Green Car Congress  
Go to GCC Discussions forum About GCC Contact  RSS Subscribe Twitter headlines

« Liox Power reports first operation of a Li-air battery with a straight-chain alkyl amide electrolyte solvent; new direction for Li-air research | Main | DOE seeking comment on draft $50M solicitation for new projects over 11 areas of interest to improve vehicle performance and decrease fuel consumption »

Print this post

NTSB issues seventh update on JAL Boeing 787 battery fire investigation

1 February 2013

The National Transportation Safety Board released the seventh update on its investigation into the 7 January fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.

The auxiliary power unit battery, manufactured by GS Yuasa, was the original battery delivered with the airplane on 20 December 2012. It comprises eight individual cells. All eight cells came from the same manufacturing lot in July 2012. The battery was assembled in September 2012 and installed on the aircraft on 15 October 2012. It was first charged on 19 October 2012.

Examination and testing of an exemplar battery got underway earlier this week at the Carderock Division of the Naval Surface Warfare Center laboratories in West Bethesda, MD. The tests consisted of electrical measurements, mass measurements, and infrared thermal imaging of each cell, with no anomalies noted. The cells are currently undergoing CT scanning to examine their internal condition. In addition, on Thursday, a battery expert from the Department of Energy joined the investigative team to lend his expertise to the ongoing testing and validation work.

In Seattle, NTSB investigators and Boeing engineers examine the type of lithium-ion battery used on the Boeing 787 to start the auxiliary power unit and to provide backup power for flight critical systems.

NTSB investigators were made aware of reports of prior battery replacements on aircraft in the 787 fleet, early in the investigation. As reported Tuesday, Boeing, a party to the investigation, is providing pertinent fleet information which investigators will review to determine if there is any relevance to the JAL investigation.

An investigative group continued to interpret data from the two digital flight data recorders on the aircraft, and is examining recorded signals to determine if they might yield additional information about the performance of the battery and the operation of the charging system.

Next week, the NTSB battery testing team will initiate a non-invasive “soft short” test of all cells of the exemplar battery. This test will reveal the presence of any high resistance, small or “soft” shorts within a cell. Also, an NTSB investigator will travel to France with the battery contactor from the JAL event battery, for examination at the manufacturer. The battery contactor connects a wiring bundle from the airplane to the battery.

Investigators are continuing their work in Washington and Japan and the team in Seattle continues to observe the FAA-led review of the certification process for the 787 battery system. The flow of information from these observations helps to inform NTSB investigative activity in the US and around the world.

February 1, 2013 in Brief | Permalink | Comments (18) | TrackBack (0)

TrackBack

TrackBack URL for this entry:
http://www.typepad.com/services/trackback/6a00d8341c4fbe53ef017d40ad8360970c

Listed below are links to weblogs that reference NTSB issues seventh update on JAL Boeing 787 battery fire investigation:

Comments

What a mess - 50 planes grounded, 7 a month coming out of the factories and no solution.
All to halve the weight of 40 KG of batteries.

oops.
I wouldn't like to be half way across the Pacific when one of those goes on fire.

Tesla's battery packs may do a better-safer job?

Are 8,000 small cells inherently safer than 8 large cells.

Has Boeing chosen the safer technology?

Is NASA using safer very light cells?

Off the top of my head, it looks like a 10-cell series string of LiFePO4 cells would have approximately the correct voltage to substitute for this battery.

Taking this 12.8 V 40 ah pack from Batteryspace as a baseline (40 Ah, 6.7 kg), an all-up weight would be on the order of 5 times as much or 34 kg.  If 9 cells would still meet the voltage specs, chop that down to about 30 kg.  It looks like the iron phosphate chemistry could be used in a drop-in replacement for the GS Yuasa battery.

The battery wasnt the cause as they already found out. Its somewhere else in the system.

Not true.  They are still examining batteries, not just the charging systems.  Also, a more rugged battery could take mistreatment without failure.

@EP, while you might get a voltage and current drop in replacement, integrating the battery and controls etc. into the plane would be a considerable undertaking.
I agree on the battery being a large part of the problem. The batteries went on fire.
If that happened 3 hours out over the Pacific, we would probably lose the plane.
It is ironic that a small thing such as 40 Kgs of batteries could cause so much trouble.

