Leeham News

Also everyone is futzing with business models. There are maintenance facilities from many companies all over the world that can work on airframes, engines etc. The airframe and engine manufacturers are seeing all this post-sale income go to those companies, and not back to the manufacturer. So they are "fixing" that. For example Rolls Royce does "power by the hour" where the airline is essentially paying rent on the engine while it is in use. That means Rolls takes care of the maintenance etc (all rolled into the per hour price). There are far fewer Rolls locations that can do that work. Then suddenly a lot of maintenance work needs to be done, and planes have to wait. For those interested in aviation, I recommend following leehamnews[1]. The industry is very similar to what is faced in the software industry but over far larger timescales. eg airframe manufacturers have constant streams of improvements, but have to work out if and how to charge for them, how to do deal with existing aircraft of the same model without them ("backwards compatibility"), and the constant spending money to make money. You even see second system effects (arguably the birth of the 787 was just that financially, manufacturing and technically). [1] https://leehamnews.com

A pattern has been identified: A company that has sound procedures and doesn't follow them. Read https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… and search for CMES and SAT.

The report seems to mesh with and confirm many details of the anonymous insider account at https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… The bolts were not reinstalled following work on the plug rivets/seal. The official system doesn't record that work was done requiring the bolts to be removed.

"The automatic trim we described last week has a name, MCAS, or Maneuvering Characteristics Automation System. It’s unique to the MAX because the 737 MAX no longer has the docile pitch characteristics of the 737NG at high Angles Of Attack (AOA). This is caused by the larger engine nacelles covering the higher bypass LEAP-1B engines." Boeing only told pilots MCAS existed following the Lion crash, almost 18 months after the plane entered service https://leehamnews.com/2018/11/14/boeings-automatic-trim-for-the-737-m…

This thoroughly vindicates what the anonymous whistleblower on the internet was saying: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… > Current Boeing employee here – I will save you waiting two years for the NTSB report to come out and give it to you for free: the reason the door blew off is stated in black and white in Boeings own records. It is also very, very stupid and speaks volumes about the quality culture at certain portions of the business. > A couple of things to cover before we begin: > Q1) Why should we believe you? A) You shouldn’t, I’m some random throwaway account, do your own due diligence. Others who work at Boeing can verify what I say is true, but all I ask is you consider the following based on its own merits. > Q2) Why are you doing this? A) Because there are many cultures at Boeing, and while the executive culture may be throughly compromised since we were bought by McD, there are many other people who still push for a quality product with cutting edge design. My hope is that this is the wake up call that finally forces the Board to take decisive action, and remove the executives that are resisting the necessary cultural changes to return to a company that values safety and quality above schedule. [...] > However, more critical for purposes of the accident investigation, the pressure seal is unsurprisingly sandwiched between the plug and the fuselage, and you cannot replace it…

> Turning it off with the STAB TRIM CUTOFF switch turned it off. > The pilots in the second crash did not follow that procedure. "At 05:40:35, the First-Officer called out 'stab trim cut-out' two times. Captain agreed and First-Officer confirmed stab trim cut-out."[1] However they were unable to correct the trim of the aircraft without the help of the electrical systems (still being on full takeoff power didn't help) and continued losing altitude. So around 3 minutes later STAB TRIM cutout was switched back to normal. Pretty much the moment they did that the aircraft pitched down hard, the situation becoming unrecoverable within seconds, followed by the aircraft impacting the ground. There were possibly ways to save the aircraft (reduce aerodynamic forces that prevented trim by hand by, for instance, reducing thrust), but those weren't detailed in any ADs and probably won't be the first thing on pilot's minds in a situation like that. [1]https://leehamnews.com/wp-content/uploads/2019/04/Preliminary-Report-B…

As someone who has actually flown on the Concorde, I can say that I'd gladly endure its tight seats again and empty my wallet in exchange for a shorter flight. Heck, if I had the option between spending $20,000 for a NY-London roundtrip on an Overture (the same price for that route on the Concorde, inflation-adjusted) versus spending $20,000 to charter a long-range private jet (likely a significant underestimate), I'd go for the Overture in most cases. However, although I'm rooting for any company that's making a sincere (as opposed to fraudulent) attempt at bringing back supersonic travel, the hardest challenges may still be ahead for Boom. The biggest one is the need to find or build a new engine. They've recently redesigned the Overture to use four engines instead of two, which should ease required engine specs, but there's no engine that would meet the reliability, noise, fuel consumption, and dimension requirements for a supersonic passenger aircraft. Related to the engines: money. It sounds impressive that boom raised at least $150 million, including $60 million from the US Air Force (which has the added advantage of creating a new customer segment in the military)... until you learn engine development alone would require in the ballpark of $6 BILLION of capital. Aviation history is rife with examples of amazing, innovative aircraft designs that failed because no suitable engine was available. Also, Boom leadership has set some ambitious goals, which makes me a bit…

