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Japanese Probe Finds Miswiring of Boeing 787 Battery 201

Posted by samzenpus
from the who's-to-blame dept.
NeverVotedBush writes in with the latest installment of the Dreamliner: Boeing 787 saga. "A probe into the overheating of a lithium ion battery in an All Nippon Airways Boeing 787 that made an emergency landing found it was improperly wired, Japan's Transport Ministry said Wednesday. The Transport Safety Board said in a report that the battery for the aircraft's auxiliary power unit was incorrectly connected to the main battery that overheated, although a protective valve would have prevented power from the auxiliary unit from causing damage. Flickering of the plane's tail and wing lights after it landed and the fact the main battery was switched off led the investigators to conclude there was an abnormal current traveling from the auxiliary power unit due to miswiring."
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Japanese Probe Finds Miswiring of Boeing 787 Battery

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  • by DavidRawling (864446) <hulk_.yahoo@com> on Wednesday February 20, 2013 @08:54PM (#42961301)
    Who will it be? Maintenance? Boeing?
    • by the eric conspiracy (20178) on Wednesday February 20, 2013 @09:03PM (#42961371)

      Outsourcing contractor.

    • by Anonymous Coward on Wednesday February 20, 2013 @09:13PM (#42961445)

      Really? I am actually quite impressed. The degree of investigation over lighting failures and back up safety systems and all that is pretty awesome. Putting aside my condemnation of corporations like Boeing, this mess isn't damning, but rather assuring. Any finger pointing should be met with a reminder that the plane landed just fine. Granted, I'd be annoyed if my flight was grounded for this nonsense but degree of blame should reflect the problem caused.

    • by bobbied (2522392) on Wednesday February 20, 2013 @09:27PM (#42961549)

      Who will it be? Maintenance? Boeing?

      All of the above!

      I'm skeptical of this story. They are basically saying that somehow the wiring got messed up in such a way that everything still worked, but the battery was improperly charged/discharged by the APU. The evidence they have is some lights that flickered. This seems fishy to me.

      If something is miswired, then it's going to be possible to PROVE that as fact. Even if the unit was cut from the aircraft, it would be possible to physically inspect and verify what wire went where. Flickering lights are NOT PROOF of anything being incorrectly wired.

      If the drawings don't match the design, you can PROVE that by inspecting the drawings. If the aircraft doesn't match the drawings you can PROVE that by inspecting the aircraft. We have NO proof here.

      I'm guessing that somebody in Japan wants to get these aircraft back into the air, bad enough to come up with some story with flimsy evidence and managed to get Japan's version of the NTSB to agree.

      • Add to that that there were other, less severe but similar problems with the battery on other planes.

        Also, I'd say (but nobody listens to me anyway) that if the battery can be misswired like that, it's a design flaw and Boeing should issue a correction. Of course, there is a lot of needed research before stablishing that the battery in fact has this problem, but that'd be the proper action.

      • by icebike (68054) on Wednesday February 20, 2013 @09:44PM (#42961657)

        I'm skeptical of this story. They are basically saying that somehow the wiring got messed up in such a way that everything still worked, but the battery was improperly charged/discharged by the APU. The evidence they have is some lights that flickered. This seems fishy to me.

        I tend to agree. The summary and TFA are so confusing, its hard to figure where exactly the miss-wiring was. Was it in the APU, or the APU's seperate battery, or the Main Battery, or what? They simply say the APU Battery was "incorrectly connected". Does that mean it was never intended to be connected to the main battery, or was reverse wired, or shorted or operates as a different voltages, or what?

        So far Boeing is mum on this particular report.
        Instead they are proceeding with insulation between battery cells [nytimes.com] and cooling.

        Boeing’s plan would be to redesign the batteries to place insulation inside and around each of the eight cells to minimize the risk that a short circuit or fire in one of thecells could spread to the others, as investigators have said occurred on the battery that caught fire in Boston on Jan. 7. Boeing might also adjust how tightly the batteries are packed.

        So no clue what caused it but if we insulate the battery a little better maybe we can contain it? Seems almost as fishy as the article mentioned above.

