B737 MAX 8 flight crew reported smoke in the cabin during departure climb. Flight crew returned to departure airport
Synopsis
B737 MAX 8 flight crew reported smoke in the cabin during departure climb. Flight crew returned to departure airport
Narrative
I accepted the aircraft after reviewing the logbook noting that there had been multiple bird strikes on landing the previous morning. It appeared that engine 1 had ingested bird(s) as well as the Captain's Pitot tube. In my Threat and Error mitigation take off briefing; I noted this and said to prepare for the potential of stagnant/erratic airspeed on departure and potential engine problems. I also briefed the known 737 MAX issue pertaining to the LRD (Load Reduction Device) and the potential for smoke in the flight deck should this activate. We briefed that we would mitigate this threat by conducting the QRC checklist at 400 feet rather than the standard flaps up clean altitude if an engine fire or severe engine damage event presented itself. We also briefed that we would don quick donning masks if necessary; should the LRD known issue occur.We pushed back about three and a half hours late from schedule and taxied out on one engine. We prepared a second ACARS T/O data card during taxi due to an increase in tailwind. After delaying take off for a heavy 787; we were cleared take off RWY XXR. After liftoff; I noticed what I believed to be an odor of meals cooking but that it also smelled like they were burning. Shortly after that; at around 400-500 feet AGL; I received a call from the flight attendants noting smoke in the aft cabin. I told them to standby and wait for my call back. We cleaned up the aircraft; were handed off to departures and were given climb to 16;000 feet. I repeated the clearance to ATC and requested to level off at 5000 feet mentioning that we had a technical problem. I had to query ATC a second time to get the 5000 foot level off and after that; they became aware that there was a technical aircraft problem. We configured the aircraft and I called back to the cabin to get more information from the flight attendants. They said that smoke was still present. I told them to standby and I would call back again. We were turned to a heading of 270 by ATC. I then told the First Officer that we would don the quick donning masks and run the smoke/fire or fumes procedure. The F/O remained the PF and I requested priority handling and a return to ZZZ. After consulting once more with the flight attendants a third time with great difficulty due to the masks and feedback from the ambient noise; we were informed that the smoke had reduced and that there was just a bit of haze in the aft cabin. I abandoned the smoke/fumes or fire procedure and we then turned to a heading of 180 requesting radar vectors for RWY XY knowing it was the longest runway into wind; recalling the wind had been 270 at 6 for departure. While the first officer flew; I did the Non-Routine Landing checklist and deferred the overweight landing checklist until later. I sent an ACARS message with a note that there was SMOKE IN CABIN and an ARFF (Airport Rescue and Firefighting) Yes request. I then briefed the flight attendants of a precautionary landing with time and to prepare the cabin for landing. I advised that aircraft safety vehicles would meet us. I then gave a PA to the passengers explaining the reason for our return to ZZZ and that it was due to the obvious smoke in the cabin and it was necessary for safety to return to ZZZ. I mentioned that they would see safety vehicles as we would stop on the runway for inspection and told them to remain seated with their seatbelts fastened and obey all the instructions of their cabin crew. I then took control of the aircraft as PF and assigned the First Officer the task of completing the Overweight landing checklist while I flew and spoke to ATC. As I was familiar with the Overweight landing checklist; I felt it more prudent to assign that task to the First Officer who also had set us up for an approach to RWY XY and had completed an overweight landing distance assessment. We completed all Normal and abnormal checklists that I thought were pertinent to our return and prepared for an overweight landing. I flew amethodical stable approach as I felt it was safer than racing in and becoming un-stabilized since the smoke had dissipated and the urgency reduced. We configured and captured glide slope and I disconnected the autopilot at about 500 feet ASL. I had about 850 feet per minute rates of descent on approach and landed smoothly around 2000 feet down the runway. I let auto brakes (auto brake 3) do most of the work with full reverse and disconnected the auto brakes at 65 knots bringing the aircraft to a smooth halt on the runway. I set the park brake and despite it only being a precautionary landing; I felt that it might stop an inadvertent opening by a passenger of the armed door slides if I made a PA to remain seated and did just that. We stowed the speed brakes and extended flaps to 40. We then waited for ARFF to inspect the aircraft for a heat check and any source of smoke/fire including any pooled liquids around the aircraft. They gave the 'all clear' and we waited for the vehicles to clear before vacating the runway. I briefed the cabin crew that we would taxi back to a remote bay or gate as I felt the issue was resolved once the flight attendants confirmed there was no further smoke or haze in the cabin. I briefed the passengers and then we taxied to the gate with no further incident. The two aft galley flight attendants were admitted to the hospital for observation and released. One of the flight attendants was told to stay off work for three days. After writing up the defects in the logbook; I spoke to the maintenance engineer who suspected the smoke might have been remnants of the engine wash. The smoke never got heavy but was initially thick and then turned to haze according to the flight attendants working the aft cabin. To note; the number 2 Flight Attendant position (AFT; Captain side of aircraft) ceiling near the light was the source area of the smoke/haze.We reported to sign-on at XE45 after operating a red-eye that morning resulting in a minimum rest of just under 12 hours. We were aware that the aircraft was at the airport the whole day and released to service. We were given at least three to four gate assignments and traversed the airport from one end to the other twice. By the time we pushed back; it was XI56. It seemed like there were no gates available for this aircraft and we pushed back about four hours and ten minutes after sign on. Only the First Officer ate prior to departing the airport. I chose to wait for my never to be consumed crew meal. On the decision to go against runway operations which were landing to the east and land runway XY to the west; I recalled there was a tailwind on takeoff despite all the excitement of the incident. I do believe; it might be because we were very pedantic in making multiple T/O Data Cards once we were aware of a tailwind component at the gate and then again when we made our second (greater tailwind) on the taxi out; which we remedied on the taxi way parked. This helped us go against the normal flow of traffic direction and land on the longest runway