B777 flight crew reported engine oil pressure loss during cruise resulted in inflight engine shutdown and divert.
Synopsis
B777 flight crew reported engine oil pressure loss during cruise resulted in inflight engine shutdown and divert.
Narrative
This is a story of what went well; what could have gone better; and some suggestions for process and training improvements. I spent a lot of time writing this in the interest of improving safety and increasing awareness of some issues; and I hope the company takes the time to read it thoroughly and methodically. I know the company processes a lot of reports; and in my experience sometimes reports are misread and/or misunderstood due to haste. Please don't rush through this one. I provide the following background to lend credence to my observations and suggestions:-- I've logged approximately XX;XXX hours of total flight time in XX years. I've flown at air carrier X for almost XY years. I've been a first officer and captain on every jet in our current inventory (some more than once) as well as a first officer on the 747. I have also served as a line check pilot on three other fleets.-- The first officer on this flight has been at air carrier X for a little over a XZ years and has prior heavy jet experience at another airline. We flew together once previously; earlier this year.-- The two relief pilots were both hired at air carrier X only a XA years ago. They were asleep on break when the event occurred. This was the first flight of the trip. The first officer was the PF for this leg; and I was the PM. About an hour after takeoff in cruise at FL320 I noticed the right engine oil pressure fluctuating rapidly between 180 and 250 psi; with all other engine parameters normal. This seemed to both of us like an indication problem. However; I also noticed on the maintenance parameter pages that both channels of the EEC (Electronic Engine Control) were showing similar fluctuations (pilots aren't trained to use these pages but should be). This is not addressed in the flight manual or systems training; but my assumption was that the two EEC channels each have their own pressure sensor; implying the possibility of a real problem and not just an indication problem. We sent an ACARS message to Maintenance Control asking for their thoughts. After a 15+ minute delay (which seems excessive to me); they replied that the fluctuations were within normal range and we should follow our QRH procedures. The 777 doesn't have a QRH; and there are no procedures for fluctuating indications within normal range; so we decided to monitor and continue. It wasn't normal; but it wasn't necessarily bad. We had been observing this for almost an hour at this point. I entered a discrepancy in the maintenance log. A few minutes later the right engine oil pressure dropped below the minimum and we got the ENG OIL PRESS R EICAS message and checklist. All other engine parameters were still normal. We both agreed to take a moment to 'wind the watch' and not rush into shutting down a good engine for a potential indication problem. We also both agreed that we would likely be diverting; even if it was only an indication problem; because continuing across the ocean for another XX hours didn't seem like a prudent course of action. Our nearest suitable airport and ETOPS alternate was ZZZ.In preparation for a diversion and possible descent; I directed the first officer to initiate a 5NM route offset (triggering an ADS-C report to ATC due to a route deviation) while I initiated a SATCOM call with Dispatch and Maintenance Control. As soon as I started explaining the situation; at XC:57 the right engine surged with a loud bang. I told Dispatch and Maintenance Control that we were shutting down the engine; diverting to ZZZ; and to stand by. We initially actioned the 'Eng Lim / Surge / Stall' QRC checklist. After the completing the QRC (it only has two steps); I decided to abandon this checklist and action the ENG OIL PRESS R checklist because 1) it was an annunciated checklist that was sitting there waiting for us; and 2) we knew that with low oil pressure we would be shutting down the engine anyway. In retrospect; I should have gone straight to the annunciated checklist and notbothered with the 'Eng Lim / Surge / Stall' QRC. After securing the engine; I paused the ENG OIL PRESS R checklist and actioned the 'Driftdown' QRC checklist in its entirety. Because we had already established an offset; we were ready to descend immediately. I directed the first officer to expedite down below FL290 so we could turn around. We then went direct ZZZ using the FMC ALTN (Alternate Airport) page; which changes the destination and deletes the old route. Once pointed in the correct direction; we increased speed to the ETOPS divert speed (CO SPD (Speed) in FMC) of 330 kts. At this faster speed the max altitude was approximately 15000 feet; so we selected 14500 in the FMC CRZ (Cruise) page and MCP (Mode Control Panel) and continued descending. There was no need to descend all the way to 10000. At this point I completed the remaining steps in the ENG OIL PRESS R checklist. Aviate; navigate; communicate - in that order. Next; I sent a CPDLC report to ZZZ [ARTCC]; and the only details I included were direct ZZZ; and descending to 14500. There would be plenty of time to provide additional information. They