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Boeing 737 MAX problems

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I think we can agree to disagree on this gowler!  I can be pissed at some things Boeing or even the FAA did without overdoing it. Some of us more aviation minded people (I'm including you here too) have knowledge about all sorts of accidents, and can put things in more perspective.

People didn't stop flying Airbus because two A320's flew into the water with pilots putting in opposing stick inputs (or at least losing any semblance of cooperation) after losing situational awareness after systems failures and then mishandling those systems. (Air France 447, AirAsia 8501, although 5 years apart).  It has long been a question about how good it is to have two non-connected sidesticks that can go in opposite directions, losing visual and force feedback between the two pilots both applying controls. It usually works but has its issues.

Even if I discount your doomsday scenario, I'm probably being too rational and you have a better insight into people being irrational idiots spooked by shiny things, that happened close enough together in time that they remember both at once...

 

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You may be correct. There is a ton of money and prestige involved. But my prediction of the effect is still the same so far. The blame game is just beginning and wil soon gather momentum. 

I am far from qualified to judge whether or not software is a good enough fix, or to what extent the modification of the engine placement has affected the aircraft’s stability. But I’m pretty sure Boeing should not have been too cheap to cut corners in such a massive way.

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12 hours ago, gowlerk said:

Exactly, how many lost aircraft are acceptable? Everyone in the industry, including the regulators know that incidents will be rare. That is not really good enough. The cat is out of the bag, the barn door is open and the cows are in the corn, the foxes are in the hen house. Boeing is going to have to shut down the 737 Max program. Probably by this summer. It will be "temporary" until it becomes permanent. There are other aircraft available to fill the market niche. But they can't be produced fast enough to meet the demand. Boeing will move resources to increasing the production of the model before the Max and they will have to sell them at a reduced price while they redesign the Max into a new product with a different name. Of course, that will take the better part of a decade.

 

Or maybe I'm completely wrong. But I just can't see the airlines accepting a product that the public won't want to fly on.

I tend to be a bit cynical about this sort of thing. Maybe more than 'just a bit.'

Boeing is too big. Too important. Too many jobs, too much taxes, too many 'friendly' congresscritters.


I can see this getting fixed, and I can see the public accepting it. 

 

Increase the number of sensors. Rewrite the code, making it harder for the computer to get 'confused'. Make it much easier to override and shut off the computer's input. 

 

In the end, this is a case of (computer generated) runaway trim. That's been a known issue ever since electric trim was invented. I think they will be able to get past it.

Besides, it's not like the accidents were here in the US. 

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14 hours ago, gowlerk said:

Or maybe I'm completely wrong. But I just can't see the airlines accepting a product that the public won't want to fly on.

They won't.  But don't overestimate the attention span of the public.

Next week: "I won't fly on a 737!  They're dangerous."  Airline: "No, that's only the 737 MAX. We've been flying the 737 for 20 years."

In one month: "Which was the airplane we're not supposed to be flying on?  The Maximum or something?"

In six months: "Oh, did they ever fix Boeing?  They must have and this is a really good deal!"

In 12 months: "Wow did you hear that Airbus just crashed?  I'm never flying on one of those again!  They're unsafe."

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I could see a possibility of that happening. A lot depends on just how unstable that engine placement really is. Only Boeing really understands that right now, but it will be heavily scrutinized. The last time they had a large grounding it was lithium batteries that needed better containment. That's a fixable problem. They will have to convince the regulators that software will fix this problem and that turning off the MCAS does not present a large danger. Now that it's grounded there needs to be a justification for returning it to service. That's why Boeing fought so hard against grounding it. The regulators are going to be under immense pressure from all sides. But they will surely understand that if they now give the aircraft a green light, and then another one is lost, it will be very bad for them. It is also possible, but unlikely, that Boeing itself will decide it's own best interest lies in going further than a software update.

Likely 100s of Billions are on the line either way. Boeing's stock is down another 2% on the day right now while the indexes are up a little. But it's still up for a one year period. I'm not buying yet.

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I somewhat doubt that even Boeing fully understands the stability issue. 

Or how to fix it. 

The axis of thrust was moved. That has all sorts of consequences. 
The level of testing required to understand all of them is pretty large. 

I'm guessing that they picked the simplest/easiest/cheapest way to fix what they understood. 

 

It may turn out that a more complex fix is needed. One option would be to include a power reduction sequence into the 'self correction' in addition to the trim change. 
It may turn out that there just need to be a few more sensors and some programming adjustments (increase redundancy). 

I'm going to guess that whatever fix is decided on, they're going to make sure the pilots are aware of it this time.

Considering that the MCAS was not originally included in the operating manual, it's not super surprising that the pilots in the first crash didn't fix the problem. They likely didn't know what was going on or why.

