Date: 202112
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: Citation V/Ultra/Encore (C560)
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Turbine Engine
Component problem: Failed
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Troubleshooting
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed in Emergency Condition; General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Approximately one hour into flight both Master Warning and Master Caution illuminated. Quick scan revealed Engine #2 (pilot right side) had shutdown. SIC was Pilot Flying. I immediately notified ATC of engine failure and requested drift down altitude of FL350. After consulting ECL I requested FL330 for possible engine restart. Instruments indicated rotation on both N1 and N2. Based on this I attempted and successfully completed the in-air engine restart in accordance with the checklist. Upon applying power ENG2 OIL Pressure tape exceeded the upper red limit. Tried unsuccessfully several times to regain thrust; however; I was unable without fear of catastrophic damage to ENG2. At this time I elected to keep ENG2 at idle for EMER power if needed. I then took the controls and radios; instructed SIC to consult single approach and landing checklists. I [requested priority handling] and diverted to ZZZ. I disengaged autopilot; and requested immediate decent. Had SIC start APU to provide additional power and bleed air supply. Upon landing I shut down ENG2 and continued to FBO single engine without further incident.


Second narrative: I was pilot flying for this flight. At cruise FL410 I was scanning the instruments and noticed [that] a master warning and caution lights were illuminated and immediately notified [the] Captain that we were having engine issues on the right side. He confirmed this and pulled out [the] emergency checklist. I managed the flying while [the] Captain was running the checklist. We determine we have N2 and N1 rotation and we successfully attempt a restart per emergency checklist. Right engine restarts without any notable issues. When increasing throttle from idle position; engine oil temperature exceeded normal temperature range and throttle was brought back to idle. This condition was tested a few times with the same result. Crew decided to maintain the engine in flight idle in the event that we need to have emergency power using the affected engine. FO (First Officer) transfers controls to Captain for approach and landing. Emergency checklist of one engine approach and land was performed without incident. Airport Fire Rescue followed after touchdown and taxi to FBO without incident. Aircraft was shut down and inspected for any physical evidence to the engine. All outward structures were unremarkable. There was some residual oil on the bottom of the metal cowling at the engine outlet.


Synopsis: C500 flight crew reported an engine roll-back at cruise. The flight crew restarted the engine; left it at idle due to oil pressure indicating high and performed an air turnback to landing.