Wednesday, February 6, 2013

NTSB Chief Deborah Hersman on Boeing 787 Battery Fire: Plane Batteries Not Necessarily Unsafe

She says NTSB still doesn't have answers why the lithium-ion batteries by Japan's GS Yuasa caught fire in ANA and JAL, but as long as there are safeguards in place we shouldn't worry too much.

(and nuclear reactors that melt down are not necessarily unsafe as long as there are safeguards in place...)

From AP (2/6/2013; emphasis is mine):

NTSB: Plane batteries not necessarily unsafe
NTSB chairman: Lithium batteries not necessarily unsafe in aviation but safeguards needed

WASHINGTON (AP) -- Despite a battery fire in one Boeing 787 Dreamliner and smoke in another, the type of batteries used to power the plane's electrical systems aren't necessarily unsafe — manufacturers just need to build in reliable safeguards, the nation's top aviation safety investigator said Wednesday.

National Transportation Safety Board Chairman Deborah Hersman said she doesn't want to "categorically" rule out the use of lithium ion batteries to power aircraft systems, even though it's clear that safeguards failed in the case of a Japan Airlines 787 that had a battery fire while parked at Boston's Logan International Airport last month.

"Obviously what we saw in the 787 battery fire in Boston shows us there were some risks that were not mitigated, that were not addressed," Hersman told reporters in an interview. The fire was "not what we would have expected to see in a brand new battery in a brand new airplane," she said.

The board is still weeks away from determining the cause of the Jan. 7 battery fire, Hersman said.

The 787 is the first airliner to make extensive use of lithium batteries. Aircraft makers view lithium batteries, which are lighter and can store more energy than other types of batteries of an equivalent size, as an important way to save on fuel costs. The Airbus A350, expected to be ready next year, will also make extensive use of lithium ion batteries. Manufacturers are also looking to retrofit existing planes, replacing other types of batteries with lithium ion.

But lithium batteries are more likely to short circuit and start a fire than other batteries if they are damaged, if there is a manufacturing flaw or if they are exposed to excessive heat.

..."What happens is that when an aircraft is certified it basically gets locked into the standards that were in existence at the time," Hersman said. Oftentimes, tougher standards will come along later, but aren't applied to already-approved aircraft designs. "Those are issues we do look at regularly in our investigations and it is something I'm sure we will be focusing on with the battery," she said.

Investigators have been working very closely with the FAA on a review the agency has under way of its sanctioning of the 787's certification for flight, Hersman said. The FAA awarded the certification in August 2011.

"We are evaluating assessments that were made, whether or not those assessments were accurate, whether they were complied with and whether more needs to be done," she said. "I think that is important before this airplane is back in the air, to really understand what the risks are and that they're mitigated effectively."

(Full article at the link)

From the article, the issue of safety seems to be just the matter of whether the certification is properly issued by the government bureaucrats. As long as that is properly done, the plane should be safe.

The parallel to things nuclear is obvious.


netudiant said...

The NTSB is backing off its initial stance that the charger design was ok, so it had to be a battery problem. Since then, there have been reports of many instances, around 100 thus far, of severely undercharged batteries found in 787s, often because service mechanics failed to close the access doors to the fuel tanks, so the systems remained energized until the batteries run down.
Lithium batteries need to be kept within a range of charge from 20-100% to perform predictably. Allowing the battery to go outside that space can have serious results, as Boeing has now discovered. The implication is the engineering reviews were not sufficiently aware of real world behaviour, so an inadequate design was approved for service. My guess is that the revised 787 manual will require the technicians to pledge their firstborn that everything is off before they leave the airplane, because that is really the critical xhange that is required. There may be a more far reaching redesign later, but that is not feasible within a few months.
The Fukushima link is clearly in the conflict between the real world and the specifications.
Fukushima was not supposed to have a 15 meter tsunami any more than the 787 batteries were supposed to be discharged to the point of needing factory service in Japan. Boeing probably has more blame, because they got some early warning that there was a battery system problem, while poor TEPCO just got hit out of the blue. However, both shared the affliction that they believed the job is to meet the spec, rather than to prosper in the real world.

