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Problems with the Dreamliner battery

by Greg Bernhardt
Tags: 787, batteries, battery, dreamliner, lithium, power
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jim hardy
#55
Feb13-13, 11:05 PM
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There's been some trouble. Probably one would have to play golf or go fishing with pilots and airplane mechanics to get the real story .

http://www.aviationweek.com/Article....542761.xml&p=1

Japan’s two biggest airlines replaced lithium-ion batteries on their Boeing Co 787 Dreamliners in the months before separate incidents led to the technologically advanced aircraft being grounded worldwide due to battery problems.

Comments from both All Nippon Airways, the new Boeing jetliner’s biggest customer to date, and Japan Airlines Co Ltd point to reliability issues with the batteries long before a battery caught fire on a JAL 787 at Boston’s airport and a second battery was badly charred and melted on an ANA domestic flight that was forced into an emergency landing.

ANA said it changed 10 batteries on its 787s last year, but did not inform accident investigators in the United States because the incidents, including five batteries that had unusually low charges, did not compromise the plane’s safety, spokesman Ryosei Nomura said on Wednesday.

JAL also replaced batteries on the 787 “on a few occasions”, said spokeswoman Sze Hunn Yap, declining to be more specific on when units were replaced or whether these were reported to authorities.

ANA did, however, inform Boeing of the faults that began in May, and returned the batteries to their manufacturer, GS Yuasa Corp. .....
AlephZero
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Feb14-13, 03:10 PM
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Quote Quote by jim hardy View Post
Probably one would have to play golf or go fishing with pilots and airplane mechanics to get the real story.
It's all shared information between the people who can actually make some use of it. Given the amount of air traffic world wide, you shouldn't be too surprised that there are "incidents" somewhere every day of the week, but most of them are no more "news" than the fact that one of your car tires got a puncture and had to be fixed - unless the tire blew and the car ends up upside down in a ditch, of course, which might make it into a "news story". And then some news reporter with a PhD in basket weaving discovers there are a million car tire puctures every year in the USA - shock horror, panic, "car tires are unsafe", etc, etc .....

FWIW we once had quite an argument with the FAA which started from "what's going on here - we AREN'T getting any reports of a particular type of failure from your engines. What are you hiding?", The answer was "nothing", but it took a while to convince them that our desgins were sufficiently different from the competition that they really never did fail that way.

(Note for pedants: I've no idea whether "a million" is the right number or not).
jim hardy
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Feb14-13, 06:54 PM
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I didnt mean to suggest a surreptitious coverup or conspiracy.. Sorry.

More along the line firsthand observations are always the best.

Information in a corporation flows much like water in a stream, and any cowboy will tell you : "Always drink upstream of the herd".

old jim
AlephZero
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Feb14-13, 07:31 PM
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I didn't think you were suggesting any conspiracy. But the information doesn't just go to the airilne or the plane maker. There are committees and safety boards run by organizations like the FAA and NTSB that have representatives from all the major players, and they get to see data across the whole industry, not just for their own products.

These can end up like Longfellow's poen - "Though the mills of God grind slowly, yet they grind exceeding small". For example a committee set up to investigate this http://en.wikipedia.org/wiki/United_Airlines_Flight_232 back in 1989 is still grinding away at improving inspection methods. One reason it's a slow process is the small amount of data to analyse - it gets about one new "data point" (i.e. somebody detects a potential problem at the manufacturinig stage) per year, and of course some of those turn out to be false positives.

But you won't find that level of information in the public domain, unless somebody leaks it.
AlephZero
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Feb15-13, 10:50 AM
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Polish airline LOT announces plans to reschedule summer services, keeping its 787s grounded until October. http://seattletimes.com/html/busines...reamliner.html

Airbus rules out Li batteries on the A350. http://www.bbc.co.uk/news/business-21477126
nsaspook
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Feb15-13, 10:59 AM
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Wow, that is really bad news for Boeing if they can't completely nail this problem down to a fixable root cause. I sure hope Boeing has a 'Plan B' that won't take a year of downtime to qualify a new electrical sub-system.
Dotini
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Feb15-13, 12:50 PM
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Quote Quote by nsaspook View Post
Wow, that is really bad news for Boeing if they can't completely nail this problem down to a fixable root cause. I sure hope Boeing has a 'Plan B' that won't take a year of downtime to qualify a new electrical sub-system.
Boeing management is currently feuding with its engineers. Perhaps a lengthy strike could allow force majeure to be invoked over the delivery schedule and any late delivery penalties.

