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Al Jazeera investigates - Broken dreams: The Boeing 787

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  • #16
    Originally posted by TeeVee View Post
    ...NEVER EVER...
    ...NEVER...
    ...NEVER...
    ...ALL...
    ...ALL...
    Lot's of absolutes there my friend.

    Guess what, going 500 MPH 6 miles up in the sky in a thin composite tube flown by humans (who have to guide it to a nice gentle, controlled crash where nothing breaks) ain't perfectly safe.

    And someone's gonna debate how thin you can make the skin, or the bolt that holds the engine on, but no one really knows, but gas is expensive, and reduced weight saves money so you can offer lower fairs on travelocity.com.

    All chemicals are safe? I dunnno, have you ever read the alarming stats on the risks of dihydrogen monoxide? It's dangerous stuff, and all joking aside, the death toll is 100% real. But then again, I'm against banning it.

    Just a friendly reminder that there's an elusive middle ground that you like to gloss over when you are in trial lawyer mode.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    • #17
      Originally posted by 3WE View Post

      And someone's gonna debate how thin you can make the skin, or the bolt that holds the engine on, but no one really knows, but gas is expensive, and reduced weight saves money so you can offer lower fairs on travelocity.com.:
      Well, somebody knows. They are called ENGINEERS and they have COMPUTERS that tell them material requirements for stress loads. Then they add the required margin on top of that and that is their MINIMUM requirement. If it needs to be lighter they have to find lighter materials that meet those same stress load requirements. Nobody can claim that Boeing isn't meeting these requirements. The issue they are raising lies in MANUFACTURING not engineering. Except for the battery issue which seems to present enough engineering unknowns that Airbus opted out of it altogether.

      Now perhaps someone, perhaps an ENGINEER, perhaps named GABRIEL, can tell us what kind of pressures might build up inside a sealed titanium box with a raging lithium ion furnace at work inside it, and for that matter how much of the heat of that inferno might transfer to the fixtures holding the box and the fuselage supporting that. What might happen over, say, 330 mins?

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      • #18
        Actually, this article answers a lot of questions:



        The battery fix should work in relieving pressure and preventing oxygen from initiating combustion but the enclosure has no redundancy to it as far as I can tell. A single failure will render it useless. it is not fault tolerant or fault passive. If a battery fire reoccurred and a valve or seal on the enclosure failed due to manufacturing defect or improper maintenance ("yeah, I found one just like it at Home Depot... valves are valves"), then we will have to land in 15 mins.

        Now what are the ETOPS requirements again? Who wants to buy an ETOPS15 787?

        Reading this article and seeing what steps have been taken, it also shows how many safety questions were not asked during the original certification process. In retrospect it seems pretty reckless to have allowed the plane into service. Point Al Jazeera.

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        • #19
          Ok, hold on here...

          In the article I posted above you find the following quote:

          Even when the electrolytes oxidize “they don’t release sufficient oxygen to materially contribute to combustion,” Sinnett says. A battery failure was induced in an enclosure in the test lab by exposing it to heat transmitted through the casing. “In no cases were we able to ignite electrolytes coming out of the cell,” he adds. The test team then drew oxygen back into the enclosure. “There was a small amount of combustion for 200 milliseconds and it went out again.”
          So, by isolating the battery from oxygen, as the enclosure is designed to do, combustion is prevented, while exposing it to oxygen, as would be the case if a pressure disk is burst, allows combustion to occur.

          Then I read this, also in Aviation Week:



          The FAA is allowing 21 flight cycles with the key safety feature of enclosure disabled.

          The“FAA arrived at a 21 flight cycle MMEL relief with the following logic: In a worst case scenario, the indicator fails on the first flight after the mandatory maintenance 14-cycle inspection has been completed,” the FAA tells Aviation Week. “After inspection, 13 flight cycles later, it is discovered the indicator has failed. If the Fault Isolation Manual process determines it is a faulty indicator, the 21 flight cycles Boeing requested for their MMEL relief falls within the 35 flight cycles Boeing has already tested.”
          If you read the article, you will see that the "35-flight cycles" are to test the capability of the battery to perform in unpressurized space at altitude. No consideration is mentioned here about the ability of the battery to achieve combustion now that the pressure disk is burst.

          ?????????

          No, this whole thing stinks of convenience.

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          • #20
            Originally posted by 3WE View Post
            Lot's of absolutes there my friend.

            Guess what, going 500 MPH 6 miles up in the sky in a thin composite tube flown by humans (who have to guide it to a nice gentle, controlled crash where nothing breaks) ain't perfectly safe.

            And someone's gonna debate how thin you can make the skin, or the bolt that holds the engine on, but no one really knows, but gas is expensive, and reduced weight saves money so you can offer lower fairs on travelocity.com.

            All chemicals are safe? I dunnno, have you ever read the alarming stats on the risks of dihydrogen monoxide? It's dangerous stuff, and all joking aside, the death toll is 100% real. But then again, I'm against banning it.

            Just a friendly reminder that there's an elusive middle ground that you like to gloss over when you are in trial lawyer mode.
            i wasn't in trial lawyer mode. that was sarcasm my friend. but you got my point.

            sure everyone wants cheap fares--and with the number of times i fly, i'm damn sure one of them. but i will not fly an airline or aircraft I alone feel or think is unsafe. my reasoning is not relevant cuz only i am involved.

            however, i the old adage "if it smells like shit..." comes to mind with this 787 nonsense. if it were only 1 mid-level ex employee grumbling about shit, i would pay it no heed. that is not the case.

            and yeah AJ made that piece far to melodramatic, but not quite shock journalism. there were no plane crashes or mention of such. lighining? yeah, stupid. but stupid sells. there was also a rather large amount of artistic shit that had no place in the piece--long shots of doorways, for example.

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            • #21
              - The box (enclosure) is 1/8" (about 3mm) thick stainless steel, not titanium. The venting duct is made of titanium.
              - The burst disk is designed to keep the battery compartment pressurized, not to prevent O2 to enter the enclosure.
              - In the event of a battery failure where the electrolyte is released, the rapidly expanding electrolyte will first raise the internal enclosure pressure (if there is a burst disk) until the burst disk fails. Then the max pressure that the enclosure needs to withstand is the pressure needed to burst the burst disk, and I bet my sandwich that said disk is thinner than the enclosure (or made from a weaker material).
              - Then, and even if the burst disk was burst before the battery failure, since gaseous electrolyte will be flowing overboard through the venting tube, no fresh air will be able to come in through the same duct. Hence no O2 and no fire.
              - I don't know why people is so concerned regarding whether there will be a fire or not inside the enclosure. My old stove had gas burners. My new one has electric hotplates, and you bet that it cooks the food even if there is no fire. Believe me, a ion-Li battery of this size can produce quite a bit of heat if shorted, even if there is no fire. So the key is that the enclosure must have enough thermal resistance to withstand the heat that would be released even with no fire. I prefer to think that Boeing made the calculations right.
              - If the enclosure is good enough to withstand all the energy stored in the battery, then time is not a factor. ETOPS 15 or ETOPS 1500 is the same.

              --- 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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              • #22
                It left too many loose ends to make any assumptions, disgruntled employees that make harsh comments on the product they make and without displaying their identity.
                The 787 has been plagued with poor management for a long time so I think they are more likely to controll the product more carefully than their previous models.
                "The real CEO of the 787 project is named Potemkin"

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