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Dreamliner 787 crisis: NTSB clears an early suspect

This could be read as progress. It can also be read as confirmation that nailing the cause of at least one of two 787 battery related incidents that lead to Dreamliners being grounded is proving elusive, which isn’t good news.

A Bloomberg sourced report has cleared one of the early suspects, the battery charger, of being at fault in the fire that broke out in a Japan Airlines 787 Dreamliner at Boston’s Logan airport on 7 January.

This could be read as progress. It can also be read as confirmation that nailing the cause of at least one of two 787 battery related incidents that lead to Dreamliners being grounded is proving elusive, which isn’t good news.

It also keeps in the media spotlight concerns about how the FAA came to certify the use of heavy duty high output lithium ion batteries in the 787s in the face of significant concerns expressed by engineers with a working knowledge of the risks and issues associated with them.

An NTSB-led team also examined circuit boards used to monitor the battery in the in-flight incident in Japan, the board said. The circuit boards were damaged in the incident, “which limited the information that could be obtained from tests,” the board said. ”

The board said it had sent two additional investigators to Seattle, where it was working with the Federal Aviation Administration to review work at Boeing. One investigator will work with a group reviewing Boeing’s efforts to solve the problems, and the other will work on how the lithium-ion batteries were approved by the FAA.

The RTCA, a group that advises the FAA on some technical issues, in 2008 recommended tougher testing standards for lithium-ion batteries on aircraft to ensure they wouldn’t burn or explode even if control circuitry failed, The Wall Street Journal reported Sunday night. The FAA decided such testing wasn’t necessary, and it’s not clear whether it would have prevented the two 787 incidents, the Journal reported.

Here, the issues are more parochial. What will Qantas do? Does it need to do anything? Or,  is the delivery of Dreamliners anywhere near to being as immediately important as sorting out individual AOCs for Qantas domestic and international, or persuading the public that flying Emirates is really flying Qantas?

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  • 1
    keesje
    Posted January 28, 2013 at 7:37 pm | Permalink

    The WSJ report IMO shows the awareness of the risks associated with these batteries was there.

    http://online.wsj.com/article/SB10001424127887323644904578268280356405680.html

  • 2
    patrick kilby
    Posted January 28, 2013 at 8:29 pm | Permalink

    I note in another report the Japnese have ‘cleared’ the battery design but does that include the cooling systems of the battery as well, or are we all blame shifting; and Ben a QF flight to Gatwick when I want to go to Brighton is a great idea regardless of who owns and operates the plane, 20mins in a train versus 2 hours in bus.

    Flexibility and a wide range of choices is the name of the game; put I did not know this was coming a few months back when I booked the flight, and now the ticker re-issue is just too expensive – bummer!!!.

  • 3
    James Brown
    Posted January 28, 2013 at 10:18 pm | Permalink

    The technical details available are sparse, and the discussions seem not to reflect established knowledge or practice.

    The first issue is that batteries are a collection of cells. The Dreamliner batteries include eight cells each of 3.7 volt connected to produce a nominal 28 Volt battery. There are also many different designs of of Lithium rechargeable cells. Each individual cell of a lithium battery must be protected against over-discharge, which causes rapid loss of capacity, and overcharge which can cause a cell to overheat and catch on fire.

    The key issue is manufacturing defects, these can cause cell shorts which will cause rapid overheating and venting of flammable electrolyte. Once ignited there is no method of suppressing such a fire, it will burn even in a vacuum.

    All of these issues were recognised in the FAA additional safety requirements. Management of lithium cells and batteries is well established technology, it is included even in low cost consumer lithium battery drills. The possibility of overcharge was therefore unlikely as redundant systems protect against this. Over-temperature alarms were correctly displayed.

    Protection against cell failures is a great unknown. The FAA required smoke from such an event not to enter cabin or crew areas. This requirement seems to have also been satisfied, but the escape of gas (conducting plasma?) into the electronics bay poses serious risks.

    The photos shown two areas for concern. The main control electronics in the same compartment as the cells, it was hence disabled and destroyed very soon after the original event so any internal data was lost as well as significant reduction in system redundancy. The internal arcs, combustion and pressure caused the battery enclosure to burn through and expand close to rupture.

    With hindsight the following improvements could be considered:

    Providing an additional secondary enclosure with arc resistant lining, sufficient volume to attenuate overpressure and with a diaphragm to rupture and vent out of the aircraft.

    Dividing the primary battery enclosure to protect the electronics from damage and protect data for post event analysis.

    There appears to be adequate space for such a design change. There is no guarantee that catastrophic cell failures will not occur in Lithium batteries. The issue is what failure rate is acceptable and can such failures be contained so that there is a negligible risk of consequent damage. The present design seems to have failed these criteria.

  • 4
    comet
    Posted January 28, 2013 at 11:58 pm | Permalink

    The clearing of Japanese battery maker, GS Yuasa, is actually bad news for Boeing.

    If it had been found that GS Yuasa had made a bad batch of batteries, containing metal impurities, then that would be easily fixed by correcting the manufacturing process. But no metal impurities have been found.

    We also know the electronics were providing the correct voltage to the battery. Investigators are now going to have to look further up the chain, at the design of the system. That is going to be much more time consuming to correct.

  • 5
    comet
    Posted January 29, 2013 at 2:02 am | Permalink

    Reuters investigation:

    Japan intervened to fast track 787 launch.
    http://www.reuters.com/article/2013/01/28/us-boeing-dreamliner-japan-idUSBRE90R05C20130128

  • 6
    Ben Sandilands
    Posted January 29, 2013 at 7:00 am | Permalink

    James,

    I agree very much with your comments. In relation to technical details they are abundantly available to those who search for NTSB or NTSB 787 update, and in many of the articles linked to carry hyperlinks into such material.

    This is one of the advantages of on-line publishing, in that readers can click through not only to the nitty gritty, but past reporting or commentary that might not fit with what a reader knows or expects.

    Every now and then I put such material in large measure in the body of a post and invariably get criticised for cramming the post with material that readers can bring up themselves if they wish.

    Navigating the need for concise posts and detailed information is inevitably a compromise and my record in getting this right is far from satisfactory to many readers.

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