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 ...
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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