B767 flight crew reported loss of C hydraulic system during cruise. The flight crew continued to destination airport and made a precautionary landing.
Synopsis
B767 flight crew reported loss of C hydraulic system during cruise. The flight crew continued to destination airport and made a precautionary landing.
Narrative
I was on break when the event occurred; but arrived after break and was briefed on the center system hydraulic leak and QRH actions taken. We reviewed the situation and QRH actions for loss of C HYD pressure in case the remaining fluid leaked when the C HYD system was pressurized. On approach we [requested priority handling]; ran remaining items on the C HYD quantity checklist and configured early for the ILS XXL. At 1500 ft. AGL on a coupled ILS approach we got a TCAS TA followed by a climb RA. Despite being a priority and having no visual on any aircraft; we respected the RA. We were visual with the terrain but inflight visibility was hazy. The RA was abnormal because during the RA the target stayed at 00 and at the tip of the airplane display during the 1000 ft. climb in response to RA. Tower announced there was no traffic in the area; but we elected to follow the RA. After resolution; we were too high to resume the ILS; and asked for a 360; but accepted vectors back to ZZZZZ to re complete the full approach. We had briefed no configuration changes during missed approach due to our hydraulic situation. We reset the Mode Control Panel (MCP) and FMC after RA completion and continued for subsequent approach. We got clearance for direct ZZZZZ and then clearance for the approach. Slight deviations to altitude occurred as we tried to re engage VNAV path. We realized the issue was re cruising VNAV and then VNAV path properly engaged just prior to ZZZZZ. Again; during the descent through 4500 MSL onto the dogleg out of ZZZZZ we again got a TCAS TA followed by a climb RA. This time we noted the altitude of the target always reading 00 and staying with us. Tower assured us that we did not have traffic in the area. We applied the direction on page x that complying a second time with a likely anomalous RA would subject the aircraft to further hazard. On ILS final the nuisance RA was not an issue; and we landed uneventfully. We cleared the runway when the hydraulic system showed normal indications. Once clear; we had fire crews examine the aircraft for leaking fluid. We asked for and received tug assistance to a hard stand and deplaned. Local Maintenance personnel met the aircraft; and confirmed that the C HYD RES was empty.
Second reporter narrative
I was the Pilot flying (PF) and First Officer (FO) was PM. FO was still on break. During the last 2 hours of cruise; all auto-flight on at FL350; EICAS warned us of low center hydraulic system quantity. We noted C HYD QTY at 0.48 with refill light on and followed checklist guidance to turn off all center pumps until final approach. After the checklists were complete; we elected to let FO remain on rest; but wake them 15 minutes early to review the checklist completion issues together. We called Dispatch; and spoke with Maintenance. They agreed with the continuation to ZZZ; with the likelihood that normal configuration for landing was still likely; and Dispatch agreed to notify the station of a need for tow in and the airport of our need for the long Runway XXL which is normally takeoffs only. FM (Flight Manager) was called to the cockpit; and briefed on the issues. We told them to share the problem with the crew; that a prep for evacuation was not needed yet; and that the passengers would not be briefed unless the situation deteriorated. They asked what could make this worse and I shared the issue of a 20 flaps non normal landing was possible if the rest of the fluid leaked out before final approach. In that case we would reevaluate the need to prepare for evacuation. They understood everything and went back to the cabin. After FO came back to the cockpit; and during descent; we [requested priority handling] as we were not sure if we would be stuck with only 20 flaps (alternate extension method) if the hydraulic quantity ran out. On downwind; we completed the deferred checklist items and were able to fully configure the aircraft with gear and 30 flaps. C HYD quantity decreased to about 35% after gear and flaps extension. We cleared the ILS to the longer Runway (XXL) which for ZZZ is not the standard for arrivals. We had coordinated with Approach Control about 30 minutes prior so they could switch the ILS to the inner runway. Weather was about 1 mile visibility mostly due to smog; but cloudiness still allowed us to see most of the terrain north of the airport while above 4000 ft. At 1500 ft. AGL on a coupled ILS approach we got a TCAS TA followed by a climb RA. Despite being a priority aircraft and have no visual on any aircraft; we respected the RA. After resolution; we were too high to resume the ILS; and asked for a 360; but accepted longer vectors back around. Due to the checklist directions for a C HYD malfunction; this maneuver was flown fully configured. Since we could not use a standard go-around procedure; and the maneuver required me to hand fly; minor deviations from 6000 MSL assigned altitude occurred until we reset the flight director. We still had plenty of fuel for about 2 hours. We were vectored by to the ZZZZZ IAF for the ILS XXL with gear down and 30 flaps. We got clearance direct ZZZZZ and then clearance for the approach. Slight deviations to altitude occurred as we tried to re engage VNAV path. We realized the issue was re cruising VNAV and then VNAV path properly engaged just prior to ZZZZZ. Again; during the descent through 4500 MSL locked onto the dogleg out of ZZZZZ we again got a TCAS TA followed by a climb RA. This time we noted the altitude of the target always reading 00 and staying with us. Tower assured us that we did not have traffic in the area. We applied the direction on page x that complying a second time with a likely anomalous RA would subject the aircraft to further hazard. On ILS final the nuisance RA was not an issue; and we landed uneventfully. We cleared the runway noting proper C HYD pressure at all times; and the preserved fluid for brakes and steering. Once clear; we had fire crews examine the aircraft for leaking fluid. There was none evident. We asked for and received tug assistance to a hard stand and deplaned. Local Maintenance personnel met the aircraft; and confirmed that the C HYD RES was empty.Superior job by my flight crew; and the Flight Attendants who were very attentive to my directions. Both FO's were fantastic at ensuring the safest operation of the aircraft; and supporting me as the PF; despite the dramatic challenges we faced. They ensured we all maintained the proper awareness in a very challenging priority approach; including language barriers; poor visibility; terrain; and challenges to using auto flight as the auto pilot needed to be off at certain points during a low altitude condition. Checklist direction on fluid amounts below 50% could be much clearer; and I will submit suggested changes. The manual seems to indicate that if the C HYD system goes into isolation for reserve brakes and steering (occurs below 50% QTY) that the normal movement of flaps and gear may not occur. We knew the center system was in isolation (light on the right side panel illuminated during descent and prior to turning the CTR pumps on again). We stuck with the checklist discipline of just doing the deferred items on the QTY checklist but had the uncomfortable feeling that we might end up with a gear sequence error if the handle was lowered and zero fluid was available due to the isolation condition. We had tons of time to review such guidance and clarity had it been in the manual. It should help the crew with confidence to run the QTY checklist until the system cannot maintain pressure; then switch to the pressure checklist to complete configuration to flaps 20.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.