RottenRay From United States of America, joined Jun 2010, 267 posts, RR: 0 Reply 1, posted (3 months 3 weeks 1 day 15 hours ago) and read 33246 times:
DocLighting writes:
" If there is, say, severe turbulence, it could navigate around the compartment that way."
Doc, you've taken blood samples - they're thinner than the electrolyte goo you're talking about. This stuff is not magically sticky in a picture and later capable of gymnastics in turbulence.
Also, just how turbulent are you talking about?
I don't see ANY liquid which is already stuck to something changing its direction in a major way with, say, a 2g event. I suspect that we'd have other issues to worry about at that point.
And, frankly, positing a battery meltdown followed by severe turbulence is something best left to Hollywood.
Really and truly, these situations just don't line up like that. Outside of Hollywood, that is.
liftsifter From United States of America, joined Feb 2008, 237 posts, RR: 0 Reply 2, posted (3 months 3 weeks 1 day 15 hours ago) and read 33244 times:
Has John Leahy made a comment at all about the grounding and how it may affect the A350 program?
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 3, posted (3 months 3 weeks 1 day 12 hours ago) and read 32687 times:
Some of the comments in the previous thread before it was locked are unbelievable!
"When has the FAA or NTSB ever been proactive?"
Well -- they are being proactive right now! Grounding the battery system and thereby the aircraft until they can be sure the root cause issues are identified and fied, before something disastrous occurs.
"It is all just politics".
In other words, Obama is to blame. Right. Boeing is based primarily in two states which helped Obama get re-elected -- Washington and Illinois. But Obama wants to screw them?
Guys -- we need to take a step back, read the NTSB statement, and just calm down and accept that the grounding wasa prudent, proactive step given the two incidents just 9 days apart, involving a new system and technology that had only recently been certified but hadn't really stood the test of time and extensive usage yet. That is exactly the right thing they did. And I love Boeing and its products as much as anyone else.
Braybuddy From Ireland, joined Aug 2004, 5282 posts, RR: 35 Reply 4, posted (3 months 3 weeks 1 day 12 hours ago) and read 32601 times:
Quoting RottenRay (Reply 1): And, frankly, positing a battery meltdown followed by severe turbulence is something best left to Hollywood.
Murphy's Law. And aviation probably supplies one of the best (or worst) examples of same with the KLM/Pan Am collision at Tenerife in 1977: a bomb had exploded earlier at Las Palmas and the aircraft were diverted to Tenerife. Then you had the fog, the absence of ground radar, the misheard ATC instructions and the blocked-off taxiway. Had one of those events not occurred there would have been no collision.
Unflug From Germany, joined Jan 2012, 187 posts, RR: 0 Reply 5, posted (3 months 3 weeks 1 day 12 hours ago) and read 32582 times:
Quoting RottenRay (Reply 1): Really and truly, these situations just don't line up like that. Outside of Hollywood, that is.
Unfortunately reality offers sometimes more phantasy than hollywood. Take almost any air crash investigation and you will find situations have lined up in ways not to be expected...
DocLightning From United States of America, joined Nov 2005, 16808 posts, RR: 57 Reply 6, posted (3 months 3 weeks 1 day 12 hours ago) and read 32533 times:
Quoting RottenRay (Reply 1): Doc, you've taken blood samples - they're thinner than the electrolyte goo you're talking about. This stuff is not magically sticky in a picture and later capable of gymnastics in turbulence.
Do you know the consistency of this material over all temperature ranges? If so, how do you know? Also, blood is not terribly viscous and it gets all over everything. Are you saying this stuff is like blood?
Quoting Braybuddy (Reply 4): Murphy's Law. And aviation probably supplies one of the best (or worst) examples of same with the KLM/Pan Am collision at Tenerife in 1977: a bomb had exploded earlier at Las Palmas and the aircraft were diverted to Tenerife
Yup. Just about every major aviation disaster in history has occurred because of an unlikely chain of events all coinciding (leaving aside intentional sabotage).
Quoting liftsifter (Reply 2): Has John Leahy made a comment at all about the grounding and how it may affect the A350 program?
Even Mr. Leahy is smart enough to know to keep his mouth shut.
Anyway, it is far too early in the investigation to determine whether Airbus will actually need to make changes to the design of the A350, but you can rest assured that some people at TLS are watching these proceedings with great interest. And you can rest assured that none of them are gloating about it, because they know that if they are not careful, their new A350 might be next.
AirlineCritic From Finland, joined Mar 2009, 611 posts, RR: 1 Reply 7, posted (3 months 3 weeks 1 day 11 hours ago) and read 32412 times:
First, I'd like to thank once again CM, tdscanuck, rcair1 and others for informative posts. I would also like to welcome b2319 to a.net, your post certainly got me thinking about containment and relief valves as far more complex beasts than I had thought before. Thanks.