        • by plover (150551) on Thursday February 21, 2013 @01:51AM (#42963273) Homepage Journal

          They learned at least two things from this incident, not one. The first lesson is that it was "miswired" (agreed, a fishy statement), but it means they can test some wiring or insulation in existing and future planes to make people think they're doing enough to get the planes back in the air. Second, and more importantly, they learned that the batteries can burn as a group, and that they need to minimize the damage a battery fire can cause by better restricting the ability of the fire to spread. So the next time this happens, the plane won't be at as much risk.

        • by aethelrick (926305) on Thursday February 21, 2013 @05:16AM (#42964555)

          a wiring problem could be as simple as using an incorrect thermistor on a Li-ion pack or not wiring a thermistor in at all. These are often used to alter charge/discharge rates in response to the battery pack temperature. A battery will still work in every other respect, except it won't respond accordingly in response to overheating. This is a fairly simple example of what could go wrong to cause a fire that would not stop the battery from working (until it failed by going on fire). The trouble with Li-ion packs is that if this happens (and it does) then the fire can very easily spread to the surrounding cells. I can see how this could cause short voltage spikes that would overcome resistance in a line to "flicker" a light.

          I'd just like to add, I may be totally wrong, but I thought I'd weigh in for the fair minded rather than the conspiracy theorists on this one. Also, before anyone assumes I'm a Boeing employee, I'm not. I'm just a bloke who works with Li-ion batteries and who has seen faults similar to this in the past.

      • by anubi (640541) on Wednesday February 20, 2013 @10:10PM (#42961831) Journal
        When I read of it, I felt more vindicated than surprised.

        During my tenure in aerospace, I had witnessed more and more of a disregard for detail work. What used to be a good thing called "attention to detail" started being regarded negatively as "being a perfectionist".

        The devil is in the details. Thousands of things work perfectly. One does not. This is the inevitable result of overlooking just one detail.
        • by router (28432) <a.r@NOsPam.gmail.com> on Wednesday February 20, 2013 @11:41PM (#42962471) Homepage Journal

          I agree.

          It shouldn't have been possible to "miswire" an aerospace battery, the connectors should have been coded, the wires, and the inspectors should have seen and tested this. Battery failure is still a process failure. Unfortunately, process failures are the most systemic failures possible. Lets hope I'm wrong....

          andy

          • by AmiMoJo (196126) * <mojoNO@SPAMworld3.net> on Thursday February 21, 2013 @08:42AM (#42965541) Homepage

            It wasn't the battery itself that was miswired, it was the backup battery. It sounds like they have a second battery for when the first is unavailable, e.g. during fast charging. Lithium batteries get very upset if you try to charge them too quickly, or overcharge them or charge them while drawing significant current. Furthermore if the backup battery is not isolated correctly from the main battery the charging circuit may not be able to determine the main battery's state correctly and end up overcharging it.

            Wiring to bother batteries is probably fine, the fault being with how they are connected to the rest of the aircraft.

          • by bobbied (2522392) on Thursday February 21, 2013 @10:45AM (#42966705)

            I agree.

            It shouldn't have been possible to "miswire" an aerospace battery, the connectors should have been coded, the wires, and the inspectors should have seen and tested this. Battery failure is still a process failure. Unfortunately, process failures are the most systemic failures possible. Lets hope I'm wrong....

            andy

            One must think about how aircraft are actually assembled. In most cases, wire bundles are installed without the terminating connectors installed on at least one end. This is because the connectors are too bulky to easily pull bundles though the small spaces required and it is difficult to know the exact length necessary to provide the proper clamping and clearances. It is simpler and cheaper to just install the wires and then cut them to length and install the connectors.

            Manufacturing processes for aircraft usually include a comprehensive double check of wiring harness installation. This includes manual and automated testing using machines the connect to the huge number of connectors in a wired aircraft, followed by extensive functional testing of just about everything. Errors are not uncommon, but they are generally caught and corrected long before the aircraft gets signed off as airworthy.

            Usually, manufacturing designs for aircraft include specific keying for connectors which might be miswired. This means that it would be impossible for an avionics mechanic replacing a battery to connect up something incorrectly, unless they altered the keying on the connectors or did something really stupid like re-routing an existing wiring harness to "make it reach". Both activities would be physically obvious.