responded with a clearance to maintain block altitude FL120 to FL280. The SATCOM call with Dispatch and Maintenance Control was still open; so I returned to that; provided them with an update; and ended the call. During the event thus far; we had received a couple of calls from the cabin that I was unable to answer due to higher-priority tasks. I called the forward galley flight attendant; gave them a briefing; and asked them to wake the purser and other F/As who had just started their break. We agreed that I would not make any PA announcements yet because most passengers were sleeping and we still had approximately 2:30 of flight time remaining. A few minutes later; we got a CPDLC message from ZZZ [ARTCC] asking if we were going to ZZZ This was strange; because they should have known this from the emergency report. We replied yes; and they cleared us direct to ZZZZZ. This intersection is close enough to the direct route that I accepted it. A few minutes later they re-cleared us direct to ZZZ (the VOR; not the airport); and I accepted that as well. I don't know what this was all about - maybe a process breakdown on their end? A distraction occurred with the direct routing we first initiated and each direct clearance we received from ZZZ [ARTCC]. Going direct to some point with no runway loaded in the FMC resulted in a landing fuel of 0.0 and the 'Insufficient Fuel' EICAS message. Each time; loading a runway and approach resolved the issue and restored normal fuel prediction numbers. I don't know why this happened and maybe I'm missing something; but someone should investigate it as a potential anomaly. ZZZ [ARTCC] also asked us our ETA for ZZZ; and this posed an interesting question. With a XXX mile direct route and no winds in the FMC; our ETA prediction could be wrong. I tried loading some along-track LAT/LONG waypoints and requesting winds for 15000 feet; but the wind uplink failed due to no data available. We were showing an ETA of approximately XG:30. Dispatch said they were showing approximately XG:50; but the new flight plan had us too slow; 17000 feet (higher than our max altitude at current weight and 330 KIAS); on a non-direct route; and landing on the wrong runway. This new flight plan was not very helpful. I knew we had plenty of fuel; so I did not follow up on this with Dispatch. Someone should investigate potential programming errors or limitations of our flight planning software with respect to single-engine ETOPS diversions. We had every intention of dumping fuel; but no intention of dumping fuel early; so we needed to know how long it would take to dump prior to landing in order to prevent an unnecessary delay. To determine this we actioned the 'Fuel Jettison' checklist first step; as arming the system shows time remaining to dump. After obtaining this information (25 minutes); we disarmed the system. Webuilt a point 30NM from ZZZ at 10000 feet to provide a top of descent point from 14500. We decided to start dumping fuel 35 minutes before TOD (Top of Descent) to be complete 10 minutes before TOD. This would leave us with around 50000 lbs of fuel and put us just below max landing weight. Earlier in the event; immediately after securing the engine; I woke both Relief Pilots in case we needed their help. In retrospect; when I woke them I didn't actually have time to talk. If I had to do this over; I would wait until the high-priority tasks were complete and then call them on the interphone to explain why they were being woken up. By the time the Relief Pilots returned to the cockpit; everything was stabilized and we were just passing time on the long divert: debriefing what had already occurred; considering options; trying to think of anything we missed. I briefed the Relief Pilots on everything; answered questions; and then went to cabin to brief the purser and some of the other F/As in person. I reiterated the briefing items and said (multiple times to multiple F/As) that we expected a normal landing with no evacuation preparation. I did not want any confusion on this point. Because most passengers were still sleeping; we decided not to make any PA announcements until 1:15 prior to landing. At that time; I would inform the passengers of the diversion due to a 'mechanical malfunction' and give them a little time to wake up and use the lavatories; but not so much time that people might start to get anxious or nervous. We were fortunate in that there was no turbulence or weather anywhere on the entire diversion. Somewhere during divert I also entered another maintenance log item for the engine failure. This was the first officer's leg; and they were doing a great job flying. I asked how they felt about landing; and they were confident. In fact; they had just done engine inoperative landings in the simulator two weeks prior. The weather was good; and I saw no reason to take away their landing. They briefed it thoroughly. I added reminders about not selecting F20 (Flaps 20) or lowering the gear until near glideslope intercept; and about the tendency to float on a F20 landing. I said I'd ask for a 15-mile final to give us plenty of time to do it correctly the first time. The plan was to use AB4 (Auto Brakes 4); come to a stop on the runway for inspection by CFR (Crash Fire Rescue); and then taxi to the gate. At the pre-planned time we initiated the fuel jettison. We