Second, I have a plea that this thread would not descent into political speculation or accusing NSTB or FAA of misbehaviour. They are one of the most respected organizations in the world in this area, and it would be, IMO, unthinkable that they would be misbehaving any way. They are the true experts. They have all the information that we do not have here in a.net. Exact state of containment systems and other equipment in the bays, for instance. If they say they need to ground the plane, they have a reason to do so. Even if it is just not being certain that no other damage occurs in some (perhaps obscure) other scenario than the one played out in the two incidents. Let them do their work.
And now to the topic of my post. I'm trying to understand different scenarios for lifting the grounding.
Scenario 1: Operational changes
ETOPS limitations, in-the-ground inspections, lower thresholds for diversion, perhaps some battery usage/charging changes in flight. If these procedures would be sufficient, the grounding could have been over in days. I can only conclude that either these procedures are insufficient, or that the NTSB does not understand the events well enough to allow the grounding to be lifted yet. Obviously, the root causes need to be found.
Scenario 2: Battery manufacturing quality
A problem is discovered in battery batches and/or manufacturing process, the issue is fixed and the planes start to fly again. If this was the solution, we could see the end of the grounding in weeks, particularly if defective batteries can be found by testing.
I think this is somewhat unlikely as the only fix, as I suspect the NTSB wants to understand how well the containment works in the eventual cases that even with high-quality batteries, there can be a thermal runway in one of them some day.
Scenario 3: Battery charging systems
Or perhaps these systems misbehaved in some way. A fix to them would be an engineering (and re-certification) process. In the best case this would take a few months, in the worst case more. I remember that the battery system manufacturer took seven years to design the current batteries. In my opinion, that is a very long time, and changing a component should be possible in months.
Charging system issues is a possible root cause, but it is looking a bit unlikely perhaps, if the early reports are true that the batteries were not overcharged. That being said, if the per-cell history of events burned down with the batteries, how would we know?
Scenario 4: Containment structures
It is probably not sufficient to fix the containment structures, but if a battery manufacturing fault is found, fixed, and the containment is enhanced to make the NTSB/FAA confident that it works in all cases, then the plane cloud clearly fly.
It is difficult to estimate how long this would take. A steel plate "shower curtain" would be very easy to add. Certification, analysis that it works in all cases would probably take longer. I'd say months.
A more significant modification, such as fluid venting out of the aircraft or even enlarging or moving the battery containment structure could take much longer. Half a year for venting out, years for moving the structure or making the EE bay larger to fit the new containment structure. FWIW, I think the shower curtain is probably going to be sufficient.
Scenario 5: Electrical system
Or maybe there is some issue with the electrical system that is causing trouble for the batteries. If this is the case, it would be very difficult and time-consuming to understand and fix the issues. But as an engineer, I find it difficult to believe this to be the case. Surely the design has voltage and current regulators that isolate the quality of the aircraft electricity from the quality of the electricity fed to the batteries.
But if they need to do something with the electrical system, it could take years. Adding a more high-quality regulation circuitry could be easy, however, maybe only months.
Conclusions
I think the issues are somewhere in categories 2 through 4. If a battery or charging system fault can be identified and a slightly enhanced containment put into place, the plane should fly in 4-6 months, if not sooner, at least as a temporary measure for current frames. And a more intelligent new containment adopted for future frames.
But it is also possible that once the events are understood, the current containment system is deemed adequate (as tdscanuck and CM believed early on in this thread). Then the critical time factor is understanding why the batteries failed, and I'd predict that to take some number of months anyway.
In the other extreme, it is also possible that the containment system needs a significant change. If no intermediate solution can be found, this could drag on for over a year. (Interestingly, according to Wikipedia, A350 should enter service mid 2014. If the worst comes to worst, we could see the 350 fly commercially before the 787 is back in the air. But I do not believe this to happen.)
Finally, I should add that none of this is rocket science. Batteries and charging systems are well understood. And the energy levels for containment are still... small, when you consider the size and energy content of the device. It is some number of times bigger than a car battery, not a nuclear bomb. Boeing engineers know how to enhance it, if it needs enhancing.
sweair From Sweden, joined Nov 2011, 1548 posts, RR: 0 Reply 8, posted (3 months 3 weeks 1 day 10 hours ago) and read 32289 times:
Just maybe we will have to accept that lion batteries will catch fire, on any airplane that uses them. It will be up to the containment to be able to handle any fire. Or just ban the use of lion in air craft all together. Someone needs to develop a JET-A fueled fuel cell quickly..
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 9, posted (3 months 3 weeks 1 day 7 hours ago) and read 30880 times:
Looking at the Tesla Roadster electric car for example, I find it interesting that the individual cells are so small in their design, yet they still use an active cooling and heating system to control the individual battery packs. Even the space between each cell seems much larger in relation to the cell size, than in the Boeing solution:
CALTECH From Poland, joined May 2007, 1575 posts, RR: 23 Reply 10, posted (3 months 3 weeks 1 day 5 hours ago) and read 29935 times:
Quoting B2319 (Reply 260):
I joined a.net because, in part 3 of this thread, someone said the electrolyte "wasn't a liquid, it was a paste". What an absolutely ill-informed post if there ever was one. Anyway, the physical properties of the material to be vented will play a vital part of the safe handling of the release. Some examples of physical properties are density, viscosity, possibly solids content and so on.
