B737 MAX 9 flight crew reported engine indication malfunction inflight. Flight crew continue to destination and landed safely.
Synopsis
B737 MAX 9 flight crew reported engine indication malfunction inflight. Flight crew continue to destination and landed safely.
Narrative
Day 3 of 3; leg 1 of 2. Normal show timeline to aircraft. Normal preflight procedure(s) and briefings were accomplished. Pushed from Gate XX for de-ice pad X. Weather conditions were conducive for a single engine taxi. No active freezing precipitation existed. We elected to request only Type 1 deice. We deiced in pad Y with only the right engine running; APU off. Deice supplementary procedure was adhered to. Post deice accomplished engine runup per Flight Manual. Remainder of ground OPS was normal and in accordance with the Flight Manual. Planned flaps 5/ reduced thrust/ ENG AI ON takeoff for RWY XX L. We did confirm a 5 minute engine warm up and confirmed OIL TEMP was above 31C. We also did the MAX ENG Runup in conjunction with the takeoff (50% N1 for 5 SEC). The takeoff and initial climb out was normal. We climbed with the ENG AI ON through multiple layers of icing conditions. As we broke out on top passing 10;000; we got a system annunciator light for 'ANTI-ICE' and 'ENG' and the associated master caution lights. Upon investigation; the overhead 'ENG ANTI-ICE' light was illuminated; as well as the 'REVERSER LIMITED' light. We later referenced MAX 9 performance data decrement for INOP TR which was not a factor based on aircraft weight and runway condition report/field conditions. At this time; I noticed the left duct pressure was indicating 80 PSI (right duct pressure was at 35-40 PSI). FO(PF) took the radios and aircraft. We elected to stop the climb at FL230 until ensuring there was no indications of impending pressurization problems. No tripped Circuit Breakers (CB) were noted at this time. Both engine parameters were matched and nominal. I referenced (MAX) Engine Anti-Ice Non-Normal Checklist (NNC). Neither BLEED light was illuminated and the checklist was ended with 'avoid icing conditions'. The (MAX) REVERSER LIMITED NNC was referenced. The checklist was concluded with an info note of 'thrust reverser does not deploy or reverse thrust is limited to idle upon landing' end of checklist. There was no high duct pressure NNC (annunciated or annunciated) to reference.I elected to conference with Maintenance Control via phone patch with dispatch. Maintenance control could not associate the various failures/indications on the flight deck; but did admit that the aggregate issues were anomalous. Due to the icing condition restriction and no further system complications or indication of worsening aircraft performance; we elected to continue to ZZZ1 with dispatcher's concurrence. We climbed to planned cruise altitude and continued to monitor engine health/ duct pressure in cruise. We did not have any issues pressurizing or controlling cabin temperature. We entered MX issues into Electronic Logbooks (ELB). Remainder of cruise segment as normal. Left duct pressure would continue to read 30-40 PSI higher than the right during all remaining flight phases.After the approach briefing and the descent checklist was complete. We received a descend via clearance by voice. As we began to descend out of ~34000ft MSL I noticed ENG 1 oil pressure drop rapidly from ~90% to 17% and it stabilized initially at 17%. The oil quantity indication swapped to inverse video with the LO placarded adjacent to the readout. All other engine indications were normal including OIL TEMP/ PRESSURE / VIB etc. I informed ATC of an issue regarding our engine health. I inputted an ELB and informed dispatch of the issue. When the OIL QTY continued to decrease; we [requested priority handling] with ATC and informed dispatch. I gave the FAs a briefing. No special instructions or bracing was required at the time of the briefing. We requested Airport Rescue and Firefighting (ARFF) with ATC as a precaution. We were given priority arrival to [Runway] XY R. Throughout the descend we continued to monitor the OIL QTY and it steadily reduced from 17% to 9% over the course of 15 minutes. I started the APU passing ~FL180 as a precaution. The FO(PF) continued to fly the aircraft. There is not a LO OIL QTY NNC to reference. Preemptively; I referenced Engine LOW OIL PRESSURE which pointed to (MAX) Engine Failure or Shutdown NNC. The left engine continued to operate normally with nominal OIL pressure throughout the approach. We were prepared for an ENG shutdown should OIL pressure or other engine indications dictated it. Outside the FAF we were notionally planning a go-around (assuming no fire indications developed). Inside the FAF we planned to increase speed to accommodate for a flaps 15 landing; we elected to use auto-brakes 3 and I referenced non-normal landing distance for One Engine Inoperative Landing (Flaps 15). XY R easily accommodated that condition. FO(PF) performed a stable approach. WX conditions were favorable; and we were visual with the airfield well prior to the localizer intercept. After landing; normal transfer of controls occurred at 80 knots. I taxied the aircraft clear of RWY XY R at high-speed taxiway 1. Shortly after clearing the runway; we shut down the #1 ENG and cleaned the aircraft up. After landing the BLEED and MAINTANENCE overhead lights illuminated. We contacted ARFF on a discrete frequency. The tower controller and ground controller were monitoring this frequency. We had ARFF visually inspect the #1 ENG for signs of leaking / damage. None were found. We would continue to taxi under our own power to gate XY via TWY 2; 3. At the gate XY; Maintenance Control boarded the aircraft and reported that the engine oil quantity was fully serviced. They also discovered 5 CBs tripped. At the time of the report; myself (PM) and the FO(PF) suspect that they all tripped on the ground after landing/ENG shutdown and were associated with the BLEED & MAINTANENCE overhead light illumination. Of note: I had checked the CBs multiple times when airborne and did not note and tripped CBs at that time. We debriefed with the Chief Pilot; and I verbally reviewed the issue with the dispatcher. Maintenance Control continued to trouble shoot various spurious errors. The aircraft was subsequently removed from line operations. Myself and the FO debriefed and we were authorized to continue our pairing as amended.