Anonymous said...

"Plane batteries not necessarily unsafe"

Yeah, guns are not necessarily unsafe but they sure manage to kill a lot of people every year.

This is industry speak for "nobody can afford to keep these planes grounded so let's close our eyes and hope for the best"

Japan is doing the same thing with their backtrack on dropping nuclear power.

Anonymous said...


Out of the blue..huh. Large earthquakes and massive tsunamis don't happen very often, but they are predictable with in a certain time frame. And scientist predicted one for this area. It has happened before, so it's going to happen again. That is why the Mayor of Fudai spent time and money to build a hugh tsunami wall, thought of as useless and expensive at the time, to protect the city. The town survied and houses barely got wet.

Do you work for TEPCO?

arevamirpal::laprimavera said...

RJ, netudiant is a long-time reader of this blog and has contributed valuable information and insight. Your last comment is not warranted.

netudiant said...

Hi Anonimous 5:17,

You are right that there was precedent for large tsunamis in the Japanese historic records and that TEPCO deserves blame for inadequate preparation. Still, the really large quakes are very infrequent, the last similar one was about 1000 years ago, so they were caught out by using a short history rather than the full data set to spec their seawall. That is why I said 'out of the blue'. Your own comment about Fudai really deserves more consideration. If the Mayor was given serious flack for spending lots of money on a sea wall, a construction project which was probably pretty helpful to the town econonomy, how likely do you think it would have been that TEPCO shareholders would have cheered a similar but much larger wall as would have been needed for Fukushima?Arevamirpal:laprimavera, thank you for the kind comments. This forum is a real resource and we all should try to maintain cordiality on it.

Anonymous said...

Lithium batteries should never be run down to anywhere near 20%! if they are, severe damage results. LiPO batteries in particular should never drop lower than 3v per cell. An automatic cut out should be in place to protect the batteries from being over-discharged at the very least. I find it hard to believe (although I'm not over surprised these days) that such basic errors can be made at design and specification level!!!

Anonymous said...

What does "not necessarily unsafe" actually mean? Reads like a "cover my ass" phrase. I guess nuke plant are "not necessarily unsafe" too. It could become the nuke industry's new motto.

Ageless Yankee said...

RE Netudian's comment about maintaining battery charge levels between 20% and 100%.

I would expect a consistent undercharging to reduce the AH capacity of the battery, but not overheat it. Additionally, the low-charge hypothesis doesn't explain why the fires seem to be occurring within 100 hours of the last maintenance check.

I could see a situation where the battery was largely discharged and then damaged during charging in an attempt to "bring it back from the dead".

This hypothesis points back at the charging system and raises the question of whether there is a common APU update installed on each of the airplanes during the maintenance check.

Ageless Yankee said...

RE: Anonymous' suggesting that the battery be protected from excessive discharge. That's good design practice for consumer goods, but not backup airplane systems.

When the main engines quit, primary AC power is interrupted and the APU attempts to start and pick up the load. You may recall the 787 being referred to as an "electric airplane". The value of having (relatively) full AC power in a gliding airplane with electrically powered primary controls outweighs the risk/consequences of flattening the APU start battery. The flight crew would gladly sacrifice the APU start battery in order to get the APU started in this situation.

Anonymous said...

Normal Littium-Ion batteries do not catch fire on use. But these 787 batteries did and on several occasions. One can strongly conclude that THESE batteries used by 787 ARE UNSAFE!. What is Wrong with people ?. It is clear and yet she wants to tone down the message. If she sits on those batteries and it catches fire, you can bet she will scram rather than get her ass BURNED!. Only in the US can you get such incompetent managers!.

Anonymous said...

Hi ageless, in which case lithium chemistry batteries are unsuitable to the application! Over-discharge can cause overheating leading to the battery letting copious quantities of magic smoke out (or worse). Once the magic smoke has been let out of the battery it'll never work again... ;)

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