How totally incorrect and ill informed the above post is. With out revealing too much information, the paste statement was relayed to us by the manufacturers, you can figure that out for yourself if you'd like, not just a statement put out there by a anet member. But if someone knows more than Boeing and Thales, be my guest, go ahead and post your information. This is why folks are bailing on this thread.
b2319 From China, joined Jan 2013, 75 posts, RR: 0 Reply 11, posted (3 months 3 weeks 1 day 5 hours ago) and read 29636 times:
Quoting CALTECH (Reply 11): How totally incorrect and ill informed the above post is. With out revealing too much information, the paste statement was relayed to us by the manufacturers, you can figure that out for yourself if you'd like, not just a statement put out there by a anet member. But if someone knows more than Boeing and Thales, be my guest, go ahead and post your information. This is why folks are bailing on this thread.
I'm bailing too. You can pick up a copy of any physical chemistry textbook and try and understand my point. (I studied using Atkins, though there were others). The scientific terms for the three phases are solids, liquids and gases. Sometimes vapours and gases are interchangable, in some contexts.
From memory, the post was a claim that a paste was somewhat not a liquid or didn't posses a liquid component. In any case, there weren't any links supplied for me to consider the original source.
If you've the ability to determine that my criticism of scientifically-incorrect statements, independent of the source, albeit non-referenced, originated with yourself, well, that's impressive.
My GBP 15.40 experiment with a.net, has been exactly that- an experiment.
I'm bailing from both the thread, and the forum, and have no plans to contribute, nor lurk, again.
art From Lebanon, joined Feb 2005, 2937 posts, RR: 0 Reply 12, posted (3 months 3 weeks 1 day 5 hours ago) and read 29551 times:
Assuming (a) the cause of the overheating problem were identified (b) a fix had been designed, built and tested to a level where it would be acceptable to FAA (c) a fix for the containment issue had been designed, built and tested to a level where it would be acceptable to FAA, how long would it take the FAA to certify the aircraft as being safe again?
Once the aircraft were certified as safe, how long would it take to put the revised components into production and start installing them on the 787's delivered so far?
Would it be a few weeks between a solution to the problems being found and installation starting? Several (2/3/4) months?
Anyone have any idea how long the aicraft delivered will remain on the ground after a remedy is devised and approved?
CALTECH From Poland, joined May 2007, 1575 posts, RR: 23 Reply 13, posted (3 months 3 weeks 1 day 4 hours ago) and read 29108 times:
Quoting b2319 (Reply 12): I'm bailing too. You can pick up a copy of any physical chemistry textbook and try and understand my point. (I studied using Atkins, though there were others). The scientific terms for the three phases are solids, liquids and gases. Sometimes vapours and gases are interchangable, in some contexts.
So what you know is learned from a book. Interesting.
Quoting b2319 (Reply 12): From memory, the post was a claim that a paste was somewhat not a liquid or didn't posses a liquid component. In any case, there weren't any links supplied for me to consider the original source.
The memory point is incorrect and way off the mark. No where was it stated that it was not a liquid or didn't posess a liquid component, that has been inserted from a fallible memory. There were no links, it is what has been said by those who work with the batteries. Boeing is where the info comes from. Again, if you have info that shows Boeing has it wrong, please by all means please post it.
Quoting b2319 (Reply 12): If you've the ability to determine that my criticism of scientifically-incorrect statements, independent of the source, albeit non-referenced, originated with yourself, well, that's impressive.
Think It was my post that first brought up that the electrolyte is more of a paste than a liquid such as those found in lead acid batteries. A incorrect post #260 was made in the last thread #5, that was impressive, ' I joined a.net because, in part 3 of this thread, someone said the electrolyte "wasn't a liquid, it was a paste". What an absolutely ill-informed post if there ever was one. '
So excuse me if there is a issue with your "absolutely ill-informed post."
A fuel cell is a bit kinder to the environment than the APU as that is a small jet turbine itself. A fuel cell can use multiple fuels and create less pollution and noise. Maybe the cost and the heat is a problem?
flyglobal From Germany, joined Mar 2008, 502 posts, RR: 3 Reply 16, posted (3 months 3 weeks 1 day 3 hours ago) and read 28351 times:
Quoting seahawk (Reply 10): Looking at the Tesla Roadster electric car for example, I find it interesting that the individual cells are so small in their design, yet they still use an active cooling and heating system to control the individual battery packs. Even the space between each cell seems much larger in relation to the cell size, than in the Boeing solution:
And so will be other LI Car battery systems, like the Chevy Volt and newer Toyota's. Automotive use requires you to have your batteries at Winter in Canada and Russia (-40°C) and also at 100°C at least for heat (Death Valley, India, to name some location).
This requires heating devices and also ventilation and cooling ducts for the batteries.
For Air Planes the design requirements are different - less environmental temperature span at the battery location.