ended up dumping 93900 lbs of fuel with 54600 remaining. Unfortunately; the wings did not jettison at the same rate. The left wing tank jettisoned faster than the right; even after accounting for fuel the left engine was using. This led to a 5000 lb imbalance at the end of the jettison procedure. The limitation for landing is 4000; so we initiated fuel crossfeed and planned to land in that configuration. I would not delay landing to meet the limitation; but I figured we could probably meet it in the time remaining. Actual imbalance at landing was just under 3000. The lesson here is that; if possible; give yourself time after jettison to correct any imbalances. Approximately 45 minutes prior to landing; we got a call from ATC. I replied that we had turned around and were almost back to ZZZ; and wouldn't be needing those frequencies. They were quite surprised; as they had not been notified. We had no reason to notify them with an active CPDLC connection; but I'm not sure if someone else (ATC or Dispatch) was supposed to. This should be investigated. The approach and landing went as planned and briefed. One interesting point was that from a vector 90 degrees to the final approach course; ZZZ [TRACON] said something like; 'Turn left to a heading of your choice to intercept the localizer.' I think they were just trying to be accommodating; which I appreciate; but this is not a real clearance. I didn't press the issue; though; and we just did what we
Second reporter narrative
Approximately an hour into our flight; CA and I each noticed the rapidly fluctuating right oil pressure on the compressed engine indications and started discussing. We pulled up the maintenance page and saw that both channels of the EEC (Electronic Engine Control) were showing rapid fluctuations; with different numbers. In general; the fluctuations were between 200-229; but the low and high that we saw was 180 and 250. We discussed and monitored and sent messages to Dispatch/Maintenance Control for about an hour prior to receiving the EICAS message. During that time I closely monitored our alternates; weather; and position with respect to the CP (Critical Point); as well as proximity to other aircraft. I pulled up and reviewed the Diversion Planning Guide in the QRG (Quick Reference Guide). Captain and I both thought that it was probably a sensor/indication issue; however; the captain sent a message to Maintenance Control with details. It seemed like a long time before we heard back from Maintenance Control (maybe 10-15 minutes?) and the response indicated that they were not particularly interested or excited in/with our fluctuating oil press indications. The response was I don't see any faults in AHM (Aircraft Health Management) and I don't see any previous history. The oil pressure limits are between 70 PSI-360 PSI. Please follow your QRH". (Small point - we do not have a QRH on the 777.) We began to discuss how far we were comfortable taking the aircraft and possible diversion; not knowing if it truly was a sensor issue or a real issue; and with limited diversion airports on the way to ZZZZ.CA wrote up the fluctuating oil pressure. Shortly thereafter; we received the ENG OIL PRESS R; EICAS message and the oil pressure decreased rapidly to about 20; oil quantity increased to 29. The non-normal checklist came up and we looked at it; but before rushing to shut down the engine CA suggested we take a second to evaluate. In an emergent situation unless absolutely necessary (e.g. RTO (Rejected Takeoff)); I prefer to slow things down; move with deliberate speed as rushing causes errors. The captain was on the same page. We took a second to evaluate and discuss before shutting down the engine. Neither of us wished to shut down a good engine. We then heard and felt a loud bang! (compressor stall sound) from the R engine. I continued to fly the airplane and CA ran checklists. We went to the engine limit/surge/stall; immediate action item on the QRC; but after reducing the thrust lever went back to the ENG OIL PRESS R non-normal checklist. Both checklists would direct us to shut down the engine.Our divert airport was ZZZ; behind us. CA did an excellent job of managing and keeping me in the loop with the checklists; while soliciting/accepting input. I executed an immediate R5 (Right 5) offset; and when appropriate; I interrupted to ask him for the drift down checklist so that I could start down before airspeed decayed. CA sent the divert report and once we descended below F290; I made the 180° turn towards ZZZ per our clearance. We used 14;500' as our drift down altitude and 329 kts per the FMS optimal recommended altitude and speed. We had clear weather and mostly smooth air so we were able to maintain 329 or close to it for most of the air return. Flight Attendants had been calling us and after about the third or fourth ding CA was able to pick up and tell them he would get back to them. We secured the engine; ran the checklists; notified FAs; ATC; Dispatch/Maintenance Control via Satphone; briefed FAs; woke the Relief Pilots; and continued our slow drift down. FAs were briefed with emphasis to expect normal landing with no evacuation. By the time the Relief Pilots came back up everything was done except the fuel jettison. CA and I discussed and checked the time to dump which was 25 minutes. I suggested we start 