            Beyond routine maintenance, you have ongoing modification processes, where wiring can get changed due to design changes. This process is very strictly controlled and involves a verification process that should have independent review of all the work done. If someone miswired the aircraft, and the review missed it, then ALL three entities are going to be at fault. The guy who re-wired it, the guy who signed it off as complete and the manufacturer who designed the verification test. Assuming everybody was following procedure and nobody is guilty of not doing their job.

            Again, this whole "it was wired incorrectly" idea sounds fishy to me given the "blinking lights" as evidence. Either the plane was wired wrong or it wasn't, and you can grab the design drawings and verify the wiring pretty quick. Now if they are saying there is a *design* issue, that too should be something that can be clearly explained by looking at the drawings. Reports of blinking lights might be an indicator of where to look, but it is not proof we found the problem.

    • by PolygamousRanchKid (1290638) on Wednesday February 20, 2013 @10:09PM (#42961825)

      Boeing should have called the Call Center Help Line. The first question they always ask, is, "Is the device plugged in correctly?"

      I find it mildly amusing that the Airbus A-800 also had problems with the wiring. They blamed that on a mismatch in CATIA system between French and German engineers.

      It's amazing, all those high-tech doo-hickies, whatchits and gadgets in the plane. . . and in the end a wiring problem causes the system to fail. Maybe in the future, they can just all use one bus, and get rid of the wiring.

    • by Runaway1956 (1322357) on Wednesday February 20, 2013 @10:52PM (#42962123) Homepage Journal

      It wasn't me! I swear it wasn't me! I've never worked on an aircraft in my life!

      Sux2bthatguy!!

      (Note that Runaway is color vision impaired, and has in fact wired things wrong from time to time.)

  • User error (Score:5, Interesting)

    by girlintraining (1395911) on Wednesday February 20, 2013 @09:01PM (#42961361)

    So basically, the user reached back behind the power supply while fiddling and bumped the 110/220V switch, and it caught fire. Naturally, they didn't say anything to the tech after setting the switch back besides, "It just caught fire! All by itself!"

    The user in this case is a giant airline company, and tech support would be Boeing. The FAA, of course, is the QA manager, who reviewed the call, and after reading the ticket closure notes, facepalmed, leaned back into his chair, and took a deep draft of coffee.

    • by Cassini2 (956052) on Wednesday February 20, 2013 @09:11PM (#42961431)

      Many power supplies are designed to autoswitch between 110V and 220V for just this reason. Cheap power supplies aren't.

      I knew one customer that said: "We didn't know that it was a 220V machine when we connected it to 600V!" That bang was audible.

      • Re:User error (Score:5, Interesting)

        by girlintraining (1395911) on Wednesday February 20, 2013 @09:16PM (#42961461)

        No no, I know. I was just reframing the "black and nebulous art" of airplane maintenance into something easier to digest for slashdotters. It was either that, or a car analogy, and turning a plane into a car just felt wrong. :) The truth is a bit more complicated; But it still boils down to operator error and not a design flaw. Of course, a design that allows someone to plug in one component backwards and have the entire device go up in flames is not a good one, but it's not flawed in the strict sense of the word. It's disappointing that my $500 laptop has a feature that prevents the battery from being plugged in backwards, but a multi-million dollar state of the art aircraft does not.

        • by drinkypoo (153816) <martin.espinoza@gmail.com> on Wednesday February 20, 2013 @10:22PM (#42961919) Homepage Journal

          You can't use a car analogy because the average slashdotter would cause the same kind of problem if they worked on their car. Auto shops are always seeing cars come in after they tell the customer about a problem with something fixed totally wrong, parts put on upside down and crap like that. Most people know jack diddly about cars. This, frankly, is a positive thing. I look forward to when they're all EVs and we can know even less about cars to keep them maintained.

          In any case, this is basically an ideal demonstration of Murphy's law, not the popular conception thereof, but the actual meaning and history...

        • by garyebickford (222422) <gar37bic@NospaM.gmail.com> on Wednesday February 20, 2013 @11:20PM (#42962325)

          Actually from my admittedly limited experience, FAA and airplane mfgrs are downright obsessive about making connections idiot proof and failsafe. It's pretty difficult to find places in an airplane where it's possible to plug the wrong things together or backwards. FAA has been dealing with Murphy for a very long time. In this case, if that's what happened, then it's one that slipped through the design and development process. FAA will mark this as a design failure and require Boeing to make it impossible to connect wrongly.