In one of the earlier threads I mentioned that I know that for Chevy it took rather 1/3rd effort for the Cell development and selection its self, 1/3rd for the packaging of the cells and 1/3rd for Power electrics and especially micro controls, software and data calibration.
For Automotive all is about warranty offer. A Chevy, a Toyota and probably as well the Tesla will only charge and discharge between 20 and 80% of capacity, depending on environment etc., charge and discharge is controlled depending on various parameters. Remember the Chevy Volt which caught fire about 2 weeks after a crash test.
A containment and updated procedures after accuidents have been the results.
My gut feel is that we will see something like this as a solution for the Dreamliner:
1) A specific fire and smoke monitoring system, as well as additional temp sensors (probably incl. a camera will be installed)
2) Software, and data cal regarding charging and discharging strategies will be updated in direction of 'more conservative)
3) A regular Battery exchange cycle will be established (like a bottle deposit and return system in Europe)
4) Boeing in the meantime will work on an update of the battery system with a different less risky battery system and get this extensively tested and certified (maybe in 2 years from now) and also will develop a PIP for existing planes for that.
This is what my crystal ball sees coming down the road (air).
DocLightning From United States of America, joined Nov 2005, 16808 posts, RR: 57 Reply 17, posted (3 months 3 weeks 1 day 3 hours ago) and read 27884 times:
Quoting sweair (Reply 19):
A fuel cell is a bit kinder to the environment than the APU as that is a small jet turbine itself. A fuel cell can use multiple fuels and create less pollution and noise. Maybe the cost and the heat is a problem?
1) They are still a new and unproven technology.
2) They run at 400-800°C, which brings up a whole array of thermal containment issues for certification.
3) They would have to crack the fuel for hydrogen and then combine it with oxygen, leaving us to do what with the carbon?
I wont have to be hydrogen, it can be jet fuel or methanol or any other hydrocarbon source for a fuel cell. Airbus and Boeing are both researching fuel cells. One day we could do away with the apu and batteries. Its sadly no option on the 787.
But to be an optimist, maybe this incident will lead to greater efforts to make the fuel cell a viable option for commercial aviation in the future.
DocLightning From United States of America, joined Nov 2005, 16808 posts, RR: 57 Reply 20, posted (3 months 3 weeks 1 day 1 hour ago) and read 26666 times:
Quoting LN-KGL (Reply 21): Plasma and hydrogen on a plane to me says: This is even more dangerous than Lithium-ion battery - dare I mention STS-51 Challenger.
I think fuel cells on planes are an inevitability. I just am very doubtful that it will be one of the earlier applications. I think we'll see vast batteries of fuel cells powering ships before one flies aboard an airliner.
sweair From Sweden, joined Nov 2011, 1548 posts, RR: 0 Reply 21, posted (3 months 3 weeks 1 day 1 hour ago) and read 26614 times:
The small consumer fuel cells are fueled with methanol, quite expensive but people like them as they work 24/7 compared to solar power on boats etc Almost no noise as well.
They do create waste heat though. Fuel cells for vehicles seem to be towards hydrogen.
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 23, posted (3 months 3 weeks 1 day ago) and read 26114 times:
Quoting PC12Fan (Reply 24): Like they did after two events that could have been catastrophic?? No, the FAA acts as they always have - reactive.
Well, if that is your definition of reactive, then no new airplane or technology would ever fly. There is a "tipping point" at which one must act. Waiting too long would be reactive. Acting too early would just kill all innovation. Acting at the tipping point, before something calamitous happens, is prudent and proactive (in that they don't wait for an actual crash before they act).
pliersinsight From United States of America, joined May 2008, 446 posts, RR: 0 Reply 24, posted (3 months 3 weeks 1 day ago) and read 26058 times:
Quting flyglobal: "And so will be other LI Car battery systems, like the Chevy Volt and newer Toyota's. Automotive use requires you to have your batteries at Winter in Canada and Russia (-40°C) and also at 100°C at least for heat (Death Valley, India, to name some location)."
Are you taking battery compartment temps or air temp. I'm not so sure the air temperature reaches 100C (212F) in Death Valley. I've never been to India.....
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 25, posted (3 months 3 weeks 22 hours ago) and read 25508 times:
Quoting Braybuddy (Reply 4): Quoting RottenRay (Reply 1):
And, frankly, positing a battery meltdown followed by severe turbulence is something best left to Hollywood.
Murphy's Law.
Fortunately for all of us, airplane's aren't designed to Murphy's Law...otherwise they'd never fly. Murphy's Law does get applied to individual components...you have to be handle an single failure, regardless of probability. But if you play that game with compound failure you can't ever certify. So they regulators establish acceptable risks of a catastrophic event due to multiple causes and you work backwards from there to what's acceptable probabilities for the contributing events. The probability of a battery meltdown combined with turbulence on the same flight is going to be very low...probably not 1 in a billion low, but that's OK because battery meltdown plus turbulence isn't enough to be catastrophic. You'd need at least two other failures (probably four).
