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737MAX has a design problem that attempted to use software to cover it up. Boeing stuffed in big fans which needed to be higher to not scrape the runway. The fa

737MAX has a design problem that attempted to use software to cover it up. Boeing stuffed in big fans which needed to be higher to not scrape the runway. The fans stick out forward from the wings, which can cause the plane to pitch up. Software attempts to hide that design flaw, and pushed down really hard a couple times into the ground. Really needs a new type certification, though FAA and flying public generally don't seem to care.

nickff 4y ago
What do the issues you mention have to do with this specific airplane?
- rob74 4y ago
  The MCAS also adjusts the horizontal stabilizer, same as the trim system. So I assume if pilots see problems with the trim system on a 737 MAX, they get even more alarmed then they would on other planes...
throwawayben 4y ago
Different handling at the edge of the flight envelope is not a "design problem". The design is fine, it just handles differently from the other versions in certain regimes so they (attempted, poorly) used software to avoid that
- cjbprime 4y ago
  My understanding is that it was failing an airworthiness requirement without MCAS: https://www.law.cornell.edu/cfr/text/14/25.175 https://www.law.cornell.edu/cfr/text/14/25.175 If by "different handling" we mean "not airworthy", I wouldn't say the design is fine.
  - throwawayben 4y ago
    I believe that is false, as MCAS should (when correctly implemented) only apply at the edge of the flight envelope and those airworthiness requirements are all related to normal regimes. I can't find anything supporting your understanding
    - salawat 4y ago
      Look harder. https://aviation.stackexchange.com/questions/73132/did-boeing-need-mcas-because-the-737-max-didn-t-meet-faa-longitudinal-stability https://aviation.stackexchange.com/questions/73132/did-boein... No MCAS = does not meet the criteria to be employed in Civil Air Transport in the United States. There were several failures on the system architecture front as well, including a vulnerability to single event upset, where a cosmic ray flipping a single bit in the FC in vommand would trigger an MCAS failure state that the average civil aviation trained pilot was found not to be able to successfully cope with. It's also in the NTSB and FAA final reports, as well as several House generated investigations. I spent waaaay too many hours doing that math by hand and looking up crap on Engineering Toolbox to easily forget/forgive that.
WalterBright 4y ago
> 737MAX has a design problem that attempted to use software to cover it up. The design requirements of the software were wrong. Not the airplane, not the implementation of the software.
- himinlomax 4y ago
  Of note is that the A320 has three angle of attack sensors, while the MAX only has one -- no redundancy.
  - tallanvor 4y ago
    That's not true. The MAX always had two sensors, it's just that the software design only ever used one of them at a time.
    - theGnuMe 4y ago
      Man imagine being on that development team. I wonder if anyone thought it was a bad requirement at the time and whose job it was to identify that (and was the issue flagged and if not why not). A programmer isn’t an aeronautical engineer but it really says how a whole systems view is necessary. I work in a field with increased specialization but we build systems and sometimes similar things come up. There are few who see the end to end system for itself. I imagine rockets and the space shuttle get that level of scrutiny and that books have been written about it.
      - salawat 4y ago
        They knew a dual/multi-sensor system would be required. They aldo knew putting one in would have mandated simulator training; and they had to avoid that at all costs. That's why the MAX accidents are so notably engineering failures; the industry knew what needed to be engineered, but business shot it down, and forced them to build something fundamentally unsafe in the interests of maximizing profit, and not sweating the product in the box.
    - himinlomax 4y ago

nickff 4y ago

What do the issues you mention have to do with this specific airplane?

rob74 4y ago
The MCAS also adjusts the horizontal stabilizer, same as the trim system. So I assume if pilots see problems with the trim system on a 737 MAX, they get even more alarmed then they would on other planes...

throwawayben 4y ago

Different handling at the edge of the flight envelope is not a "design problem". The design is fine, it just handles differently from the other versions in certain regimes so they (attempted, poorly) used software to avoid that

cjbprime 4y ago
My understanding is that it was failing an airworthiness requirement without MCAS: https://www.law.cornell.edu/cfr/text/14/25.175 https://www.law.cornell.edu/cfr/text/14/25.175 If by "different handling" we mean "not airworthy", I wouldn't say the design is fine.
- throwawayben 4y ago
  I believe that is false, as MCAS should (when correctly implemented) only apply at the edge of the flight envelope and those airworthiness requirements are all related to normal regimes. I can't find anything supporting your understanding
  - salawat 4y ago
    Look harder. https://aviation.stackexchange.com/questions/73132/did-boeing-need-mcas-because-the-737-max-didn-t-meet-faa-longitudinal-stability https://aviation.stackexchange.com/questions/73132/did-boein... No MCAS = does not meet the criteria to be employed in Civil Air Transport in the United States. There were several failures on the system architecture front as well, including a vulnerability to single event upset, where a cosmic ray flipping a single bit in the FC in vommand would trigger an MCAS failure state that the average civil aviation trained pilot was found not to be able to successfully cope with. It's also in the NTSB and FAA final reports, as well as several House generated investigations. I spent waaaay too many hours doing that math by hand and looking up crap on Engineering Toolbox to easily forget/forgive that.

WalterBright 4y ago

> 737MAX has a design problem that attempted to use software to cover it up. The design requirements of the software were wrong. Not the airplane, not the implementation of the software.

himinlomax 4y ago
Of note is that the A320 has three angle of attack sensors, while the MAX only has one -- no redundancy.
- tallanvor 4y ago
  That's not true. The MAX always had two sensors, it's just that the software design only ever used one of them at a time.
  - theGnuMe 4y ago
    Man imagine being on that development team. I wonder if anyone thought it was a bad requirement at the time and whose job it was to identify that (and was the issue flagged and if not why not). A programmer isn’t an aeronautical engineer but it really says how a whole systems view is necessary. I work in a field with increased specialization but we build systems and sometimes similar things come up. There are few who see the end to end system for itself. I imagine rockets and the space shuttle get that level of scrutiny and that books have been written about it.
    - salawat 4y ago
      They knew a dual/multi-sensor system would be required. They aldo knew putting one in would have mandated simulator training; and they had to avoid that at all costs. That's why the MAX accidents are so notably engineering failures; the industry knew what needed to be engineered, but business shot it down, and forced them to build something fundamentally unsafe in the interests of maximizing profit, and not sweating the product in the box.
  - himinlomax 4y ago