NTSB B787 Battery Hearing reports

Discussion in 'General Discussion | Travel' started by jbcarioca, Apr 24, 2013.  |  Print Topic

  1. jbcarioca
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    jbcarioca Gold Member

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    There are several press reports, so I will not make comments about those, but emphasize points I thought would be of special interest to us.

    First, the headlines:
    Boeing, Thales, GS Yuasa and the FAA were the witnesses.

    There was a board of NTSB investigators asking questions which included three people with the statistical analysis backgrounds and accident investigation histories that made them hard to "snow".

    Representatives of JCAB and EASA were also present and asked questions also.

    Major points:
    Mike Sinnett of Boeing insisted that only a catastrophic event (i.e. destruction of the airframe) would be thermal runaway. GS Yuasa, Thales, JCAB and EASA indicated their definitions fit the industry standard. As Takahiro Shizuki of GS Yuasa said "thermal runaway is the uncontrolled heating of a cell".

    The FAA did not ever have any direct contact with either Thales or GS Yuasa during the certification effort. The entire design, development, test plan, testing, validation and certification of the battery and the electrical components were certified by Boeing employees under DER (Designated Engineering representative) authority in the early years of the program, under ODA (Organizational Design Authority) that Boeing had later in the program the FAA does not even select or supervise the AR (Authorized Representatives) because Boeing selects, trains and supervises them, whereupon they then execute FAA authority. (Note: you could not invent this. The FAA developed it in the mid 1990's.

    Boeing now has approximately 950 AR's. The FAA has 23 employees who were full time on the B787 program, and about another 22 FTE composed of part time experts. When this began the FAA had no engineer qualified in li-ion battery technology. It might now have mattered since Boeing had effective self-certification anyway.

    Of the ~100 batteries returned to GS Yuasa by Boeing about 2/3 were due to over discharge, mostly by Boeing's own mechanics who left the main ship power on too long, thus destroying the batteries (a latch mechanism physically melts and disables the battery when it is over discharged). Most of the remaining 1/3 were disconnected while charging, again by Boeing, mostly. Some carriers are certified to do maintenance of the batteries themselves.

    The BOS incident was not considered fire by Boeing because the flame was "only about the size of a cigarette lighter flame", so not a fire. Boeing thinks a fire must be more robust than that.

    The BOS incident had multiple shorts in cell #6 which encountered thermal runaway and then propagated to other cells. When NTSB questions were made to that the Thales people objected because the root cause had not been identified. NTSB chairman stated that as a factual matter the events were known, but the causality was not.

    Boeing and FAA testified that the system worked and there had been no risk to airplane nor people. Both thought the existing "special conditions" were fine, and that these two incidents should be treated as inservice problems.

    There were two battery redesigns following the first one.

    Battery #1 was the one that Securaplane was testing with the BMU disabled which exploded and burned down the building in which the test was happening. Additional protection was built into the cells.

    Battery #2 was the one that encountered electrolyte leaking during testing at a Boeing facility. The battery case was redesigned to seal the case.

    Battery #3 was the one involved in the JAL and ANA cases.

    Now Battery #4 is the one approved last week.

    GS Yuasa says they have built 14,000 analogous cells since 1991 and had no thermal runaway or other incidents with any of them.

    Thales had no previous Li-ion experience, so depended on GS Yuasa.

    Boeing, Thales, GS Yuasa and Securaplane were all participants in developing the industry standard DO-311. That standard, which Mike Sinnett had weeks earlier been quoted as saying there was no industry standard to follow, was developed with a Boeing employee as Chairman of the committee. Boeing and all parties had the full standard in 2008, three years before certification of the airplane.

    I have about ten pages of notes on the two day sessions. The full transcripts and supporting materials are at the NTSB site now.

    If anyone wants more detail from my notes please ask and I'll try to add.

    Finally, a distinct note. The FAA has used Designees to perform regulatory execution functions for at least 50 years, and the CAB did so too. Among those were Designated Pilot Examiners (During my flying career I earned 14 different certificates/ratings. I had two FAA employees conduct tests, all the rest were designees). The difference today is that the FAA no longer supervises directly the DER's and other designees, but delegates the authority to the regulated manufacturer to select the people who will then exercise FAA authorities. Further, these people can and do, says Boeing, help design the product that they then test and certify under these authorities. That is a huge change from the former designees, who were directly supervised by FAA employees.