Quoting AirlineCritic (Reply 7): A more significant modification, such as fluid venting out of the aircraft or even enlarging or moving the battery containment structure could take much longer. Half a year for venting out, years for moving the structure or making the EE bay larger to fit the new containment structure.
They're not going to make the EE bay larger, nor would they need to. There's enough room in there to put a solid steel box with 1" walls, no problem, which would be gross overkill on containment. I think people are also underestimating the speed with which the OEM's and regulators can move when something really is their top priority and they put "all" their resources on it. Boeing did a much more substantial redesign of the power system, including designing, building, and installing new hardware and software, after the ZA002 event and that only took about 6 months.
Quoting sweair (Reply 8): Just maybe we will have to accept that lion batteries will catch fire, on any airplane that uses them.
No maybe about it...even if you design a battery that will never catch fire, you'll still have to design it to survive in case it does.
Quoting art (Reply 12):
Assuming (a) the cause of the overheating problem were identified (b) a fix had been designed, built and tested to a level where it would be acceptable to FAA (c) a fix for the containment issue had been designed, built and tested to a level where it would be acceptable to FAA, how long would it take the FAA to certify the aircraft as being safe again?
Days. Normally you develop the certification plan ahead of, or in parallel with, the design/build/testing. That way, as soon as you have the result, you sign the last line on the paperwork and you're done.
Quoting art (Reply 12): Once the aircraft were certified as safe, how long would it take to put the revised components into production and start installing them on the 787's delivered so far?
Weeks. You need to inject the change back into the production system at the point it makes sense (probably at the partners that stuff the sections containing the EE bays). You would rework all airplanes downstream of that in final assembly, or after assembly on the flightline.
Quoting sweair (Reply 16): A fuel cell is a bit kinder to the environment than the APU as that is a small jet turbine itself. A fuel cell can use multiple fuels and create less pollution and noise. Maybe the cost and the heat is a problem?
Multiple fuels aren't much use in this particular application, since you have an ample supply of a perfectly good fuel (Jet-A) and nobody wants to design/build/test another fuel system when you don't need one. Boeing has already tested fuel cell's for aviation use as part of the ecoDemonstrator program last year.
Quoting flyglobal (Reply 17): 1) A specific fire and smoke monitoring system, as well as additional temp sensors (probably incl. a camera will be installed)
I'll eat my hat if they put in a camera.
Quoting PC12Fan (Reply 23): Like they did after two events that could have been catastrophic??
I'm still waiting for somebody to explain a foreseeable chain of events that ends in catastrophe, given how the airplane is designed. FAA/NTSB must have one in mind, given their statement, but they're not sharing. Lots of people have opined that the plane was "lucky to not have crashed" or words to that effect, yet I haven't seen one example of a foreseeable catastrophic failure chain.
Also, replying to a comment in Part 5 that I didn't get to before it was locked regarding LRU succeptability to liquid contamination in the aft EE bay (the accusation was that I'd never held an LRU)...the design criteria for the aft EE bay are quite different due to the presence of the liquid cooling system and high power density back there...the LRU's don't look like normal federated LRU "black boxes". Even in the forward bay, the liquid tolerance of LRU's is quite a bit higher than most people would think...even in normal operation, you've got no way to make sure that someone doesn't spill a couple of gallons of liquid (likely cleaner) on the main deck that drools down into bilge and EE bays.
alfablue From Spain, joined Jan 2013, 41 posts, RR: 11 Reply 27, posted (3 months 3 weeks 22 hours ago) and read 25952 times:
Quoting tdscanuck (Reply 25): The probability of a battery meltdown combined with turbulence on the same flight is going to be very low
Another comment which barely reflects facts or knowledge. The 787 is (or was) ETOPS certified and those Transatlantic tracks are not fixed. They change every day to avoid headwinds or make use of jet streams (west wind drift) and those turbulence associated to jet streams are hard to avoid on trans oceanic crossings. I hardly ever had a crossing where I didn't encounter turbulence. Even flight plan providers like Lufthansa's LIDO use live data to calculate routes with maximum tailwind (or minimum headwind) even if not straight - downside is that those are often along jet streams and turbulence.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 29, posted (3 months 3 weeks 19 hours ago) and read 24383 times:
Quoting alfablue (Reply 27): Quoting tdscanuck (Reply 25):
The probability of a battery meltdown combined with turbulence on the same flight is going to be very low
Another comment which barely reflects facts or knowledge.
The comment I was replying to specifically referenced severe turbulence. I didn't repeat "severe" because I was typing quickly (shame on me) and was obviously replying to a direct quote:
Quoting Braybuddy (Reply 4): Quoting RottenRay (Reply 1):
And, frankly, positing a battery meltdown followed by severe turbulence is something best left to Hollywood.
Murphy's Law.
The context we're talking about is bouncing electrolyte around the EE bay. Since the battery is at the bottom, it's only possible to get the electrolyte to go up any significant distance in any quantity if you get up to near 1g turbulence, which is consistent with the technical definition of severe turbulence.