Short article that covers a bit of the system: https://theaircurrent.com/aviation-safety/what-is-the-boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/

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Seattle Times: Flawed analysis, failed oversight: How Boeing, FAA certified the suspect 737 MAX flight control system

https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/

The safety analysis:

- Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.

- Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.

- Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.

 

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I think one thing that is going to cause trouble for Boeing is not only that there were two crashes, but were a great many cases where the system "ran away" and was caught in time by pilots - who either managed to shut down the trim system or were able to continue flying by constantly inputting nose-up trim.  Many of them ended up in the ASRS database (FAA's "report bad stuff and you won't get in trouble" system) which is available to Boeing - and it's likely that Boeing has more such reports from its own testing.

In Washington, a grand jury is starting to look into the issue, which is not good news for Boeing.  There is some suggestion that they are looking at what shortcuts they were allowed to take in order to better compete with foreign companies (like Airbus.)

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5 hours ago, ryoder said:

Bloomberg: Pilot Who Hitched a Ride Saved Lion Air 737 Day Before Deadly Crash

https://www.bloomberg.com/news/articles/2019-03-19/how-an-extra-man-in-cockpit-saved-a-737-max-that-later-crashed

You've got to wonder how the hell a plane that was out of control due to a systems malfunction and required intervention by a passenger can be flying again the next day with a full load of passengers. 

 

"The FAA last week said it planned to mandate changes in the system to make it less likely to activate when there is no emergency. The agency and Boeing said they are also going to require additional training and references to it in flight manuals."

 

Awesome. Another cludge.

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These type of accidents, that are preventable by comprehensive systems knowledge, wide range of real World experience and adequate training are likely to increase as pilot proficiency becomes more about computer management than physical hands on flying. Even after these two tragic crashes every Airline jet flying is incredibly well engineered and safe even in the hands of mediocre crews as shown by the safety statistics. Having flown hundreds of acceptance test flights as PIC in Boeing, Airbus and McDonnell- Douglas aircraft as well as being the observation pilot on these types of flights performed by Airline crews from all over the World,  the biggest issue I see is over reliance on automation and lack of general system knowledge. When you couple this with crews that have never experienced a real inflight issue due to the reliability of modern aircraft and often their too quick intro to the right seat of a jet airliner after only 200 hours or so of strictly structured flying it's actually a wonder there are not more accidents, which just emphasizes the safety of modern aircraft, including the MAX.  This is not to say that the Max problems don't need to be addressed but as they say hind sight is always 20/20, it is very possible  Boeing and the FAA  could not have foreseen this sequence of events and lack of crew ability to deal with it, when or if it occurred. So before jumping on the bashing Boeing or the FAA bandwagon lets see what the final outcome of the investigations are and what Boeing will do to correct any problems. With all the above  being said I do think that both Boeing and the FAA were very laggardly in grounding the aircraft until the problem could be understood and fully addressed. As an aside -- yes you can disable the trim systems by flipping two stab trim switches on the aft of the center console , and this was emphasized on every recurrent course I ever took, which were many.

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6 minutes ago, ndege said:

  the biggest issue I see is over reliance on automation and lack of general system knowledge. When you couple this with crews that have never experienced a real inflight issue due to the reliability of modern aircraft and often their too quick intro to the right seat of a jet airliner after only 200 hours or so of strictly structured flying it's actually a wonder there are not more accidents, which just emphasizes the safety of modern aircraft, including the MAX

Definitely agree there.  But until recently that was more a problem for Airbus aircraft than Boeing, because often the pilot is pretty far removed from what the airplane is doing on the Airbus fly by wire system.  (Air France 447 is a good example here.)  There's an old meme that "what's it doing now?" is the most often overheard question in Airbus cockpits.  Up until recently that wasn't an issue in Boeings.

Quote

it is very possible  Boeing and the FAA  could not have foreseen this sequence of events and lack of crew ability to deal with it, when or if it occurred.

It might have been possible to be unaware of that before October, but it would be hard to make a case for them not being aware of it after that.  To their credit they did publish an AD a few weeks later.

Quote

As an aside -- yes you can disable the trim systems by flipping two stab trim switches on the aft of the center console , and this was emphasized on every recurrent course I ever took, which were many.

And 99 out of 100 pilots would likely have no problem doing that.

