Announcement

Collapse
No announcement yet.

ANA 787 Emergency Landing in TAK - FAA grounds 787

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Originally posted by Alessandro View Post
    Mr Elon Musk explains what he thinks is the problem,
    http://www.flightglobal.com/news/art...unsafe-381627/
    Mike Sinnett, Boeing's 787 chief project engineer, explained the careful design philosophy employed for the 787's battery system, the first to serve as a starter for an auxiliary power unit and emergency power back-up in a commercial aircraft.

    "I design a cell to not fail and then assume it will and the ask the next 'what-if' questions," Sinnett said. "And then I design the batteries that if there is a failure of one cell it won't propagate to another. And then I assume that I am wrong and that it will propagate to antoher and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."
    And yet...

    --- 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


    • I keep seeing this type of statement re the 787 battey incident:

      Experts say the 787 relies more heavily than the A350 on electrical systems instead of traditional hydraulics to control brakes and other systems, and therefore needs more power back-up.
      Source: http://news.yahoo.com/airbus-says-pl...--finance.html

      It sounds like media reporters do not read the Boeing and NTSB press releases and otheer publically available information? The plane is powered during flight by several electrical generators powered by engines and the APU (not to mention the RAT) which provide the "more power"

      Comment


      • Does the 787 actually need this "backup" battery?

        The following suggestion is made to draw out the latent knowledge held within this forum and to get some debate going. I'm a professional Engineer although I have little knowledge of aircraft systems.
        Simplistically I ask what function does this battery provide that is not already covered by multiple redundancy (7 different generator feeds / circuits etc)?
        If the battery were not to be fitted it would eliminate the current symptom of the issue which simplistically meets the requirement of the AD.
        APU startup without external power would be compromised but is this function a WANT or a MUST?
        A work around of this type would buy time for the electrical issue to be further investigated and subsequently resolved.
        ...or maybe the battery is purely a symptom of uncontrolled surges and spikes in the power system which may in fact be exacerbated by removal of the battery?
        I suspect that there is a lot more to this issue than "spontaneous" thermal runaway of the battery. i.e. The battery is a symptom rather than the cause...in which case I can't see this being resolved quickly.

        Comment


        • Originally posted by snanceki View Post
          .......................Simplistically I ask what function does this battery provide that is not already covered by multiple redundancy (7 different generator feeds / circuits etc)?
          ..............................
          See post number 91.

          Comment


          • A timeline of the 787s problems, http://www.flightglobal.com/features/787-woes/
            "The real CEO of the 787 project is named Potemkin"

            Comment


            • Originally posted by snanceki View Post
              APU startup without external power would be compromised but is this function a WANT or a MUST?
              If you had a dual engine failure at 5000ft, like in the US Air Hudson ditching, believe me you will want an APU that can start without external power.

              --- 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 Highkeas View Post
                I keep seeing this type of statement re the 787 battey incident:

                Experts say the 787 relies more heavily than the A350 on electrical systems instead of traditional hydraulics to control brakes and other systems, and therefore needs more power back-up.
                Source: http://news.yahoo.com/airbus-says-pl...--finance.html

                It sounds like media reporters do not read the Boeing and NTSB press releases and otheer publically available information? The plane is powered during flight by several electrical generators powered by engines and the APU (not to mention the RAT) which provide the "more power"
                An APU that is able to provide "more power" is "more powerful", bigger and heavier, and needs "more power" to be started.

                --- 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


                • THere's an article in the Seattle Times quoting some Boeing engineers stating that the batteries are actually only the tip of the iceberg, whilst the base is the power panels:

                  Comment


                  • How much weight would be added to the 787 if traditional lead cadmium batteries were installed, in place of the lithium ion batteries now in place? How much would it cost?

                    I just can't understand why Boeing would go with the more risky lithium ion batteries-I mean, it's not like they didn't make the 787 light enough without them.

                    Comment


                    • Originally posted by UALdave View Post
                      How much weight would be added to the 787 if traditional lead cadmium batteries were installed, in place of the lithium ion batteries now in place? How much would it cost?

                      I just can't understand why Boeing would go with the more risky lithium ion batteries-I mean, it's not like they didn't make the 787 light enough without them.
                      Its also a matter of size, since other batteries with the same amount of juice will be larger.
                      Another interesting claim is that the current batteries on the 787 only can be used up to
                      85% otherwise the get locked. I heard the term "usable fuel" but not "usable electricity"?
                      "The real CEO of the 787 project is named Potemkin"

                      Comment


                      • Originally posted by Alessandro View Post
                        Its also a matter of size, since other batteries with the same amount of juice will be larger.
                        Another interesting claim is that the current batteries on the 787 only can be used up to
                        85% otherwise the get locked. I heard the term "usable fuel" but not "usable electricity"?
                        http://seattletimes.com/html/busines...mid=obinsource
                        Not that uncommon - it (ironically) with some battery types improves longevity.

                        The battery in the Toyota Prius is only ever allowed to charge to 80% and discharge no lower than 40% - effectively you have a battery pack you are only using 40% of its total capacity out of.

                        See here for more: http://www.hybridinterfaces.ca/stockNIMH.html


                        Same with Lead acid chemistry - many people believe that because they have a deep cycle battery in their RV/House/ Second battery in the 4x4 that they can regularly cane all the energy out of it. Cycle life in all lead acid chemistry is massively improved the lower the depth of discharge.



                        The only battery that seems to be the exception to this is NiFe chemistry.

                        Comment


                        • Looks like Boeing is flight testing one of the frame today from FTW to PNE.



                          Nevermind. Its just a relocation flight with special permission from the FAA.
                          Last edited by saupatel; 2013-02-07, 18:33.

                          Comment


                          • Today's NTSB press release

                            Comment


                            • lithium ion battery tech is crap. i've bought two "high tech" high dollar kits for my buddy's motorcycle and both have failed very early in their lifespans. both appeared to have shorted internally and caused major deformation of the outer case.

                              on several of the motorcycle forums i participate in, i've read countless other instances of arcing, shorting, deformation etc etc, and ALL with lithium ion technology. it may work ok for small tech but as they get bigger, they appear to be worthless. shit! even in laptops they caused fires!

                              WTF was boeing thinking?

                              Comment


                              • Originally posted by TeeVee View Post
                                lithium ion battery tech is crap.

                                WTF was boeing thinking?
                                I don't know, but probably something along the lines of what Toyota, Honda and Ford were thinking for their hybrid cars. I haven't heard of many cases of batery fires in hybrid and electric cars. In fact, I haven't heard of a single one.

                                --- 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

                                Working...
                                X