Quoting alfablue (Reply 27): The 787 is (or was) ETOPS certified and those Transatlantic tracks are not fixed. They change every day to avoid headwinds or make use of jet streams (west wind drift) and those turbulence associated to jet streams are hard to avoid on trans oceanic crossings. I hardly ever had a crossing where I didn't encounter turbulence.
Exactly. Airlines spend extraordinary efforts to avoid even moderate turbulence...the probability of encounting servere turbulence, by itself, is already small. Compounding that with a battery fire, which is also small (though not nearly as small at the moment as anyone would like) gets you to a *very* small number. Then pile on the fact that you actually need the "bounced" eletrolyte to actually fail multiple other components before you threaten the aircraft, you'd out into very very small probabilities. Maybe not 1 in a billion, which is what the FAA requires, but they've got to be close.
thunderboltdrgn From Sweden, joined Jan 2012, 124 posts, RR: 0 Reply 30, posted (3 months 3 weeks 18 hours ago) and read 23585 times:
Quoting RottenRay (Reply 1): Really and truly, these situations just don't line up like that. Outside of Hollywood, that is.
Actually it did happened two weeks ago when a commuter train crashed into a house.
Caused by a chain of events/factors so unlikely that they together actually made the impossible possible.
PHX787 From Japan, joined Mar 2012, 4946 posts, RR: 15 Reply 31, posted (3 months 3 weeks 17 hours ago) and read 23239 times:
http://www.japantoday.com/category/n...l-unable-to-find-cause-of-787-fire
This is nuts. Wouldn't they be better off with a replacement source of electricity that can readily be approved until they figure this crap out, instead of just dragging this on?
Yesterday's JL 7 was op'd by a 77W. I'm sure it was quite the sight in BOS.
Has NH and JL been shouldered the burden of reimbursing stranded pax? Wouldn't the DOT make Boeing pay this?
Kaiarahi From Canada, joined Jul 2009, 2574 posts, RR: 24 Reply 32, posted (3 months 3 weeks 17 hours ago) and read 23218 times:
Quoting tdscanuck (Reply 29): Exactly. Airlines spend extraordinary efforts to avoid even moderate turbulence...the probability of encounting servere turbulence, by itself, is already small. Compounding that with a battery fire, which is also small (though not nearly as small at the moment as anyone would like) gets you to a *very* small number. Then pile on the fact that you actually need the "bounced" eletrolyte to actually fail multiple other components before you threaten the aircraft, you'd out into very very small probabilities. Maybe not 1 in a billion, which is what the FAA requires, but they've got to be close.
May I inject a small dose of reality. The probability of a thermal runaway, coupled with severe turbulence that somehow throws a paste electrolyte into systems that are designed to withstand cooling system liquids, and that causes multiple other systems to fail, is somewhat less likely than the probability that the flight crew will suffer simultaneous heart attacks (or that consumer electronic devices on board an aircraft will smoulder/vent/explode in flames - the FAA has 132 documented incidents just within its jurisdiction).
The reality is that the predominant cause of accidents is pilot error. Aircraft systems are generally far more robust than (most of) the people who fly them. Most design recommendations from safety boards are directed towards mitigating pilot error.
And I should add, this is coming from someone who has flown military aircraft in anger.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 33, posted (3 months 3 weeks 17 hours ago) and read 22944 times:
Quoting PHX787 (Reply 31): Has NH and JL been shouldered the burden of reimbursing stranded pax? Wouldn't the DOT make Boeing pay this?
Which stranded pax? Anyone disrupted in the first couple of days were long ago reaccommodated, and those on flights continuing to be cancelled are being reticketed.
packsonflight From Iceland, joined Jan 2010, 321 posts, RR: 0 Reply 34, posted (3 months 3 weeks 16 hours ago) and read 22911 times:
Quoting tdscanuck (Reply 29): The context we're talking about is bouncing electrolyte around the EE bay. Since the battery is at the bottom, it's only possible to get the electrolyte to go up any significant distance in any quantity if you get up to near 1g turbulence, which is consistent with the technical definition of severe turbulence.
Come on, you know better.
Every certification requirement, and that includes the special Li ion certification requirement, is issued for the whole certified flight envelope, including severe turbulence. If not, there would have to be operation limitation on the aircraft.
cornutt From United States of America, joined Jan 2013, 215 posts, RR: 1 Reply 35, posted (3 months 3 weeks 16 hours ago) and read 22740 times:
Quoting tdscanuck (Reply 25): Lots of people have opined that the plane was "lucky to not have crashed" or words to that effect, yet I haven't seen one example of a foreseeable catastrophic failure chain.
Hmm... I wonder if they have a concern about the external venting. Were that to become blocked early in a battery event, say by melted material, could it cause enough pressure buildup to burst the containment?
Quoting PHX787 (Reply 31): Has NH and JL been shouldered the burden of reimbursing stranded pax? Wouldn't the DOT make Boeing pay this?
I don't think the FAA or the DoT would have anything to do with it... it's a matter of the warranty terms between Boeing and the airlines.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 36, posted (3 months 3 weeks 16 hours ago) and read 22744 times:
Quoting PHX787 (Reply 31): Has NH and JL been shouldered the burden of reimbursing stranded pax?