It's been reported that an FAA analysis after the first crash concluded that - without modification - MCAS was expected to cause an additional 15 crashes over the service life of the 737 MAX. It seems that when the second aircraft crashed Boeing was already working on a new version of MCAS, but they and the FAA decided to keep this quiet and keep the aircraft flying. I think that this decision accepted rather a lot of risk to life, compared to what I would expect from civil aviation. "Peter Defazio, the chairman of the House Transportation Committee, said an FAA analysis following the Lion Air accident but before the Ethiopian Airlines crash concluded there would be 15 fatal MAX accidents if there was no fix to MCAS. DeFazio asked Dickson why wasn’t airplane grounded then? He did not have an answer." https://leehamnews.com/2019/12/11/faa-no-max-certification-until-2020-… (I think the first report was in the WSJ, but that's behind a paywall)

Ironically, I believe that your information is also inaccurate. MCAS is required in order to meet federal airworthiness requirements. Without it, in certain flight conditions the back-pressure on the control yoke gets less as the yoke is pulled further back. It's like over-steer in a car, and is simply not allowed. Yes, the plane is dynamically stable; if you leave the yoke in one position it won't pitch up even more. However, the forces must be corrected somehow, regardless of type rating concerns. "The 737 MAX was a bit too easy to pull into a stall when flying with high AoA and making abrupt maneuvers. The larger engines for the MAX hung further forward from the wing, added a destabilizing aerodynamic area ahead of the center of gravity, destabilizing the pitch moment curve at high AoA. Boeing and the certification authority, FAA, decided added margins was called for. Boeing added a pitch augmentation at high AoA called Maneuvering Characteristics Augmentation System, MCAS. The aircraft should trim nose down to increase the stick force needed once it passed into the light grey area where the base aircraft had a region of less stability. Before the augmentation, the pilot felt if the aircraft wanted to fly into the stall, it got easier to increase the AoA after 12°AoA. With the augmentation the felt extra force was the same for the first and last part of the curve before the maximum lift was achieved at stall (and stall warning kicked in)." [0] The manner of the fix…

Reading a lot of detailed reports, I concluded that nobody at Boeing ever properly tested the conditions that happened by both Lion Air and Ethiopian, until much after the second crash. Boeing didn't do enough steps to reconstruct what happened by Lion Air, otherwise they would have never published totally useless procedure which was then followed by the pilots of Ethiopian. The actual testing in the proper simulator would have shown that the emergency procedure, as written by Boeing after Lion Air crash, just can't work. The pilots in Ethiopian and all the passengers paid with their lives for a whole world to learn that. The world knows because one pilot tried to partially reconstruct the conditions on his own in an older simulator, as there were effectively almost no new simulators because the Boeing's selling point was that the new model of the plane is same as an old one model, just to avoid the recertification and pilot retraining. So the said pilot did the test for youtube, showed that what the pilots probably did matched the emergency procedure, and that exactly that following the procedure most probably results in the crash, but had to remove the video once his employer became aware of what he did. I've posted the link to that original source then, but HN moderators marked it then as a "dupe": https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-s…

"All of the above" The MCAS itself did exactly what it was programmed to do. One of the sensors feeding it, which was not redundant (!), malfunctioned, and MCAS acted on the data - garbage in, garbage out. By not having sufficient redundancy, MCAS was designed in a failure-prone way. This was justified because the failure would be like another kind of known failure mode (runaway trim), and pilots already had a checklist for it (the key point being to turn off electric trim). The problems with that are: 1. The problem a malfunctioning MCAS (acting "correctly" based on bad data) introduces is intermittent/erratic, making it harder to correctly react to it. Especially since the pilots weren't aware that a system that would act like this was on board! 2. Humans make mistakes in high-stress situations, which is why accepting something that introduces additional problems and relies on humans to handle them is a bad idea. 3. Turning off the electric trim also made it hard for the pilots to correct the situation, as it disables the manually-controlled but motor-powered trim. One theory is that the forces may have been too great for the backup solution (trimming manually) to work, a situation that old (but not current) manuals addressed. MCAS has a limit how much it will trim, but any trim input by the pilot resets it, and lets it move the trim by the limit amount again. This is just a layman's interpretation: From the flight data recorder, it seems like the Ethiopian ET302…