into wind. I believed it was helpful for the overweight landing at 170;000 lbs. I also think after looking back; we could have continued easterly after departure XXR and joined a right base for runway XY. This would have been a more efficient time navigational track; especially if we had a further dire situation with heavy smoke. I abandoned the smoke/fumes or fire QRH checklist after completing the QRC portion because once we were aware that the smoke had diminished; I felt we would get overwhelmed in a laboriously long checklist and I felt it was more important to get the aircraft on. This was my decision and I decided on my authority rather than become a slave to a checklist. Had the smoke occurred again; we might have actioned some of it to alleviate any electrical threats and flown high speed to the runway as time would have been even more of the essence. We were a total of about 25 minutes in flight; as this was aresult of me slowing down the processes and erroring to the side of methodical so we could deal with the overweight landing and approach preparation properly. The brand new First Officer was extremely well poised for this event and I must commend him for his assistance with the task management and well coordinated crew roles that we both exchanged. He was definitely up for the task.The biggest takeaway besides the smoke risk was the lack of clear communication using the quick donning masks. I have used them in the simulator and it does not seem as difficult as it was in the actual aircraft to speak with the cabin crew on the cabin inter phone ACP (Audio Control Panel) system. I think we should train with them on more than we do because it was the main threat to our operation besides the smoke. The cabin crew found it very hard to understand me. Perhaps it was user error; but I found it very difficult to run this cockpit with the masks on. I know this is an obvious point; as the masks are an obligatory requirement and an acceptable threat; but it really is terrible trying to run this scenario with a mask on and communicate effectively with the back. Fortunately; we were able to eventually communicate but it robbed us of some time and strained our task management and prioritization. If anyone finds after reading this report that I could have reduced that threat; please let me know as I am hoping to never don another O2 mask in the future; but if I do; I want to know how to mitigate that issue. Also; my lack of awareness that I left the intercom on also exacerbated the communications between the First Officer and I in the first few transmissions after donning the masks. The First Officer had the spare capacity to note this and brought it to my attention also turning my intercom off which preset me to NOT do that again and remember to turn it off after each transmission to him to reduce the excess background noise of breathing and other ambient noises. The priority handling call definitely reduced some of our load as ATC were great at vectoring us in a timely manner. I was always prepared to fly high speed to the runway if the smoke came back or intensified. I mention pilot currency as a causal factor due to the First Officer being so new to the aircraft and company operation. Despite that; this First Officer's previous Command and life experiences were a true asset.We believe the event may have been triggered by residual engine wash fluid. If this is the case; I believe it may help to conduct an actual test flight after engine washes or if that is considered to onerous; it may be prudent to assign someone down the back to be ready for this problem if not already a consideration. There may have been smoke or haze during the engine run-up but not detected by maintenance up front. I am interested to know what caused this issue as I would rather not go through it again; as I can imagine most pilots would attest. I know I will continue to run this event in my head for the foreseeable future to take away as much insight as possible for the next mission. Let me know what you think? Thanks for reading; and I hope this is helpful.
Second reporter narrative
We reported to a XA:30 flight from ZZZ to ZZZ1. Because of gate changes and the aircraft being towed to the gate; we ;the crew; boarded the plane around XC:30. We prepared everything for departure and pushed off the gate at XD:56. Because we knew the airplane came from MX (Maintenance) after a reported bird strike we briefed as threats - possible engine problems and/or airspeed problems from bird remains. We taxied for departure and were cleared for takeoff (FO was pilot flying). Immediately after takeoff both pilots smelled a burnt smell and shortly after the Aft FA called and reported burnt smell in the cabin and 'that it was hazy'. Around a 1000 ft we were handed off to departure control and they cleared us to climb to 16;000. We requested to stay at 5000 ft and donned our oxygen masks. CA requested priority handling and FO took over radios and kept flying the airplane using the autopilot. CA ran the Smoke fire fumes checklists while FO prepared the approach back to ZZZ. FA later called and said the cabin was clear of haze and odor. At this point the CA decided to stop the smoke fire fumes checklists and ran the non routine landing checks in order to expedite our return to the field. CA communicated with FAs; Pax (Passengers) and informed company. FO was in touch with ATC and preparing approach for ILS XY at the direction of the CA for favoring winds and longest runway. CA then took control of the aircraft and the Radios while FO ran the overweight landing checklist and briefed the approach. While on vectors from ATC CA advised ATC. FO briefed the CA on the overweight landing considerations and procedure; briefed the approach and took over the radios. We completed the descent checklist and before landing checklist and started configuring the aircraft for landing. we coordinated with ZZZ control tower that we would stop on the runway and have ARFF (Airport Rescue and Firefighting) check for heat signals. CA performed the a normal approach and overweight landing and brought the aircraft to a stop on the runway. We stowed the speed breaks and lowered the flaps to 40 incase an evacuation was required. FO talked to tower and ARFF while CA made a PA to the passengers. On a dedicated frequency; ARFF said there was no heat signal or fire; no spillage and no debris . We then took off our oxygen masks and returned to using our normal headsets. We decided we can taxi to the gate and asked ARFF to follow us to the gate. ATC gave us instructions to taxi and Ops advised us to go to gate XX. we taxied normally to the gate and performed the normal after landing and shutdown procedures. Overall time from takeoff to touchdown was 26 minutes.Since the aircraft was reported to have hit a flock of birds the day prior and had maintenance done on it to clear the birds remains; the cause for the odor and smoke was likely from a bird remain the was not cleared or from fluids used to clean the engine. When TO power was applied those probably burnt and were ingested into the PACK system. recommendation is to have a flight test after such bird strike rather than just a run up of the engines.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.