Yes, for those that are stranded. Are there any left?
Quoting PHX787 (Reply 31): Wouldn't the DOT make Boeing pay this?
Generally not. Even if that were the policy (and it's not), DOT has zero jurisdiction on what happens with a Japanese carrier's reimbursement policy.
Quoting packsonflight (Reply 34): Every certification requirement, and that includes the special Li ion certification requirement, is issued for the whole certified flight envelope, including severe turbulence. If not, there would have to be operation limitation on the aircraft.
That's true for normal operation, not generally generally true of failures. There are quite a few failures (mostly in the flight controls) that will limit the operational envelope of the aircraft. The special conditions require that damage due to vented gas/fluid from a fried battery be a certainly likelyhood...if severe turbulence is required to get to that damage, the probability of severe turbulence would play into the probability calculation. It's somewhat similar to not having to assume that lightning strike probability is 1, even though you have to design for a lightning strike. Also, severe turbulence, by definition, implies brief periods of loss of control, which is *also* outside the operating envelope.
vivekman2006 From India, joined May 2006, 514 posts, RR: 3 Reply 37, posted (3 months 3 weeks 16 hours ago) and read 22687 times:
Quoting pliersinsight (Reply 24): Quting flyglobal: "And so will be other LI Car battery systems, like the Chevy Volt and newer Toyota's. Automotive use requires you to have your batteries at Winter in Canada and Russia (-40°C) and also at 100°C at least for heat (Death Valley, India, to name some location)."
Are you taking battery compartment temps or air temp. I'm not so sure the air temperature reaches 100C (212F) in Death Valley. I've never been to India.....
OMG No! Nowhere on this planet does the air temperature reach 100C (212F) Not even close!
100C is the temperature at which water boils and is absolutely un-survivable! The highest temperature ever recorded on Earth is 56.7C (134F) in Death Valley, CA
Sadly, I think that is likely. At least for a bit.
Quoting sweair (Reply 15): A fuel cell is a bit kinder to the environment than the APU as that is a small jet turbine itself. A fuel cell can use multiple fuels and create less pollution and noise. Maybe the cost and the heat is a problem?
Besides otherwise mentioned limitations, fuel cells are heavy for the power delivered, have a slow start time (APUs must *start* and immediately deliver the needed power), and as already noted are unproven. Aircraft are conservative.
Let's put it this way. Lithium batteries are standard in the world I live in. Other options haven't been discussed for years. Yet everyone is treating them as an unknown. (This is but a larger scale implementation that didn't go well.) While I think fuel cells are destined to go on aircraft eventually, that is a long ways away.
nycdave From United States of America, joined Aug 2010, 518 posts, RR: 1 Reply 39, posted (3 months 3 weeks 15 hours ago) and read 22286 times:
Have been fascinated and (sometimes) enlightened by these threads. Just hoping that in this latest iteration we can at least avoid the "it's a political conspiracy!" posts.
Look, having worked in government both on the political side (on Capitol Hill), and on the civil service side (in NYC), and in between, working in a regulator-heavy position at an i-bank, let me tell you: IT DOESN'T WORK THAT WAY.
The FAA, and especially the NTSB, are going to be even more stocked with civil servants than political appointees than the average agency. These are people who are there year in, year out, regardless of who's elected to what. These are the sort of people who, if the political folks DID want to pursue some industry-crushing conspiracy would be running to Huffington Post or Drudge Report with incriminating evidence.
Bureaucracies are built to be cautious, and are just as subject to fears of how a failure will make them look as anyone else. They can make mistakes, and people at key decision points can make different calls than we might when juggling several competing factors. But let's cut all this nonsense about "Oh, Obama is mad at Boeing", or "The Europeans are behind it!" and all that other junk... The FAA made the call that grounding 50 very high-profile planes until there's a clear answer about a scary (if not necessarily life-threatening) recurring flaw with a new technology was going to be safer, and less damaging to the airline industry, than letting them keep flying and just seeing what happened. Even if you, personally, wouldn't have made that call with the information we have available, you can't say there's not a solid case to be made for it.... rather than some malicious conspiracy!
KELPkid From United States of America, joined Nov 2005, 5929 posts, RR: 4 Reply 40, posted (3 months 3 weeks 14 hours ago) and read 22080 times:
Quoting nycdave (Reply 39): The FAA made the call that grounding 50 very high-profile planes until there's a clear answer about a scary (if not necessarily life-threatening) recurring flaw with a new technology was going to be safer, and less damaging to the airline industry, than letting them keep flying and just seeing what happened. Even if you, personally, wouldn't have made that call with the information we have available, you can't say there's not a solid case to be made for it.... rather than some malicious conspiracy!
I just hope that when all is said and done, if the FAA's calls of the sky falling proves to be baseless, then someone makes those heads go rolling
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 41, posted (3 months 3 weeks 14 hours ago) and read 22049 times:
Quoting cornutt (Reply 35): Hmm... I wonder if they have a concern about the external venting. Were that to become blocked early in a battery event, say by melted material, could it cause enough pressure buildup to burst the containment?