We know the NTSB and FAA are looking not only into the specific battery woes, but also the design, manufacturing, and underlying certification processes are all up for review. In my humble opinion, all this will take roughly 18-24 months to be resolved.

Since industry analysts are well aware of these issues, it's remarkable how well the price of Boeing stock is holding up.

Respectfully submitted,
Steve
nsaspook
#62
Feb18-13, 12:02 PM
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http://seattletimes.com/html/busines...yndication=rss

The initial redesign includes a fireproof battery box, made of titanium or steel, several sources said. That will seal the cells, keeping moisture out and flames in.

It also includes a venting system that will directly evacuate to the outside any vapor and liquid flowing from the battery.

In the two recent battery overheating incidents, flammable liquid and vapor sprayed out of the battery and across the electronics bay where the battery sits, before reaching an outflow valve.

Longer term, the battery box will be enlarged to provide more separation between the battery’s eight cells, several sources said.

That will help ensure that overheating of one cell doesn’t spread to others — a so-called “thermal runaway” that occurred in both recent incidents.

The battery control system will have sensors to monitor the temperature and voltage of each individual cell rather than the battery as a whole, one source said.

And the same source said engineers are also working on using an inert gas such as halon or nitrogen to expel the oxygen generated when a battery overheats.
OmCheeto
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Feb18-13, 12:43 PM
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Quote Quote by jim hardy View Post
.... and any cowboy will tell you : "Always drink upstream of the herd".

old jim


So how much is this fiasco going to cost all of the parties involved?

And all because of an insignificant, pitiful battery.

This strikes me as pathetic beyond words.
Dotini
#64
Feb18-13, 12:59 PM
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We will know a little bit more by this evening's late news; but a "no" vote and strike authorization does not mean that a walkout is imminent. IF Boeing management doesn't agree to return to the bargaining table by the end of February then something will happen after the 1st week of March. A strike is a get-out-of-delivery-delay-jail free card, BUT I'm not sure that a strike trumps an FAA grounding order.

http://seattletimes.com/html/busines...ing787xml.html
Boeing has short and medium term plans. Real pain will ensue beyond 9 months.

Meanwhile, back in Everett, 787s are stacking up at the rate of 4 per month and 1 per month in South Carolina.

The original 787 Li-ion battery was certified on the basis that there would only be one "smoke event" per 10 million hours of operation. The 50 787s delivered only have about 50K hours of operation as of January 16, 2013, and have experienced 2 "smoke events".

Not root cause yet but little buggers called dendrites are suspect: http://seattletimes.com/html/busines...7probexml.html

Respectfully,
Steve
AlephZero
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Feb18-13, 03:21 PM
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Quote Quote by Dotini View Post
Boeing has short and medium term plans.
The short term plan seems to be "well, we haven't any idea what caused the problem, but hey, let's put the battery in a metal box with a pipe venting overboard to let the smoke out".

That must be a good plan. It's taken "hundreds" of Boeing engineers working "round the clock" to come up with it, according to their press releases.

Even that will take 3 months to certify and retrofit, assuming the FAA are prepared to sign it off. But I can't see the FAA signing anything off until the NTSB have issued a formal investigation report. The only promise date for that is "maybe we can issue a preliminary report by the end of February," but that will only be a record of the facts, not an analysis of the actual problem.

I'm inclined to believe LOT airline's time estimates (October at the earliest for a fix). They don't have anything to lose by being honest.
jim hardy
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Feb18-13, 05:46 PM
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Quote Quote by nsaspook View Post
http://seattletimes.com/html/busines...yndication=rss
"....The battery control system will have sensors to monitor the temperature and voltage of each individual cell rather than the battery as a whole,...."
What ? One sensor?
As sensitive as these things are to temperature,
IMHO it's very bad judgement to accept the time lag for temperature to transit beween an overheating individual cell and a single sensor that's monitoring the whole battery.
Somebody shoulda kaboshed that.
Those sensors need to be in intimate contact with their respective cells. Inside them if possible.