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16 minutes ago, ndege said:

These type of accidents, that are preventable by comprehensive systems knowledge, wide range of real World experience and adequate training are likely to increase as pilot proficiency becomes more about computer management than physical hands on flying. Even after these two tragic crashes every Airline jet flying is incredibly well engineered and safe even in the hands of mediocre crews as shown by the safety statistics. Having flown hundreds of acceptance test flights as PIC in Boeing, Airbus and McDonnell- Douglas aircraft as well as being the observation pilot on these types of flights performed by Airline crews from all over the World,  the biggest issue I see is over reliance on automation and lack of general system knowledge. When you couple this with crews that have never experienced a real inflight issue due to the reliability of modern aircraft and often their too quick intro to the right seat of a jet airliner after only 200 hours or so of strictly structured flying it's actually a wonder there are not more accidents, which just emphasizes the safety of modern aircraft, including the MAX.  This is not to say that the Max problems don't need to be addressed but as they say hind sight is always 20/20, it is very possible  Boeing and the FAA  could not have foreseen this sequence of events and lack of crew ability to deal with it, when or if it occurred. So before jumping on the bashing Boeing or the FAA bandwagon lets see what the final outcome of the investigations are and what Boeing will do to correct any problems. With all the above  being said I do think that both Boeing and the FAA were very laggardly in grounding the aircraft until the problem could be understood and fully addressed. As an aside -- yes you can disable the trim systems by flipping two stab trim switches on the aft of the center console , and this was emphasized on every recurrent course I ever took, which were many.

It's great to see a professional perspective on this. It leads me to ask your opinion on what you would consider to be the root cause of these accidents, given what is known so far. Is it lack of training and/or poorly implemented software? Or does it go further into the design compromise of moving the engine mounts? As a pilot are you OK with Boeing's decision to just use software to counteract the bad effects of moving the engines or do you feel a deeper more expensive re-design should have been done?

My feeling is that too many compromises were made in the rush to get an aircraft certified to keep up with the competition. But I have absolutely no qualifications to judge. I doubt that you are in a position to completely know the answer either. But I'd still like to know your feelings on the matter.

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Without knowing the actual specifics and the findings from the Black boxes and voice recorders it's just speculation on my part. My best guess is, especially considering that some US crews apparently experienced this issue without crashing, that the root cause of the accidents were the crews lack of significant systems knowledge, lack of wide experience and inexperience in hand flying the aircraft, which causes them to try and correct problems using the automation as they are in many instances afraid of taking command manually. No doubt a contributing factor was that the MCAS system relied on input from only one source and was able to activate by an erroneous input without a crosscheck reference. This is probably where the fix will occur. If this system operates correctly and the aircraft was flown within normal limits it would never activate, so I have no issues with Boeing's decision to install software as a back up. All large jet aircraft have multiple limitations, overspeed, underspeed etc. which if the aircraft is flown beyond the automation will try and correct by flight control and/or engine inputs - so this is not an uncommon situation.

Personally I would have loved to see Boeing design a mini 787 to replace the 737,  maybe that will be next.

Virtually all training today, as I'm sure you know, is done in simulators which provide a wonderful training experience, much better than you could manage in the actual aircraft, but only a very small portion of the entire training is taken up with hand flying and removing the automation, many times in the sim I have been criticized for not using the autopilot enough. The crash of the Airbus 330 in the South Atlantic a few years ago was another example of over reliance on automation, lack of rounded experience and poor manual flying skills. The crash of the B777 in San Francisco in perfect weather is another example of lack of basic flying skill and fear of hand flying .Hopefully the training will in future include more manual flying time, along with automation which when correctly used is invaluable. 

I have no knowledge of the design implementation so can't comment if the project was pushed through too quickly, but seriously doubt there was ever major safety compromises made by  Boeing and/or the FAA to facilitate the delivery schedule.

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(edited)
13 hours ago, ndege said:

No doubt a contributing factor was that the MCAS system relied on input from only one source and was able to activate by an erroneous input without a crosscheck reference. This is probably where the fix will occur. If this system operates correctly and the aircraft was flown within normal limits it would never activate, so I have no issues with Boeing's decision to install software as a back up. All large jet aircraft have multiple limitations, overspeed, underspeed etc. which if the aircraft is flown beyond the automation will try and correct by flight control and/or engine inputs - so this is not an uncommon situation.

The single-source input to a flight control system was my first thought about this situation.  We're pretty new here (Cessna) to stick pusher design and implementation, but all of our systems have multiple AOA vanes with constant monitoring.  A single vane measuring near the critical AOA can and will fire the stick shaker on that side only, but it takes both vanes meeting the pusher criteria to initiate a push.  Any miscompare between the vanes flags a CAS message to the crew and the pusher system is disabled entirely.  Also the typical AP disconnect button on both yokes will disable the pusher system.  There are plenty of system safety design reviews and failure analysis reports done on these systems, and they are well within the regulated 10^-9 reliability requirements, but at the end of the day it's better to not have automatic flight control input than to have it fire at an inopportune time.

I think that's where the fix would occur as well, but it's still no easy venture.  The software implementation to incorporate a second source and associated logic is still quite a bit of work on smaller simpler jets.  If they decide to add a new AOA vane, there's flight testing for AOA strapping and local-to-body AOA adjustments.  And depending where it's added, there could be enough airflow distruption so that air data calibration and RVSM certification need redone as well.

