Posted on 02/07/2013 11:13:13 AM PST by jazusamo
A short circuit inside one cell started the 787 battery fire, and assumptions used to certify the battery system proved wrong, the NTSB said Thursday.
The National Transportation Safety Board (NTSB) has pinpointed the start of the 787 Dreamliner battery fire on a parked Japan Airlines jet a month ago today as a short circuit inside a single cell.
The agency still hasn’t identified the cause of the initial short circuit but has narrowed down the suspects.
Details provided by the NTSB make clear that Boeing will have to redesign the battery for a long-term fix.
In addition, the NTSB pointed to failures in the airplane certification process conducted by Boeing and the Federal Aviation Administration (FAA), which failed to identify the hazards revealed by this incident.
“The assumptions used to certify the battery must be reconsidered,” said NTSB chief Deborah Hersman in a detailed press briefing. “Our task now is to see if appropriate layers of defense and checks were built into the design, certification and manufacturing process.”
The overheating that started in cell 6 of the eight-cell battery spread to all the others and caused the fire, Hersman said.
(Excerpt) Read more at seattletimes.com ...
We use similar batteries where I work. They go on charging runaway about once a week. First the smell begins. Then the heavy sulphur smell feels heavy in your lungs. Then the smoke begins. At that point I throw the disconnect from about a hundred yards away and wait until the stink clears. Then I call the battery company who comes out and replaces the unit for about $23,000 dollars. It’s a good business to be in. That is until someone decided to get them approved for an airworthiness application / use! Vehicles on the ground have a use profile of maybe two hours a day. Aircraft run 24/7 until a maintenance cycle.
Good points, I’m amazed they were approved for airliners.
Not only are vehicles used less but if an incident occurs you can stop and get out but that’s kinda difficult at an altitude of 35,000 ft.
http://asq.org/qualitynews/qnt/execute/displaySetup?newsID=15287
Attention is now being focused on the circuitry controlling battery current flow. Don't know who designed those components.
http://asq.org/qualitynews/qnt/execute/displaySetup?newsID=15287
Attention is now being focused on the circuitry controlling battery current flow. Don't know who designed those components.
Have you considered lead-acid or nickel-iron replacements?
Over 20 years ago we used lithium batteries in offshore submersible seismic equipment. They blew up all the time. Luckily it was usually at night sitting on the rack instead of while someone was handling the equipment.
Being smart or correct is not a valuable commodity in a plant. Being safe and approachable seems to be what they want. I just keep stuff running electrically.
*sigh* ain’t that the truth.
(s) a process engineer...
PS I hope no one is killed or permanently injured in the inevitable major fire.
Different materials can be used in these batteries, some safer than others. Based on information posted on its website, Boeing supplier GS Yuasa appears to be using lithium cobalt oxide cathode material, which is the original material used by Sony.
“From a safety point of view, that’s not the best,” said Ji-Guang Zhang, a researcher at the Pacific Northwest National Laboratory in Richland. He said cobalt oxide batteries ignite at lower temperature than lithium batteries made with other materials, such as iron phosphate.
Supplier GS Yuasa declined to discuss whether the batteries in question use cobalt oxide and referred questions to its partner Thales Group, which didn’t promptly respond.
Sorry for the double post. Slow link today.
Anyone knows why the need two huge (for aircraft) battery packs? Seems to me once the APU is started you don’t need that much juice. Same, same for the engines. They each have dual generators.
Not much technical info on the Boeing site.
Maybe it's extra redundancy for all the electronics. Even small aircraft with glass cockpits have dual alternators and batteries.
The control surfaces are electrically operated. What do you do if the fuel is contaminated or gone, and the APU won't start?
Well, DUH!
Even my R/C Helo instruction manual has a 2 page warning about the lithium batteries must be watched at all times during charging because they are prone to fires.
The FAA really doesn’t do much in thir certifications. They read practically no documents, test nothing, and take the word of whomever provides the docs that the docs accurately reflect the actual system.
Charred to a crisp: The burnt out remains of the lithium battery from a Boeing 787 which investigators are examining in Japan.
Grounded: The fire on board an All Nippon Airways flight forced the plane to make an emergency landing last month.
Damage: A ground wire which was attached to the burnt battery is showed charred, frayed and broken.
Thanks for posting these pics.
I saw one pic shortly after the incident of the battery pack but nothing this close-up or graphic.
It’s a miracle this didn’t turn into a disaster.
And there's the heart of the problem.
When I worked there 30 years ago, Boeing equipment was designed and largely built by Boeing personnel.
Boeing management, in its infinite wisdom, has decided that design, testing and manufacturing can be "subbed out", with major components assembled like tinker toys. The brilliance of their MBAs (Master Bullshit Artists) is clearly visible in the 787.
When we built the prototype wings for the 767 (in Everett, Washington), they broke at 115% of the design breaking load. My group designed a good part of the tooling. But then we built stuff to work, not to be the lowest cost bidder.
Pictures from this article today:
ram air turbine!
The next step, but they weigh more.
Not an issue on a factory floor.
Most aircraft only have one battery whether glass cockpit or not. In an emergency a ram air turbine provides backup electrical and/or hydraulic.
Based on the limited info I have seen the 787 has two humongous battery packs.
We have been known to fix the issue and then pretend we don’t know how it happened.
As a process engineer, sometimes that is the only way.
Heck, I’ve even fixed the issue without knowing how I did it, or the reason it worked.
Worse, I know of two ways brightness of LEDs was improved early on, my way which causes a 70% improvement, and the way a later colleague improved it where he worked.
The methods are exactly opposite.
When it's the latest multi-axis servo controlled foo-foo machine installed as some part of a complex business arrangement involving funding sources, grants, matching funds, etc....I replace fuses, reset overloads, rehome axises, make PLC edits, install load resistors, and of course the "It was a loose wire" problem solving choices. That's about it.
And I don't know about anyone else, but I loathe 24volt control systems! They are weak, hang up from dirty contacts, and generally suck. I prefer the good o'l 120V control systems that work every time without beating on them, blowing out door switches and auxiliary contacts, etc...
In-house gives you control (and responsibility) for all phases of the design and manufacturing process. But it can be pretty expensive as all that specialized design and manufacturing expertise has to be kept busy and that can be difficult.
Subcontracting the work out allows the prime contractor to reduce in-house investment in staff and equipment. With proper design reviews, quality control measures, warranties, etc. good quality parts that meet design requirements can be produced. In addition, in comparison to the in-house staff, a subcontractor specializing in a particular functional area or component... say, hydraulic pumps...can develop a much greater depth of expertise through successful completing many more projects.
Aye, but there's the rub. Depending overmuch on that subcontracted expertise can lead to complacency. The subcontractor may begin to think that all jobs are simply variations on a common theme. The prime contractor may begin to put too much confidence in the subcontractor's expertise. In this case, GS Yuasa is a sub to a sub, Thales. So you may have two levels of relying on someone else’s expertise at play here (Boeing to Thales, Thales to GS Yuasa).
If, as Jazusamo posted, the issue comes down to the specific type of lithium battery selected (lithium cobalt oxide), it is going to be very interesting to see who made the recommendation to adopt that battery type and what kind of development and certification testing was done on the batteries and their control circuits.
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