If that's what really happened, it is a symptom of too much delegation of design responsibility . And inadequate review.

But it's hard to believe.
So I'll wait on more info about the monitoring & control system architecture.
nsaspook
#67
Feb18-13, 10:06 PM
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I think the FAA and the NTSB believes Boeing played them for fools with the battery special conditions and will force a compete redesign with a different battery type before the plane will fly again. Just containing the fire is not really a option when you need the battery to fly the plane safely.

http://www.evworld.com/focus.cfm?cid=15

The FAA is on the hot seat. Five years ago, they accepted Boeing’s arguments and granted permission to use lithium-ion batteries on the Dreamliner, “if potential fire is contained and fumes vented”. They now have a dilemma – hurting an important domestic industry by doing their job, or becoming discredited if another problem occurs.
OmCheeto
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Feb18-13, 10:42 PM
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hmmmm

After offering to help Boeing with its lithium-ion battery problems, Elon Musk is somewhat raising the stakes. Musk, who heads both Tesla Motors and space exploration company SpaceX, has now called the batteries in the Boeing 787 "inherently unsafe" in an e-mail to trade publication Flightglobal.
ref

I've often whined about them using AA sized cells in electric cars. I just found out why they do that, on purpose:

For example, with seven thousand 18650 cells the surface area is roughly 27 square meters. If there were an imaginary set of 20 much larger cube-shaped cells that enclosed the same volume, the surface area would be only 3.5 square meters, more than seven times smaller. Surface area is essential to cooling batteries since the surface is where heat is removed; more is better. Also, because of their small size, each cell is able to quickly redistribute heat within and shed heat to the ambient environment making it essentially isothermal. This cooling architecture avoids “hot spots” which can lead to failures in large battery modules.
ref

I guess it made me crazy imagining trying to connect 7000 cells, or trying to locate one bad cell out of 7000.
Ptero
#69
Feb28-13, 05:09 PM
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Those sensors need to be in intimate contact with their respective cells. Inside them if possible.
That won't work. At least, it will not warn of a problem until the battery is in runaway mode. Why? Because the shorts start at points measured in sub-cubic mm volume. Sure, the sensor might pick up a rising temp indication, but in preventing runaway thermal episodes, you are depending on luck, not engineering.

Amazingly, Boeing, in full recognition of this fact and desparate to get the Dreamliner fleet flying again, proposed to the FAA a new containment box with stainless steel walls nearly one-half an inch thick with a tube venting super-heated gas (plasma) outside the plane at locations at the cockpit and near the trailing edge of the wings. I read this in the Seattle paper, and the reporter speculated that this was not really a good idea because the battery could possibly vent flames during fueling.

And when are the likely times for a runaway condition? On the tarmac during fast charging. I suspect this is exactly what happened to the JAL B-787. But that is not the most serious example the FAA has to deal with. The B-787 that landed with the battery box on fire in Japan came close to erupting into flames in the cockpit IN THE AIR. This could have brought down the plane, killing everyone on board.

I am perplexed at Boeing's response. Obviously, at this juncture, the Li-Cobalt batteries have to be replaced with some other safer type. All safer types require greater volume to produce an equivalent output. The space engineered and built for the box is not large enough so a nightmare retrofit will be necessary. This is a solvable problem but Boeing is in a serious pickle here, on one hand losing millions per day and on the other, having originally provided to the FAA the data and formal assurances on the Li-Co batteries. Not only are they eating crow and losing money, but they have embarrassed the FAA and likely also pissed them off, so a quick return to the skies for the Dreamliner is out of the question in the absence of political corruption (which is not unheard of) or a jiggered peer review (probably harder to pull off).

