MAX 9 Door Plug Found


Investigators now have the emergency exit door plug that separated from an Alaska Airlines Boeing 737 MAX 9 over Oregon last Friday afternoon. NTSB Chair Jennifer Homendy told reporters Sunday the plug, used in place of an exit door that’s not required, was found in the backyard of a schoolteacher identified only as Bob. “We are really pleased that Bob found this,” she said. The plug should supply investigators with any missing structural data needed to determine the cause of the in-flight failure.

It turns out the aircraft was giving hints of trouble in weeks previous to the incident, which forced an emergency landing and literally sucked the shirt off the back of a young boy sitting next to the plug. At least three times since December flight deck pressurization warning lights illuminated. In each case, maintenance staff were able to clear the errors and declare the aircraft airworthy. However, the airline opted to remove the aircraft from ETOPs flights so the plane would be near an airport if the warnings triggered.

Homendy also said the crew, in addition to dealing with the depressurization, were without clear communications after their headsets were damaged. The flight deck door was also sucked open in the depressurization and was damaged when it slammed into a restroom door. Flight attendants struggled to close the flight deck door. Homendy also noted the cockpit voice recorder data had been overwritten and she renewed the NTSB’s call on the FAA to extend the mandatory recording time from the current two hours to 25 hours.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.


  1. Boeing is now claiming that it was all just a marketing stunt to introduce their new “Panoramic View” window option 🙂

  2. “However the airline opted to remove the aircraft from ETOPs flights so the plane would be near an airport if the warnings triggered” ??? ???

  3. One thing my company’s FAA PMI doesn’t want to see in maintenance logs is more than one “ could not duplicate” write up on any one item. I wonder if the “auto pressurization warning” on the 737 MAX is a MEL-able maintenance item?

  4. Reminds me of early in my career being paired with a senior Captain on a Transport category airplane. We were supposed to take the airplane on one last test flight before departing for a 3 month long assignment. The log book had several entries for a recurring snag. The last one was cleared with the notation “NFF”

    On seeing this the Captain grab the log book and stormed into the Director of Maintenance’s office and demanded to know what was up with the NFF comment. The DOM said it stood for “No Fault Found”. The Captain replied “ No, it stands for Not Fu*king Fixed ! “

    He refused to take the airplane until the problem was fixed. Eventually the maintenance guys found a frayed wire and properly fixed the snag, which never reoccurred.

    • When I was in the USAF, many years ago, we had a similar entry “MCWW”. “Malfunction Cleared While Watching”!

      • While I was in SAC, we used the acronym…. CND-FAI…. This came from the Anderson and U-Tapao Crew Chiefs (that taught us this term) following the Line Backer II missions…. Crews hated it, and I understand why…. If it’s a squawk in the serious bucket (pressurization?!?) this has to be resolved before the next flight over 13,000 Feet!

  5. Understatement of the year from NTSB Chair Jennifer Homendy after the plug was located: “We are really pleased that Bob found this.”

  6. Very fortunate it landed in a back yard and not on a busy street/shopping mall/sports ground/schoolyard or old Bob’s roof.

  7. “At least three times since December flight deck pressurization warning lights illuminated. In each case, maintenance staff were able to clear the errors and declare the aircraft airworthy.”
    Not to relieve Boeing from incompetence but this quote is confidence inspiring 🙄

  8. “Have you tried unplugging it and plugging it back in?”
    “In each case, maintenance staff were able to clear the errors and declare the aircraft airworthy.”

  9. Bertorelli, we all know you’re lurking around here. These guys are throwing out Pearls, how can you resist not chiming in? Just one little snark, c’mon man it’s in your blood!

    • I find suspicious that Paul “retired” as soon as Flying “bought” AvWeb. I cancelled Flying after 40 years.

  10. Has Boeing considered converting the Max into a jump plane?
    Jumpers wouldn’t have to overcome the anxiety of jumping — they could just be sucked out.
    Maybe they could sell few to the US Army under the “Build Back Better” program.

  11. I think I would have stuck the door in my garage and waited a few days until a reward was offered…….
    I hear they tried to find the door from geolocating the cellphones that were sucked out as well but they were all in airplane mode…….

  12. So, the airline was waiting for an accident to happen before anything was done. Look at what happened with SW flight 1380. What if that kid had been sitting in the seat next to the window? Would he have been lost out the doorway? Come on, do better. I’m a retired A&P and auto mechanic, I know the frustration of hidden problems and making repairs to alleviate the squawk. But first time, maybe, second time you need to look further, but the third time, you’re in trouble. Only difference is a car isn’t 35,000 feet in the air.

  13. Gee, you don’t have to be a plumber to realize that if it’s not holding pressure, there’s a leak somewhere. Maybe they should have called a plumber to find the leak. No one thought to pressurize the cabin on the ground and find out where the excess air is coming out.

    • The “excess air” would be assumed to be coming out one of the outflow valves and/or a ground pressurization equalization port, all of which the mechanic would need to override for your proposed test. But on the ground, the delta between the outside ambient air pressure and the cabin pressure (inside the fuselage) might not be significant enough to “leak” in a manner that is detectable. Even in a “small” airliner, the real estate to inspect involves numerous items like pressure bulkheads, line and harness fairleads, active cabin door seals, cabin window seals, etc. Ask your “plumber” to find a leak in the Empire State Building.

      What concerns me more than your “Why did you guys not find that leak?” is why there was a structural failure in that location. Loose bolts can explain the leakage at altitude, but the fact that it blew out under the pressure suggests that the plug design is defective to me. Maybe Boeing needs to rethink these loads and reconsider their design here.

  14. Granted, it would take special equipment to pressurize the cabin on the ground to the level it sees at altitude, but it doesn’t sound like rocket science. Any significant leak could probably be detected just by listening, although more sensitive methods shouldn’t be too difficult. Maybe a cabin pressurization test should be part of every major inspection. In addition to leaks they might want to be on the lookout for abnormal strains in the pressure hull.

    • My background includes finding very small leaks in vacuum systems on semiconductor equipment. We use a helium leak check which uses a mass spectrometer tuned to pick up helium this is attached to the exaust of the system then a very small amount of helium is sprayed at each connection if one leaks you see it on the leakchecker instantly. Perhaps some reworked version of this could be used to detect such faults during assembly or at annual time. I totally agree anomolies are single events that do not repeat, second occurance is BIG YELLOW FLAG not to be ignored, and any further occurrence is RED FLAG do not proceed until fault is found.
      One statement in the article bugs me, what do they mean a plug is used where an emergency exit is not required? Why not required, if it was not required build the plane without the opening! orn the explosive decompression sucks the passengers out and therfore exit door not required??

      • The aircraft is designed with enough exits for its highest capacity cabin configuration, but the customer may choose other configurations. If the exit is not needed they blank it out from the inside and do not fit the equipment the functional exit would require, saving weight and cost. To not have the provisions for that exit the aircraft would either simply not be certifiable for the extra capacity or require modification to fit an exit would have to be made. Neither are practical. There’s nothing inherently wrong with doing it this way, and it seems this was a workmanship issue not a design or structure issue.

  15. Boeing’s new motto… When one door closes, another opens… Could apply to the design team or the assembly team linked to the door plug as well…