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  • Originally posted by Evan View Post
    I don't think FADEC is a perfect metaphor for flight control systems. There are fewer interdependencies and thus fewer failure ramifications..
    And that's where the added complexity of the systems and their integration and, communication and interaction (which again adds a lot of complexity) comes into play.
    The FADEC has been FA and D since the 70's if I am not mistaken, So we are 40 years ahead of that with the technology. The reliability, speed, capability and memory capacity of the electronics has multiplied many-times-fold since then.

    I have no doubt that the technology and engineering capacity exist TODAY (or 10 years ago) to make it happen.
    I suspect that it did not happen mostly because or regulatory burden and liability issues (if the pilot f-up in a reasonable good design, we will not be liable, if the computer kills everybody on board because of a design or reliability issue we will be liable, even if that happens 1/100th of the times that everybody dies because a pilot f-ups in situations where this technology would have saved the day).
    But there is a point where the steep needs to be taken, An I think that we are reaching this point.

    Again, I'm not suggesting that we need to add complexity that allows pilots to start reconfiguring systems in flight beyond what is necessary. I'm just pointing out that, when the systems are designed to reconfigure, the pilots need to know (or have quick reference to) all the ramifications of those reconfigurations.
    The thing is that we need to add complexity behind the scene to get a simple user interface and a better self-enclosed robust solution. The reconfiguration should have no ramifications other than the added risk because you lost some redundancy. Just like in a multiple-channel FADEC.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

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    • Originally posted by Evan View Post
      On the A320, when you lose FADEC, you lose N1 and N2 limit protections. You lose automated control of engine thrust ratings. You lose automated acceleration and deceleration scheduling. You lose bleed valve scheduling. And then there are system interdependencies. How does an EIU fault affect FADEC? How does an LGCIU fault affect FADEC?
      If you loose the FADEC (both channels) for a given engine, you've lost control of the engine. Either the engine will self-shut down or it will keep at a constant fuel metering valve setting, constant stator vanes position, constant bleed air doors setting, etc. t that point the only control you have is cut the fuel and shut it down.

      BUT, the plane can be designed to keep working with automatic thrust, automatic acceleration and deceleration schedules, etc. An engine failure can be made almost transparent for the pilot. Of course he will need to consider that his service ceiling and go-around climb gradient are lower, and that if he looses another engine he is in a glider.

      --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
      --- Defend what you say with arguments, not by imposing your credentials ---

      Comment


      • Originally posted by Gabriel View Post
        If you loose the FADEC (both channels) for a given engine, you've lost control of the engine. Either the engine will self-shut down or it will keep at a constant fuel metering valve setting, constant stator vanes position, constant bleed air doors setting, etc. t that point the only control you have is cut the fuel and shut it down.
        I recall the situation with Quantas Flt 32, where the data signal from the thrust levers to the FADEC was severed and the engine remained at its current thrust. I thought it was designed to go to flight idle or even shut down, but then again, that wasn't actually a FADEC failure. In any case, not ideal.

        BUT, the plane can be designed to keep working with automatic thrust, automatic acceleration and deceleration schedules, etc. An engine failure can be made almost transparent for the pilot. Of course he will need to consider that his service ceiling and go-around climb gradient are lower, and that if he looses another engine he is in a glider.
        Yes, but it sort of already is, since the thing has dual, redundant channels. I'm not aware of a case of dual channel FADEC failure. Perhaps a single channel is a MEL item and the second channel failed? I don't have any precedent fo that. Maybe you do...

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        • A pilot whose story became a Hollywood film knows the panic that faced crews on Boeing's doomed aircraft.



          "I can tell you first hand that the startle-factor is real, and it's huge. And it absolutely and it quickly interferes with one's ability to quickly analyse the crisis and take effective action."

          "Within seconds, these crews would have been fighting for their lives in the fight of their lives."

          "While everyone has a duty to keep passengers and crew safe, he said, 'first, we should design aircraft for them to crew that do not have inadvertent traps set for them'".

          Comment


          • Boeing sued by more than 400 pilots in class action over 737 MAX's 'unprecedented cover-up'


            More than 400 pilots join a class action against Boeing, seeking damages in the millions over what they allege were "known design flaws" in the latest edition of its top-selling jet, the 737 MAX.

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            • Originally posted by vaztr View Post
              Boeing sued by more than 400 pilots in class action over 737 MAX's 'unprecedented cover-up'


              https://www.abc.net.au/news/2019-06-...7-max/11238282
              i'm gonna go on the record and state that this suit will fail. i haven't read the actual complaint, but i'm guessing that no single airline has furloughed 400 pilots as a result of the max grounding.

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              • Originally posted by Gabriel View Post
                Ok so maybe it is time to define "complex" and how to measure complexity.
                If accurate, this article is suggesting there may be another failure mode that creates runaway stabilizer trim, this one related to a microprocessor failure:

                https://www.cnn.com/2019/06/26/polit...law/index.html

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                • Originally posted by flashcrash View Post
                  If accurate, this article is suggesting there may be another failure mode that creates runaway stabilizer trim, this one related to a microprocessor failure:

                  https://www.cnn.com/2019/06/26/polit...law/index.html
                  Yep, just read that. Guessing it has to do with error handling in the case of lost input. I guess the good news is that they are doing thorough non happy path testing.

                  Comment


                  • so, if anyone was looking for evidence of a corrupt corporate culture, here it is: "Boeing agrees with the FAA's decision and request, and is working on the required software..."

                    really? how mighty nice of you to "agree" with the certifying agency's decision. clearly, in the past, boeing didn't "agree," did things their own way, and killed 346 people.

                    and they continue to put profit over safety: "Boeing has proposed computer-based training which could be completed quickly and on an iPad." cuz ya know the airlines are gonna demand that boeing pay for REAL training since they promised no additional training costs....

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                    • Somewhat terse statement from FAA:

                      https://www.faa.gov/news/updates/?newsId=93206

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                      • Outsourcing...
                        Boeing has informed the FAA that certain 737NG and 737MAX leading edge slat tracks may have been improperly manufactured and may not meet all applicable regulatory requirements for strength and durability.

                        Following an investigation conducted by Boeing and the FAA Certificate Management Office (CMO), we have determined that up to 148 parts manufactured by a Boeing sub-tier supplier are affected. Boeing has identified groups of both 737NG and 737MAX airplane serial numbers on which these suspect parts may have been installed. 32 NG and 33 MAX are affected in the U.S. Affected worldwide fleet are 133 NG and 179 MAX aircraft.
                        There was an incident of an aircraft (can't recall if it was a 737) catching on fire on the ground as the result of a slat track issue. I think it resulted in a fuel tank breach. I'll have to find it...

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                        • Here it is: China Airlines Flt 120, indeed a 737NG:



                          Probably a failure unrelated to the current issue, but it illustrates how a seemingly innocuous issue involving a slat mechanism can have catastrophic consequences.

                          Comment


                          • Originally posted by TeeVee View Post
                            and they continue to put profit over safety: "Boeing has proposed computer-based training which could be completed quickly and on an iPad." cuz ya know the airlines are gonna demand that boeing pay for REAL training since they promised no additional training costs....
                            That is industry standard for differences training.

                            --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                            --- Defend what you say with arguments, not by imposing your credentials ---

                            Comment


                            • Originally posted by Gabriel View Post
                              That is industry standard for differences training.
                              Not quite, but I take your point.

                              Comment


                              • Originally posted by Gabriel View Post
                                That is industry standard for differences training.
                                really? that's not what 737 pilots are saying, especially about this particular "difference"

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