          One thing I've learned from reading NTSB and FAA reports after aviation accidents (they usually come out about a year after the accident) - there is ALWAYS someone who gets pinned to the wall. There's always someone, sometimes multiple someones, who gets blamed. And then corrective actions are set out for all concerned.

          • Re:User error (Score:4, Informative)

            by number11 (129686) on Thursday February 21, 2013 @12:17AM (#42962701)

            Actually from my admittedly limited experience, FAA and airplane mfgrs are downright obsessive about making connections idiot proof and failsafe. It's pretty difficult to find places in an airplane where it's possible to plug the wrong things together or backwards. FAA has been dealing with Murphy for a very long time. In this case, if that's what happened, then it's one that slipped through the design and development process. FAA will mark this as a design failure and require Boeing to make it impossible to connect wrongly.

            Looking at that Japanese powerpoint [mlit.go.jp], it looks like that may be exactly what happened. The battery cells are rectangular with a stud on each side of the top. Not even any prominent markings to indicate polarity, though the two studs seem to be mounted with different colored rivets. You'd think they'd at least have different diameter studs for the positive and negative, and jumpers with holes to match.

      • by peragrin (659227) on Wednesday February 20, 2013 @09:26PM (#42961537)

        actually at work we are dealing with that exact issue.customer returned an item that "stopped" working. After painfully trying to figure it out, we traced it to the power secondary power supply that converts 120 to 24v for the control systems. We replaced the PS tested the unit.

        The customer had it for less than 20 minutes when they called up and said it wasn't working again. A quick check and the new power supply was toast.

        They have a short in the box that supplies power to the unit in their shop dropping 240v into the machine at random.

        • by Obfuscant (592200) on Wednesday February 20, 2013 @09:37PM (#42961605)

          They have a short in the box that supplies power to the unit in their shop dropping 240v into the machine at random.

          Most modern, well designed power supplies can handle anything from 95V through 250V because that is what they could expect on their input depending on where in the world they are used.

          That's because they are switching power supplies, and instead of using a simple transformer to create the right internal voltage that is then rectified and provided to the powered equipment, they switch the incoming current to maintain the right voltage on the output.

          Now, I'd like to know where this "120/240V" stuff regarding the Dreamliner is coming from. TFA says nothing more than the summary about what was miswired. I'd suspect it wasn't a voltage issue when they say "a simple valve" would fix it (valve? Are they really using ancient tube-based circuits?). I'd suspect the problem is a current path that applies APU power to the batteries when it should not be. But, lacking any real description, it's a guess.

          • by colfer (619105) on Wednesday February 20, 2013 @10:51PM (#42962107)

            It was an analogy, bot really what is on the airplane.

          • by Nefarious Wheel (628136) on Thursday February 21, 2013 @12:36AM (#42962839) Journal

            Back somewhere in the late 60's-early 70's, there was a computer that came in for repair in the company I worked for - it was an SDS 930 (lovely old discrete-transistor machine). Someone had plugged a "MagPack" (an early cartridge tape drive) into the wrong slot on the bus, and the connector that was supposed to go there, into the MagPack's bus. The connectors were the same, but the circuits weren't. The circuit plugged into the MagPack's slot got a good healthy dose of one phase of a 440v power supply into a circuit that was expecting 0.5VDC. You could tell the logic state of the machine at that moment by following the carbon trails. Flipps were permanently flipped, flopps were permanently flopped. It looked like lightning had struck the frame.

            Connector standards, even for simple antiques like RS-232 were a revelation, and were a service to us all. Gotta remember that engineering practices didn't just appear, they evolved. I respect connectors, especially after diving into their construction in a bit of detail. Properly designed, any good standard wiring loom connector will give you very little grief.

            • by fluffy99 (870997) on Thursday February 21, 2013 @03:04AM (#42963807)

              You gotta love Dell who decided to make their PC power supplies a proprietary pinout but use the standard ATX power supply connector. Many unsuspecting folks tried to replace either the power supply of the motherboard, only to smoke the motherboard because the pinout was non-standard.

