ on schedule. VMC conditions. Normal departure and climb out up to cruise altitude.Approximately 130 miles from ZZZ; we recognized the #1 Engine oil pressure had dropped into the amber range. We immediately reduced thrust on that engine to idle and consulted the QRH. By the time we located the Oil Low Press Checklist; the oil pressure had dropped into the red range. We then performed a Precautionary Engine Shutdown Procedure as per the checklist.We notified Center Control of our situation and requested lower. We informed ATC of our intent to continue to ZZZ; requested emergency vehicles standing by; and gave souls on board and remaining fuel.At the time of the emergency; ATC had already begun stepping us down in altitude from our assigned cruise altitude of FL260. We were could see [the city] in the distance. We were within 30 minutes of ZZZ. The First Officer and I considered diverting but agreed that continuing on to ZZZ was the safest; most prudent course of action as the weather was VMC with light winds; the aircraft was in no immediate danger; and the situation was under control. ATC moved aircraft out of the way; assigned us direct ZZZ and gave us pilot's discretion to 10;000 [feet]. The First Officer was the flying pilot and initiated a gradual descent. We leveled off at FL200 initially. We remained at that altitude until further stepped down by Approach Control. The First Officer continued to fly the aircraft and manage fuel transfer while I consulted One Engine Inop App and Landing and One Engine Inop Go-Around Checklists; checked landing performance; notified the FA; made an announcement to passengers; and notified Dispatch via ARINC. (Our ACARS was deferred.)By the time all of the above was completed; we were in the arrival environment of ZZZ and descending below 10;000 feet on radar vectors for a downwind to [Runway] XXL; the longest available runway. I chose to perform the landing and we transferred controls. The weather was VMC with clear visibility and light winds out of the east directly down the runway. We landed without incident and exited [Runway] XXL. We were met by emergency vehicles who asked us our condition and whether we needed further assistance. We required no additional assistance. We were cleared to taxi to [the gate] under our own power. We arrived at the gate on time. The whole scenario was textbook smooth. The First Officer did an excellent job flying the aircraft; managing fuel; backing me up with checklists; handling radio frequencies; and both Pilot Flying as well as Pilot Monitoring duties. In my address to the passengers; I downplayed the incident; telling them that we had an issue with oil pressure on one of our engines and had declared a precautionary landing with ATC. Consequently; they would likely see emergency vehicles on the side of the runway as a precaution and to please not be alarmed. When we arrived at the gate; I again addressed the passengers from the Flight Attendants station at the main cabin door by PA. All appeared to be content and in good spirits as they departed the aircraft.


Synopsis: An ERJ flight crew reported that during cruise an engine's oil pressure dropped into the red range.