You wouldn't have to lose voltage, just increase the number of cells in series.  All Li-ion chemistries have wide voltage changes between discharged and full charge, so the connected equipment is already going to be able to deal with any small differences.  The only thing that needs to change is the charging cutoff voltage.

The chemistry would change everything.  A LiCoO2 electrode might be pushing it at a charge rate of 1 C, but LiFePO4 might be able to handle more current than the charging system is capable of generating.  That would be a margin of safety unattainable through technical means; if the battery can charge at 10C and the charging system is incapable of more than, say, 3C, you cannot over-stress the battery.

Cant believe a bunch of these werent burnt down in testing for three years?? Did UL sign off on this?

That's why I would not rule out sabotage, Fred.  If the charge-controller software can be hacked (and there are hundreds of loadable software modules running various parts of the 787, updated by computers plugging into the data bus), there's plenty of potential for doing damage to Boeing without ever touching an airplane.

What is Airbus using?

I believe the new Airbus A350 uses almost identical Li-Ion batteries but from a different supplier than GS Yuasa.

Airbus argues that their system is safe because of multiple minor but important differences they are likely to not have the problem - whatever that problem is.

Sabotage is very unlikely - particularly after this far into the investigation.

And it makes NO sense to claim a heavier battery would solve the problem.

1. They don't know the cause.

2. When they do determine the cause/problem it may be mitigated adequately by periodic checks or replacement of all batteries from a given lot. Such solutions may allow operation to resume soon.

3. If the solution requires a modification of the system, it will take longer.

4. If the battery must be replaced by another type, it will take longer yet - the battery must interface with many systems and be proven safe (obviously). – and what about the main AC battery? – I believe they are identical.

5. To say the existing battery problem would not exist if they made the battery 10 pounds heavier is irrational - it assumes the problem is known.

Of course it will be trivial if the battery must be replaced by a different design and the replacement is 10 pounds heavier (one less "carry-on"), but the Space Shuttle was grounded for almost 3 years while changes to improve booster safety were made and validated even though the cause/problem was well defined relatively quickly

@Engineer-Poet Investigating batteries does not mean that the problem is in batteries
@ToppaTom Point one is right on. Everything else is not so important. The problem is that after so many weeks of investigation there is no conclusion. Somewhere on the way Boeing lost a very important expertise. It is embarrassing that the company with so much resources makes so dangerous mistakes. It is also says a lot about NTSB which could not deliver the results in much shorter period of time.
Has somebody heard/read that they are doing Power System investigation?

FTA:

An investigative group continued to interpret data from the two digital flight data recorders on the aircraft, and is examining recorded signals to determine if they might yield additional information about the performance of the battery and the operation of the charging system.

It is in Boeing financial interest to find a safe solution 'very soon' even if it means a return to older batteries used in the 777 or 747 or the new batteries used in the Airbus A-380 or A-350?

Criticism of the lack of investigative progress is mounting. Many investigators are admitting that since they do not know the cause of the short circuits and overheating they are no closer to identifying the root cause than at the start.

Boeing has petitioned the FAA to conduct test flights in case flight conditions might be part of the cause, but has been put off.

Among many contingency plans, Boeing is considering a containment box around the battery.

But this is risky; the NTSB is frightened of fires on aircraft and if Boeing aggressively pushes this solution, the NTSB may discover that aircraft engines use fire to burn jet fuel.


This may strike you as strange, but the FAA knows that.

The FAA also has specifications for the devices to detect fire in an engine housing.  One very common device is a wire inside a coaxial stainless tube, with the gap filled by solidified salt.  If the tube gets hot enough to melt the salt, the wire shorts to the outer tube; if something burns through the tube, continuity through the wire is lost.

No matter what will be found on the investigation, what will be needed are:

1. Multiple temperature sensors embedded within the battery pack to stop currents from going into or out of the pack once a critical temperature has been reached.

2. Equally important, a fire extinguishing system to shut down electrical fires should be installed on all critical areas. In a car, you can stop right away to get out of an electrical fire, but in an aircraft, you don't have that option right away.

For those who are sstill intersted here is the latest report. http://www.ntsb.gov/investigations/2013/boeing_787/JAL_B-787_2-7-13.pdf
Now I am totally convinced that this is system integration issue. They must resume experimental flights ... and turn to real experts

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Green Car Congress © 2014 BioAge Group, LLC. All Rights Reserved. | Home | BioAge Group