Date: 201711
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Dusk
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Hydraulic Fluid
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Workload; Troubleshooting; Time Pressure
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We were enroute when we experienced a C HYD QNT EICAS message. We monitored the Hydraulic quantity and observed it decreasing at a rapid rate and were concerned that we would eventually lose the center system evolving into a C HYD SYS PRESS situation. The procedure would require us to extend both the flaps and landing gear using alternative means. We were concerned about making a heavy weight landing into a high elevation airport with compromised flight controls and partial flaps that would require a higher approach speed. Additionally; the possibility of hot brakes and the complexity of a go around and not being able to retract the landing gear was discussed. The wind would require us to make a circling approach; due to the proximity of high terrain in the area. The hydraulic quantity continued to decrease. Flight Control was contacted and our situation and concerns were discussed. Maintenance was included in the loop. Eventually; a [technician] was contacted and brought into the conversation. We talked about the need for additional time to configure the aircraft; the possibility that we might not be able to clear the runway after landing; and of course; hot brakes. The decision was made to change our destination. The increased fuel burn would reduce our landing weight and; our opinion would give us better runway options. By this time the hydraulic quantity had decreased to a point requiring alternate extension of the flaps and landing gear. Flight Control contacted ATC and advised them of our situation. She explained the need for extra time to configure the aircraft and the possibility that we would need to be towed from the runway. The EICAS message C HYD SYS PRESS displayed and we started our descent. We asked to be vectored off of the profile descent to allow us extra time to configure the aircraft due to using alternative flap and landing gear extension. We advised ATC that we may or may not be able to exit the runway on our own because of the possibility of losing the nose wheel steering and the possibility of hot brakes. We were advised that equipment was standing by. The AOM C HYD SYS PRESS procedure was completed. The landing checklist was completed and the emergency egress was reviewed. The approach and landing was normal for our configuration. Manual speed brakes were extended and the reversers operated normally. Moderate manual braking was applied and we easily stopped the aircraft so that we could have exited on the taxiway. The initial brake temperatures were indicating 0-1's. There was sufficient nose wheel control that we felt that we turn off of the runway and have the brakes inspected on the taxiway. We were both surprised to see the CFR (Crash Fire Rescue) vehicles rapidly approaching the aircraft. We were advised by [Airport]Fire Control that we had a small fire in the left MLG (Main Landing Gear). The engines were shut down and the fire was extinguished. Fans were placed around the MLG and the temperatures were monitored. The highest cockpit temperature indication was a 5. Eventually; the aircraft was towed from the runway back to the ramp. We were met and debriefed by maintenance. Later they determined that the leak was caused by a failed high pressure O ring in the left wheel well.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A Boeing 767 flight crew reported the loss of a primary hydraulic system. A diversion to the most suitable airport was successfully accomplished.