Thursday, February 7, 2013

Boeing 787 Battery Fire: Thermal Runaway from a Short-Circuited Cell, Says NTSB

So that's for JAL's battery. No word yet on ANA's. There is no mention of multiple occasions of JAL and ANA exchanging batteries throughout last year.

From ABC News (2/7/2013):

The battery fire that grounded Boeing's Dreamliner back in January was started in one of eight battery cells that make up the lithium-ion battery used to power the plane when all other power sources fail, NTSB investigators said at a news conference today.

The single cell showed signs of short circuiting that led to thermal runaway -- a chemical reaction during which a rising temperature leads to increasingly higher temperatures, and spread to the rest of the battery, the board reported.

The NTSB has ruled out external short circuiting as a cause for the problems.

"Boeing has indicated that these tests that were conducted prior to certification showed no evidence of cell-to-cell propagation or fire in the battery," Deborah Hersman, chairwoman of the NTSB, said today in Washington. "However, our investigative findings with respect to the event battery show that when a short circuit did occur, it resulted in cell-to-cell propagation in a cascading manner and a fire."

...The certification tests by Boeing found that the likelihood of "smoke emission" from one cell and then a spread to other areas would occur in less than one out of every 10-million flight hours. The 787 currently has only 100 thousand flight hours, and already there have been two smoke events -- one resulting in a fire.

...But the NTSB said Boeing failed to mitigate the hazards and must review not only the battery problem but its testing that provided false conclusions.

(Full article at the link)

It looks like both Boeing and GS Yuasa have some explaining to do, but to say the "testing ... provided false conclusions" is a bit harsh. As Boeing says, in the article:

"We provided testing and analysis in support of the requirements of the FAA special conditions associated with the use of lithium ion batteries..."

In other words, Boeing provided exactly what the regulator wanted.

(Sound familiar?)


Anonymous said...

I agree, it sounds familiar. Boeing complied with the FAA requirements, which turned out to be inadequate.

This kind of thing happens more often than we want to know, I'm afraid. Both the public and industry have a tendency to assume that the regulatory agencies know the best and blindly follow their standards to the letters, again assuming those are the only thing one needs to fulfill in order to assure safety, etc.

Have anyone ever read a book called "Black Swan: The Impact of the Highly Improbable" by Nassim Nicholas Taleb? He explains the flaw in the standard method for calculating catastrophic failures. I also came across with a blog that explained Taleb's theory applied to the conventional (mis)calculation of a risk priority number (RPN) in FMEA (Failure Modes and Effects Analysis) in relation to the Fukushima nuclear incident:|mt:2|

TechDud said...

I'll bet that they are within a whisker of the answer. :)

netudiant said...

Boeing historically has had the smarts to understand that the requirements are only a guide, that the real world is much more unforgiving than the regulators and that the company is best served by meeting internal standards that are often far more exacting and specific than any FAA regulation. Unfortunately, there is not, afaik, an internal requirements set dealing with batteries and their chargers. So it may well be that Boeing was just blindsided by this debacle. They will not be caught out this way again, the damage is just too great. But their design verification process was obviously deficient in this case.
As members of the travelling public, we can only hope that no similar shortcomings are lurking elsewhere in this innovative design.

TechDud said...

Perhaps batteries utilizing technology that is claimed to be inherently safe would be in order.

Better yet, how about one that could have extended power during the StuporBowl?

TechDud said...

My mistake; 19.8V packs are incorrect for a 22.2V system.

Counterfeit parts warning (PbSO4 batteries):

"In a little-noticed test in 2010, the F.A.A. found that the kind of lithium-ion chemistry that Boeing planned to use — lithium cobalt — was the most flammable of several possible types. The test found that batteries of that type provided the most power, but could also overheat more quickly. "
"The batteries’ maker X-rays each battery before shipping to look for possible defects.

But some battery experts said that scans might be unable to detect minute anomalies in the battery, like trapped micro-shavings in any of the tightly wound conductive material used in each battery’s eight cells."
___quoted from:

Also note that thermal sensing would have a lag-time if external to a cell, especially during thermal runaway.

TechDud said...

Quote: "Questions about the cooling of the Boeing 787's batteries came up again this week, as Tesla Motors CEO Elon Musk publicly stated that the plane's large pack design is a risky one.

"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," he wrote in an email to "Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature."

Tesla uses lithium-ion battery packs in its Tesla Roadster and Tesla Model S vehicles. Its design involves 6,000-7,000 small lithium-ion cells. Musk told Flightglobal that the cells are separated in a way that makes them less likely than large cells to suffer from thermal runaway events."


"Even at low temperatures, the Boeing system could still have been at risk, according to Cairns. "When the plane is at altitude, the air is less dense," he told us. "So even if it's cooler, the less dense air may not have adequate heating capacity to provide enough cooling for the battery. If they don't have active cooling, then I question the adequacy of the cooling arrangement."

Boeing uses eight lithium cobalt oxide cells in its battery packs. According to experts, the cobalt oxide chemistry is known to have higher energy densities than other forms of lithium-ion, so it needs an active cooling system.

Boeing representatives told us that they are not aware of an active cooling system for the 787 batteries. "Obviously, there were multiple backups associated with the battery to ensure the system was safe against overcharging and overdischarging," Birtel said. "But there was not a specific cooling system associated with the battery."

Cairns called battery management ICs (to monitor voltage and current) an important part of a safe pack, but he also said energetic batteries often need more than that.

"The electrical system that manages the battery is not a complete battery management system," he said. "In my view, a complete battery management system includes the dispersion of any heat that is generated by the operation of the battery. Just having protective circuits is fine, but it is absolutely insufficient." "

___quoted from:

TechDud said...

From the files of the Japan Transport Safety Board concerning an incident with a Dreamliner's batteries:


"Only one electric car has been built in volume using CoO2 cells, and that's the Tesla Roadster. Only 2,500 of those cars will ever exist."

___quoted from:


"Metal particles from a defective manufacturing process led to overheating in Apple and Dell products several years ago, resulting in massive recalls"

___quoted from:

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