Edited by linebckr83

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(edited)

NYT:  Doomed Boeing Jets Lacked 2 Safety Features That Company Sold Only as Extras
https://www.nytimes.com/2019/03/21/business/boeing-safety-features-charge.html

Boeing’s optional safety features, in part, could have helped the pilots detect any erroneous readings.  One of the optional upgrades, the angle of attack indicator, displays the readings of the two sensors.  The other, called a disagree light, is activated if those sensors are at odds with one another.

Edited by ryoder

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Reuters: Ethiopia crash captain did not train on airline's MAX simulator: source

https://www.reuters.com/article/us-ethiopia-airplane-simulator-exclusive/exclusive-ethiopian-crash-captain-untrained-on-737-max-simulator-idUSKCN1R20WD

“Boeing did not send manuals on MCAS,” the Ethiopian Airlines pilot told Reuters in a hotel lobby, declining to give his name as staff have been told not to speak in public.

“Actually we know more about the MCAS system from the media than from Boeing.”

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(edited)
1 hour ago, linebckr83 said:

I think that's where the fix would occur as well, but it's still no easy venture.  The software implementation to incorporate a second source and associated logic is still quite a bit of work on smaller simpler jets.  If they decide to add a new AOA vane,

Nice to have someone from industry comment. I think though that the 737 Max does have an AOA vane already on each side, used to drive left and right side display systems in some way in addition to the left and right side pitot tubes. Think that is standard and not an option but not absolutely sure. But the MCAS was tacked on using only one side's AOA vane. [Edit: Ryoder's link also gets at the issue of comparing data from the 2 sensors.]

At least already having 2 vanes already should help speed the fix -- as you talked about, with 2 inputs one can at least put up a big warning when they disagree, even if it doesn't help with deciding which data is bad, as one might with 3 inputs.

Edited by pchapman

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14 hours ago, ndege said:

 especially considering that some US crews apparently experienced this issue without crashing,

Just a brief comment to add to your good post.  I've heard the above on the news too but I've started to get the impression that that was mainly overeager reporting by unknowing media. For all I know MAYBE there were cases, but some of the "control problems" the media discovered from the NASA ASRS confidential incident reporting system (I guess) were unrelated to MCAS. If a pilot had some finger trouble with autopilot settings and accidentally busted an assigned altitude, it doesn't necessarily make it the airplane's fault.

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1 hour ago, pchapman said:

Just a brief comment to add to your good post.  I've heard the above on the news too but I've started to get the impression that that was mainly overeager reporting by unknowing media. For all I know MAYBE there were cases, but some of the "control problems" the media discovered from the NASA ASRS confidential incident reporting system (I guess) were unrelated to MCAS. If a pilot had some finger trouble with autopilot settings and accidentally busted an assigned altitude, it doesn't necessarily make it the airplane's fault.

I took a look at the ASRS records (helpfully reproduced here: https://www.theatlantic.com/notes/2019/03/heres-what-was-on-the-record-about-problems-with-the-737-max/584791/ by the Atlantic) and I didn't see any MCAS specific runaway trim problems.  There was:

- Two nose-down incidents while on autopilot - however, disconnecting the autopilot resolved the problem, suggesting it was not the MCAS problem (which is not disabled when the autopilot is)

- Two reports of poor training for the MAX.  (No in-air incident.)

- One report of lack of MCAS documentation. (No in-air incident.)

- One failure of autothrottles, remedied by manually positioning the throttles.

Of course not everything gets reported to ASRS; there are likely a lot more squawks recorded by airlines than appear in the ASRS.

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22 minutes ago, DJL said:

I can't believe that the fact that they were almost killed in that airplane didn't make the rounds.

That's why maintenance squawk systems exist - because such things are so often overlooked.  Even big issues like that.

Keep in mind that afterwards both pilots were likely kicking themselves.  "Holy shit!  I can't believe I missed that!  I'm going to write it up, go home, and hope none of the other pilots find out how much I suck.  I really need this job."

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The first airline cancellation of orders for the aircraft has been announced. It's only a small airline that I've never heard of and it's only for 50 copies. That's probably not enough to start a cascade. But they are claiming their passengers will not fly in it. This will start to put pressure on other airlines to follow suit.

 

https://www.cnn.com/2019/03/22/business/boeing-737-max-garuda-cancel/index.html

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The Max10 is already in its certification process and it is expected to have all these issues plus a few more. So my guess is that Boeing will wind down production of the Max8, push forward the new certification of the Max10 with these issues resolved and have a few differences in there too and then will as a show of goodwill will toss in the upgrades and optional items to trick the planes out with everything for any of the existing Max8 orders that want to convert.

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