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Engineer Questions Saftey of A380 Cabin Pressurization System

Discussion in 'General Topics' started by tonyw, Oct 4, 2005.

  1. tonyw

    tonyw Well-Known Member

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  2. BrettInLJ

    BrettInLJ Well-Known Member

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  3. seagull

    seagull Well-Known Member

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    Common folks, think about this. First off, an MD11 could lose 2 cabin windows totally and maintain pressurization. This aircraft has twice the volume, more airflow potential and these outflows are the size of a window? This isn't a little learjet we're talking, it would take a long time to lose the cabin even if all four happened to fail at once. Of course, the odds of that would be somewhere smaller than 10^-20th.

    This guy may or may not have found some minor issue, but he doesn't know squat about airplanes. He's a computer geek.
     
  4. B767Driver

    B767Driver New Member

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    I agree with the engineer. On every airplane I've flown with an electronic pressurization system, the primary system has failed at least a couple of times per year. The backup system picks up the slack seamlessly. If the backup system fails...there is the third alternate...the manual control system. They all have separate power sources...and the manual system has a separate actuator.

    With this proposed design there does not appear to be a backup system at all. I suppose they could engineer the valves to failsafe closed. But this only corrects for pressurization problems. What happens if they want to ventilate the cabin for smoke & fumes? What happens when the primary (only) controller fails...no MEL relief to continue flying with a secondary controller.

    Limited info in the article...but it does seem like a limited design appliance.
     
  5. mpenguin1

    mpenguin1 Well-Known Member

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    Interesting subject, I was speaking with some Boeing Engineers about this subject yesterday, the Boeing engineers seem to think that this It may be a little blown out of proportion. But, it is one of those stories where we really don't know all the true factual details, so they do not want to speculate too much.

    One of the guys in our discussion said, "four microprossessors on four engines failing all at the same time...what are the odds?" I really don't know myself ( I am not an engineer) . But, it seems like this thing got so big so fast that the courts will see documentation on both sides, eventually. I look forward to following it & will pump the Boeing folks some more.

    When you start talking of backups to the backups, hell, with that line of thinking, we would still be flying "4" Engine aircraft across the ocean.
     
  6. B767Driver

    B767Driver New Member

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    I may have misread the story...now I cannot access the link. But I thought the issue was that there was only one controller and one actuator. I have a hard time believing that to be true, though.
     
  7. BrettInLJ

    BrettInLJ Well-Known Member

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    When you are dealing with software and microprocessors this can happen if they are all programmed with the same code and all encounter the right trigger of conditions at the right time to cause a failure (think Y2K bug). These conditions may be a combination of cycles or pressure combinations, that they could indeed all encounter. If I understand the allegations the engineer is making, he is saying that TTTech is modifying or changing the configuration of the microprocessors, yet they are being certified as a commercial off the shelf product.

    Software is never 100% bug free no matter how much testing is done. Software bugs have killed before, and they will again. If everything the engineer is saying is true, which is still a big "if", then as a former software engineer I would have to agree with him that there should be a redundancy of different processors. When it comes to software, I know to much about it to trust it without an independent backup.
     
  8. Derg

    Derg Major Domo Staff Member

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    They're all going to fall out of the SKY!

    (read: Good morning (well evening from us) from Koln, Germany -- fresh off the DB "ICE" from Berlin!)
     
  9. seagull

    seagull Well-Known Member

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    Four controllers, four actuators, four outflow valves, each the approx size of a cabin window.
     
  10. B767Driver

    B767Driver New Member

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    So what's this guy's problem?
     
  11. BrettInLJ

    BrettInLJ Well-Known Member

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    Actually in my scenario, the odds of all outflows failing due to the bug would be the same as one failing. If the new code or configuration does not go through certification testing because it is considered and off the shelf product, then the odds are much greater than 10^-20. However, I do not know much about pressurization systems yet so if what you say is true, that is that all valves could fail and open and there still be plenty of time to react, then the risk of any resulting death is low.
     

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