Prior to MCAS, most causes of trim runaway could be stopped by countermanding it with the control column, but, because MCAS is intended to avoid a pilot-commanded (though presumably accidental) stall, this is not the case for MCAS: "[MCAS intervention] can be stopped by the pilot counter-trimming on the yoke or by him hitting the CUTOUT switches on the center pedestal. It’s not stopped by the pilot pulling the yoke, which for normal trim from the autopilot or runaway manual trim triggers trim hold sensors. This would negate why MCAS was implemented, the pilot pulling so hard on the yoke that the aircraft is flying close to stall." [1] [my emphasis.] So it seems we may have several issues here: 1) Prior to MCAS, trim stab cutout was almost the last-ditch option against trim runaway (there was one more: grab the trim wheels and physically prevent it), but it became the only way to deal with an MCAS-commanded runaway (other than grabbing the trim wheel.) 2) Boeing did not reveal this prior to the inquiry into the Lion Air crash, despite the fact that it introduced a new experience of trim runaway that differed from what pilots had been trained to expect. 3) The Boeing / FAA response to the Lion Air inquiry was an Airworthiness Directive that basically said "pay attention to what we said before about handling trim runaway" (though, whether or not Boeing / FAA made a point of it, pilots may well have become aware of how MCAS runaway differed from their prior training -- that…

Eh, slightly faulty memory on the details, but it's here: Part 1 - https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… Part 2 - https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… Still a clusterfuck all around though.

It's an anonymous comment posted here: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… . It was posted before any official information was released and seems to track with information that was subsequently released.

Search for that user in the comments here; https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

The Boeing guy who posted the detailed history of the plane a few weeks ago[1] said something to the effect that they discussed things in a slack-like system rather than enter in the official records system because managers would get upset at KPIs not being met. [1] https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

> the guy at the bottom who signed off the bolt work without even looking at the plane, which is criminal Rumour is [1] bolt removal was entered in the tracking system as 'opening' the door rather than 'removing' the door and hence it didn't attract a re-inspection. [1] https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

According to the "insider source", 392 non-conforming defects in the fuselage door installation in the last 365 calendar days. > As a result, this check job that should find minimal defects has in the past 365 calendar days recorded 392 nonconforming findings on 737 mid fuselage door installations (so both actual doors for the high density configs, and plugs like the one that blew out). That is a hideously high and very alarming number, and if our quality system on 737 was healthy, it would have stopped the line and driven the issue back to supplier after the first few instances. Source: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

As things stand, it seems the anon insider report from 3 weeks back was legitimate and accurate, and holds answers to your question: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

I thought the whistleblower comments linked from the article were especially interesting. Relinking here: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

Whistleblower comments mentioned in piece: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe… https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

Sounds a lot like the NYT got a hold of the anon Boeing employee commenter from last week, and verified their employment and story. In case anyone missed the multiple duplicate HN postings from this person's comments- https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

This apparent anonymous comment from a Boeing employee about the number of issues happening in their qaulity system is a bit worrying: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

Original source: https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspe…

Tell that to Boeing[0] [0]https://leehamnews.com/2019/09/30/boeings-737-in-another-pickle/

There was actually a test with Southwest Airlines line pilots, and it took them a minute to get to the stab trim cutout in response to this issue. https://www.commerce.senate.gov/services/files/3BBE2CD5-AE41-4048-9C50… The Ethiopian Airlines pilots did get to the stab trim cutout as well (probably because they had read the emergency directive Boeing sent out) but were unable to manually trim afterwards due to the forces involved - had they cut airspeed at the start they probably would have been able to do so, but that was not part of the instructions at the time. For an analysis of the situation they were in, see https://leehamnews.com/2019/04/05/bjorns-corner-et302-crash-report-the…

LNA, an aviation industry newsletter, recently came to a very different conclusion [1]. The biggest difference to Wendover Productions's numbers is a hugely higher estimate in the cost of replacing the battery every 5-10 years due to battery degradation. [1] https://leehamnews.com/2021/07/01/the-true-cost-of-electric-aircraft/

The MAX does have flattened cowlings, though the effect is less pronounced than on the NG. Compare the MAX (right) to the completely round cowling on the A320neo's LEAP-1A: https://leehamnews.com/wp-content/uploads/2020/11/737NG-vs-MAX-nacelle… https://aerocorner.com/wp-content/uploads/2020/01/Aegean-Airbus-A320ne…

That Charleston plant has terrible quality control compared to the more mature, unionized group in Everett. Some airlines have refused shipments from south Carolina in preference to the Washington group. https://leehamnews.com/2020/09/14/pontifications-boeing-sc-makes-its-c…

This site has some more info about the 777 etc. Some articles may be paywalled though. https://leehamnews.com/2020/01/25/third-time-is-the-charm-777x-takes-t…