What is wrong with Boeing? I keep asking myself this. The Li-Co problem was well known. There is no excuse. Has Boeing done something to make their engineers less capable, as NASA did on the loss of a billion-dollar Mars probe when an engineer confused imperial with metric measurement? Was it brought about, perhaps, by government policy, such as hiring mandates? The Boeing incident is even more peculiar because many engineers were involved in this decision. It was not just one who made the mistake, as in the NASA case. I don't know how badly this will hurt Boeing. It will be a deep wound. The only thing I'm certain of is that we taxpayers will end up paying for it in some future military contract.
Ptero
#70
Feb28-13, 06:19 PM
P: 32
Digging, I found this. Not sure what to make of it. For now, a coincidence.
-----------------
Updated Boeing Statement on 787 Dreamliner ZA002 Incident

EVERETT, Wash., Nov. 11, 2010 /PRNewswire/ -- Boeing continues to investigate Monday's incident on ZA002. We have determined that a failure in the P100 panel led to a fire involving an insulation blanket. The insulation self-extinguished once the fault in the P100 panel cleared. The P100 panel on ZA002 has been removed and a replacement unit is being shipped to Laredo. The insulation material near the unit also has been removed.

Damage to the ZA002 P100 panel is significant. Initial inspections, however, do not show extensive damage to the surrounding structure or other systems. We have not completed our inspections of that area of the airplane.

The P100 panel is one of several power panels in the aft electronics bay. It receives power from the left engine and distributes it to an array of systems. In the event of a failure of the P100 panel, backup power sources – including power from the right engine, the Ram Air Turbine, the auxiliary power unit or the battery – are designed to automatically engage to ensure that those systems needed for continued safe operation of the airplane are powered. The backup systems engaged during the incident and the crew retained positive control of the airplane at all times and had the information it needed to perform a safe landing.

Molten metal has been observed near the P100 panel, which is not unexpected in the presence of high heat. The presence of this material does not reveal anything meaningful to the investigation.

Inspection of the surrounding area will take several days and is ongoing. It is too early to determine if there is significant damage to any structure or adjacent systems.

As part of our investigation, we will conduct a detailed inspection of the panel and insulation material to determine if they enhance our understanding of the incident.

We continue to evaluate data to understand this incident. At the same time, we are working through a repair plan. In addition, we are determining the appropriate steps required to return the rest of the flight test fleet to flying status.

Boeing will continue to provide updates as new understanding is gained.

Contact:

Lori Gunter
787 Communications
+1 206-931-5919

SOURCE Boeing
http://boeing.mediaroom.com/index.php?s=43&item=1515
jim hardy
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Feb28-13, 06:44 PM
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And when are the likely times for a runaway condition? On the tarmac during fast charging.
ptero - that was my point. Batteries warm up during charge and that needs to be sensed early not late. One overtemperature sensor for the whole pack(if indeed that's what they did) would be, well, indicative of amateurism. One cannot assume all cells are equal tempereature, a single sensor will only tell you that one cell is afire or nearly so and about to spread....
My reactor had fifty-one thermocouples immediately above core to monitor for local temperature anomalies. That's in adition to redundant bulk temperature sensors for control and protection.

but i am of the same thoughts as you on this point - airplanes should use a safer battery chemistry.

old jim
Ptero
#72
Feb28-13, 09:44 PM
P: 32
Jim, I was pointing out that, based on the literature I have read, heat sensors are not effective in finding the point of failure inside a Li-Co batttery. Nothing is. The only way to tell what happened is after the fact, with an "autopsy," if you will. But sensors will only provide an average temperature while likely missing entirely the "hot spot" as it develops.

My point is that people can easily be misled into thinking that temperature sensors on Li-Co batteries can provide the same kind of safety assurance they have demonstrated on metal-hydride, nickle-cadmium and even lithium-magnesium types. But Li-Co is a strange beast. When they work, they work really well and lull you into a false sense of security. It appears to me that we have gotten way ahead of ourselves in thinking that the larger ones can be managed safely.

Part of this false sense of safety comes from the design of thermal-triggered open circuits designed into each cell. A good discussion begins here around page 25 of Lithium-Ion Batteries Hazard and Use Assessment - Final Report:

http://www.nfpa.org/assets/files/PDF...riesHazard.pdf

Unfortunately, the reliability of this feature does not prevent a thermal runaway if it is in progress, but rather is intended to prevent too rapid discharge or charge conditions from damaging or degrading the battery.


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