Second reporter narrative
We had a normal show to the aircraft in ZZZ and conducted normal preflight checks. Due to the conditions we elected to de-ice with type 1. After de-icing and configuring the aircraft; we taxied for departure. Prior to departure we conducted a run up to 50% N1 for 5 seconds before initiating the takeoff roll. We climbed through a few layers with no icing noted; but kept the ENG ANTI ICE on until exiting icing conditions. At approx 10;000' the MASTER CAUTION illuminated with an ENG and ANTI-ICE recall. Lights illuminated were left REVERSER LIMITED and left ENG ANTI-ICE. We also noted that the L ENG duct pressure was very high (approximately 70-80psi). I engaged the autopilot in order to reduce my workload and follow along with the checklists. We each took a moment in order to conduct a thorough scan of the instruments; systems indications; and Circuit Breakers (CB). The CA (PM) announced that he was going to run the appropriate non normal checklists. We asked ATC to maintain FL230 while we troubleshot the issues and ensured there were no pressurization issues. The (MAX) Engine Anti Ice checklist was accomplished advising us to avoid icing conditions. The (MAX) Reverser Limited checklist was referenced and we noted that the reversers may not deploy or may deploy to idle only after touchdown. The CA requested and received a phone patch to Dispatch and Maintenance Control. Maintenance Control noted the anomalous indications but could not determine a root cause. Maintenance Control left it up to us and our dispatcher to determine whether or not to air return. As the ENG ANTI-ICE checklist advised us to avoid known icing; we elected to continue on to ZZZ1 instead of an air return to ZZZ. We monitored all systems closely throughout the flight. After the Arrival Brief and subsequent Descent Check; the CA noted that our L Oil Quantity had rapidly decreased from normal range to 17% and was slowly dropping. ENG OIL PRESS and ENG OIL TEMP was normal. The CA advised ATC that we may be soon [requesting priority handling] due to adverse engine indications. As there is no ENGINE LOW OIL non normal checklist; we proactively looked up the ENGINE LOW OIL PRESSURE checklist in the event that we ran out of oil. The checklist referred us to the ENGINE FAILURE or SHUTDOWN checklist. Oil quantity was still slowly decreasing so we elected to [request priority handling]. We planned to attempt a normal landing unless the engine oil parameters dictated an in-flight shutdown; in which case we would execute a go around if outside of the FAF. If the engine failed inside of the final approach fix we planned to accomplish a SE flaps 15 landing and the CA referenced the non normal landing distance. Engine oil dropped as low a 9% during the approach but other parameters remained within limits. An uneventful landing occurred to XX R in ZZZ1. During the roll out another MASTER CAUTION occurred with associated MAINT and (L) BLEED lights. After exiting the runway; we shut down the #1 Engine. We were met by Airport Rescue and Firefighting who ensured that we were not leaking any flammable liquids. We taxied to gate XY where Maintenance Control personnel met the aircraft. They noted multiple popped CBs that the CA and I presume popped after landing; as we had checked the CBs in flight. We were contacted by the Chief Pilot and after a brief conversation were cleared to continue our pairing. The aircraft was removed from service by Maintenance Control after they were able to duplicate issues.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.