    The FAA entire Aircraft Certification Service has 1275 employees today, but is losing some. That includes people to supervise six major transport category aircraft programs as well as ongoing in-service matters and minor changes. remember Boeing has 950 AR's by itself.

    Do we all feel more secure now?
     
  2. HaveMilesWillTravel
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    HaveMilesWillTravel Gold Member

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    Nope.

    So if Boeing thinks BOS wasn't a fire, what would have happened if the FIRE fighters hadn't extinguished the non-fire? Would there now be a molten pile of plastic glued to the tarmac next to the terminal?
     
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  3. LETTERBOY
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    LETTERBOY Gold Member

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    I feel about the same regarding the 787 as I did before. If the FAA says it's OK to fly, I'd be willing to get on one, though I wouldn't go out of my way to do so. I'm not too fond of Boeing, but that doesn't have much to do with whether or not the 787 is safe.
     
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  4. jbcarioca
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    jbcarioca Gold Member

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    It is actually not so cut and dried as Boeing does not think something went wrong but they they are, it seems to me, obsessed with avoiding any admissions that might diminish their legal position. Therefore, they defined (Mr. Sinnett did anyway) thermal runaway as something that would cause destruction of the aircraft, i.e. a "catastrophic' event. He elaborated that their position was that anything short of that would be dealt with by the various levels of systems protection, so he stated that the systems worked as designed. Other Boeing people echoed that position. From their perspective I do understand the position, although I think they might be better off to discuss the component failure rather than insisting that only airplane level should be their measure of merit. We do need to allow them to parse their words, irritating as that is. If one accepts their premise, the systems worked as designed. The FAA's position is that they cannot know since the protective systems were, mostly, designed for in-flight use and the BOS incident was on the ground. According to Boeing the ANA incident did not involve fire, and no smoke entered the aircraft, only " reports of odors were received".

    I am quite confident that the battery problems for the B787 are over, at least for the APU and main ships batteries. The other three li-ion batteries installed in the B787 have been mostly not discussed. However, the A380 has had zero problems with li-ions.

    A personal suspicion is that they actual cause of these incidents was repeated over-discharge of the batteries, but below the level that would trigger the 'latch'. Mike Sinnett did state that the current draw of the B787 systems was about 10 Amps on the ground, vastly higher than in any other Boeing or Airbus. thus mechanics who lack specific B787 training leave the main power on for "too long". That was the cause of about 2/3 of the battery failures, he said. It is quite easy to imagine that such things happen elsewhere without quite triggering the 'latch'. The high number of batteries replaced by ANA and JAL suggest that might be the case, although nobody outright said that. if so, this repetitive near over-discharge could be the real culprit by allowing copper migration in the electrolyte and exposing risk of internal shorts. Multiple internal shorts DID happen to cell #6.
    This was not discussed in detail as the revelation happened parenthetically at the very end of yesterdays session.

    Another opinion is that the participants, almost all of them, were earnestly trying to determine exactly why this happened. However, I do suspect Boing understands very well that the design that places a 10 amp load on the main battery during ground servicing is placing an undue burden on that battery. I will be pleased if they redesign that to eliminate the problem rather than depending on ground handlers (e.g. mechanics) to remember the type differences when there are, say, 1000 of these in service. I do not expect them to ever postulate that repeated ground over discharge abuse below the latching limits might be the actual cause of the internal shorts. They don't need to admit that if they alter the design to eliminate the problem. Maybe they already have. replacing 100 batteries in a total constructed fleet of 100 (Boeing has built ~100 B787's so far) does impose a cost at $16,000 each.

    I'd fly on the airplane now, but I do expect to see more problems with poor electrical system integration. Partly that may stem from the fact that the B787 was originally designed to have ni-cad batteries and switched to li-ion a couple years after the design began. Did they alter all the critical features to consider that change? I do not think any future failures will be life-threatening, but I know that is a statistical possibility.
     
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  5. milchap
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    milchap Gold Member

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    I will wait until the aircraft get more hours before I get on board.
    I still am not comfortable and I will wait until Air Canada accepts delivery in 2014.
    And thanks jbc for the report.
     

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