60 to 75 minutes prior to landing so that everything would be done by the time we got busy again; we agreed no reason to dump fuel too early. Relief Pilots came up; we were drifting down w all checklists and notifications complete; with approx 2 hours to fly to ZZZ. CA briefed them and used the time as a "teaching moment" to share additional info and considerations - Relief Pilots were both fairly new to the aircraft and air carrier X and had good questions and input. CA has a lot of knowledge to share; good use of time. We discussed the landing; CA asked how I felt - very awake and alert and well prepared for single engine landing - so he said we would continue our roles as pilot flying and pilot monitoring. At the appointed time; we began fuel jettison and completed it within expected time. FAs told us pax were all asleep; we agreed to wait to make announcement until closer but still give them time to use lav; notify people of return; etc. CA made a PA approximately 75 minutes prior to landing and said returning to ZZZ due to mechanical issue. All briefs were thorough and encouraged input from all four pilots. Normal landing (we discussed deck angle and speed differences) with F20 (Flaps 20); AB4 (Auto Brakes 4); came to a stop on the runway so CFR trucks could inspect; then taxied to the gate uneventfully. Once at the gate; a barrage of people came into the flight deck asking for info and debriefs. This included someone from airport operations (I think that's what he said); Maintenance; Customer Service; also Chief Pilot; Dispatch/Maintenance Control by phone; etc. After passengers deplaned we debriefed with FAs. At approximately XH:30 I turned on my phone and my pairing had been modified. Apparently scheduling reassigned me to be on a XJ:00 DH (Dead Head) to ZZZ1; for a later flight to ZZZ2. It took a minute to realize that they wanted me on a flight in 90 minutes after flying all night; handling the air return to ZZZ. I spoke with Chief Pilot; he said he would take care of scheduling and not to worry about the reassignment. I left to get some rest. Takeaways:I think that the situation was well handled and went well as a result of :--good training--discipline and adherence to SOPs--good leadership and taking a breath to evaluate situation before rushing to flip switches--good CRM and soliciting/accepting input--great job by cabin crew with paxThere were some (mostly small) things that were unexpected or could have gone better:-- response from initial ACARS message to Maintenance Control - response time seemed unnecessarily long; and the response was not helpful --prioritizing the Eng limit/surge/stall checklist vs the non normal ENG OIL PRESS R checklist was a little messy although I think it worked out fine; as always; there were a lot of checklists to prioritize--prioritizing waking up Relief Pilots in the middle of running checklists; CA said he was going to wake them; and I thought; maybe wait on that a bit; but it wasn't a big enough deal in my mind to discuss when we had other more pressing things going on; and CA had a big workload already; didn't need distraction of more input/options. We discussed later in debrief.--ATC - every sector asked the same questions; do they actually communicate w each other?-- Altimeter setting/transition level over international waters - clearance was maintain FL120-FL280. We set ZZZ local altimeter going through 18; no terrain just ocean; and one less distraction but we looked it up after getting home. We should include it in the manual.--fuel jettison - resulted in an imbalance; not a big deal but we landed while balancing fuel. I had not expected that and next time I'll advocate starting a little earlier so we are not balancing when things get busy (CA assigned one Relief Pilot to watch balancing). Might be something to consider including in training when we run fuel jettison checklist in the training environment. Worth a note. --"Airport Operations"?!! Who was that guy and why was he on the aircraft at all; and pushing into the flightdeck as soon as we landed? The CA showed him his badge; said we had a mechanical and returned and referred him to air carrier X for other details. I think I would have said First Officer; air carrier X; please contact air carrier X for all other details. It was strange and uncomfortable to have that guy pushing in like that. -- The BIGGEST issue I had with the whole event was scheduling. I am grateful for the Chief Pilot taking care of it; but I think it is absurd for the scheduling to reassign us after an event like that to be on a XJ:00 flight to ZZZ1. I had been up all night; flying and dealing with non normal situation; and to then be pressured/expected to run to a flight to ZZZ1…. I believe that this is a really bad practice; and needs to be addressed immediately. I think of the younger; less experienced pilots - especially those on probation - who might be tempted to comply despite levels of tiredness and/or mental/physiological responses to stress; situations like shutting down an engine and flying 150 minutes; in the middle of the night; and it could create an undesirable situation particularly on the subsequent flight. Please consider making appropriate changes so that scheduling has reasonable procedures to follow in this situation."
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.