              • by AaronW (33736) on Thursday February 21, 2013 @03:43AM (#42964005) Homepage

                That reminds me of when I was working with an early revision of a new PCIe board. I double checked the auxiliary power connectors and found that they had used the wrong 8-pin connector. Instead of a PCIe power connector they used the motherboard power connector. The 8-pin PCIe power connector and 8-pin motherboard connectors are almost identical except the power and ground is swapped between the two and they're keyed slightly differently.It seems rather stupid to me. As far as I'm concerned they should have designed it such that the connectors and pinouts were the same.

  • by Grayhand (2610049) on Wednesday February 20, 2013 @09:23PM (#42961519)
    It's the damned metric +/- that causes all the confusion.
  • A protective valve? (Score:3, Informative)

    by dgharmon (2564621) on Wednesday February 20, 2013 @09:29PM (#42961557) Homepage
    "the battery for the aircraft's auxiliary power unit was incorrectly connected to the main battery that overheated, although a protective valve would have prevented power from the auxiliary unit from causing damage"

    What is a power diode [slashdot.org]
  • by Charliemopps (1157495) on Wednesday February 20, 2013 @10:00PM (#42961777)

    When you say "Japanese Probe" I had an entirely different idea in my head regarding what this story was about.

  • by Camel Pilot (78781) on Wednesday February 20, 2013 @10:55PM (#42962135) Homepage Journal

    For the Prius accelerator screwup....

  • by r00t (33219) on Thursday February 21, 2013 @02:27AM (#42963545) Journal

    You need a blow-out panel.

    The M1A2 Abrams tank has one for the shells. If they start to burn, the blow-out panel pops off and the whole mess exits the tank.

    Factories that make vinyl have them. When the concoction goes boom, blow-out panels prevent total destruction of the building. Workers may even survive.

    Meth labs don't have them. :-)

    A reasonable design would have several battery compartments, each with a separate blow-out panel. These should be located so that debris will not enter the engines or get run over by the landing gear. The rear underside seems like a good location.

    • by mjwx (966435) on Thursday February 21, 2013 @05:19AM (#42964589)

      Meth labs don't have them. :-)

      Ahem,

      Why do you assume just because I make meth, my lab is not set up to conform to AS2343 standards.

      For shame sir, for shame.

    • by Michael Woodhams (112247) on Thursday February 21, 2013 @06:50AM (#42964983) Journal

      Remember that an airliner is a pressure vessel. The maximum pressure differential is on the order of 60 kPa, which is about the pressure of a water column 6m deep. So you want a panel which will absolutely not ever blow out at 60 kPa pressure, but will reliably blow out at (60 kPa + excess pressure caused by fire.) Given that the battery is not in a gas-tight compartment, I can't imagine that excess is very large, even for a significant fire. And all this is without even considering the fact that 60 kPa is the maximum pressure differential, but during significant periods of the flight the difference will be less.

      I believe that blow-out panels are already used in the cabin floor so that should one (but not the other) of the hold and cabin suddenly depressurize, the floor will not fail. Such a failure of the floor was part of the chain of causation that caused a near crash [wikipedia.org] and a crash [wikipedia.org] in the DC-10. Wikipedia refers to 'vents' without specifying the type, but I remember reading elsewhere they were blow-out panels. (Although present, they proved inadequate, and improving them was part of the engineering fix made in response to these incidents.)

  • by KH (28388) on Thursday February 21, 2013 @10:12AM (#42966327)

    I see that the discussion here is based on a sketchy summary from the originally Japanese press conference. More coherent information is available if you could read Japanese but I know it's too much to ask for...

    Here is the latest update of the on-going investigation from the JTSB issued 20 Feb, 2013; this mentions the mis-wiring:

    http://www.mlit.go.jp/jtsb/flash/JA804A_130116-130220.pdf [mlit.go.jp]

    More in-depth information is given at

    http://www.aviationwire.jp/archives/16032 [aviationwire.jp]

    According to this article, the mis-wiring was in the original specs/design, and the design had been corrected. The aircraft in question was manufactured in accordance to the earlier specs but no modification was made to comply with the new ones. One can infer that the bug was considered insignificant to compromise the safety of the aircraft. The JTSB currently does not think this mis-wiring was the cause of the battery incident although they will keep looking into it as a potential cause of anomalous voltage readings.

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