That's certainly a good option...it would be consistent with all the FAA/NTSB comments I can think of so far and explain their concerns. Without seeing the spec document, we don't know what the requirements were for the battery vents but, if the battery vented but not the way it was supposed to, that would probably screw up all the other potential systems effect analysis for things in the vicinity of the battery.
Quoting KELPkid (Reply 40): I just hope that when all is said and done, if the FAA's calls of the sky falling proves to be baseless, then someone makes those heads go rolling
I don't think it can ever be shown to be baseless...conservative, maybe, but it would be hard to argue they had *no* reason to be concerned. Unless there's a whole lot of hidden information that's being suppressed but with multiple investigating bodies and agencies that's basically impossible. If it does turn out to have been obviously over-conservative I feel bad for anybody at the FAA who gets yelled at...they had to make a call with very little data to work with. Somebody has to make a call, one way or the other, and they won't always be right.
packsonflight From Iceland, joined Jan 2010, 321 posts, RR: 0 Reply 42, posted (3 months 3 weeks 14 hours ago) and read 21920 times:
Quoting tdscanuck (Reply 36): The special conditions require that damage due to vented gas/fluid from a fried battery be a certainly likelyhood...if
As I understand this, the special condition say that battery fire should contained and not pose a danger to other system, and this goes for the whole flight envelope with no exceptions. Apparently FAA is not happy with the containment on those two occasions.
Quoting KELPkid (Reply 40): I just hope that when all is said and done, if the FAA's calls of the sky falling proves to be baseless, then someone makes those heads go rolling
I think they are simply doing their job. Without a credible explanation of why those two batteries went up in flames you really can not say they are not acting in good faith.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 44, posted (3 months 3 weeks 13 hours ago) and read 21815 times:
Quoting vivekman2006 (Reply 37): OMG No! Nowhere on this planet does the air temperature reach 100C (212F) Not even close!
Not in nature but in a Sauna you can go up to 120 deg C. Humidity is zero, though.
Quoting vivekman2006 (Reply 37): 100C is the temperature at which water boils and is absolutely un-survivable! The highest temperature ever recorded on Earth is 56.7C (134F) in Death Valley, CA
Aesma From France, joined Nov 2009, 4774 posts, RR: 9 Reply 45, posted (3 months 3 weeks 12 hours ago) and read 21585 times:
Quoting KELPkid (Reply 40): I just hope that when all is said and done, if the FAA's calls of the sky falling proves to be baseless, then someone makes those heads go rolling
You quote a post that you have not understood at all, apparently.
Quoting cornutt (Reply 35): Hmm... I wonder if they have a concern about the external venting. Were that to become blocked early in a battery event, say by melted material, could it cause enough pressure buildup to burst the containment?
You just made me think of something. You're talking about the venting of the battery itself, but what about the outflow valve ? If that gets blocked, then there is nowhere to go for the smoke except in the cabin/cockpit.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
cornutt From United States of America, joined Jan 2013, 215 posts, RR: 1 Reply 46, posted (3 months 3 weeks 12 hours ago) and read 21504 times:
Quoting Aesma (Reply 45):
You just made me think of something. You're talking about the venting of the battery itself, but what about the outflow valve ? If that gets blocked, then there is nowhere to go for the smoke except in the cabin/cockpit.
Interesting point. How much smoke would be generated, and how toxic would it be? Although if the outflow valve was completely blocked, I think the whole aircraft would quickly be in trouble with over-pressurization. I assume there are over-pressure relief valves, but I have no idea where in the aircraft they might be.
JoeCanuck From Canada, joined Dec 2005, 4993 posts, RR: 29 Reply 47, posted (3 months 3 weeks 11 hours ago) and read 21329 times:
Quoting packsonflight (Reply 42): Apparently FAA is not happy with the containment on those two occasions.
The FAA approved the containment...and for the most part, the containment did it's job; it prevented the spread of fire, significant damage from fire and significant damage from electrolyte. Obviously, some electrolyte did escape containment, and like with so many deficiencies in other aircraft, it was a scenario either never thought of or thought to be too unlikely to ever happen to be cause for concern.
To solve that particular problem, they build a more robust container...perhaps double or triple walled with expansion space and dedicated venting. That obviously doesn't solve the battery problems, but it would take care of the containment.
History is rife with aircraft which were globally certified and later found to have flaws which required redesign. In these cases, no person or aircraft was lost, damage was limited, the flawed parts were identified, removed and are being thoroughly tested.
The causes will be discovered and solutions offered. Perhaps an interim solution will be presented to get the fleet flying again, until a permanent modification is certified.
Quoting PC12Fan (Reply 22): Like they did after two events that could have been catastrophic?? No, the FAA acts as they always have - reactive.
Why would the FAA act on a system they certified when there was no fault? They aren't psychic...they can't know ahead of time of every possible failure and pre-emptively ground aircraft, ala Minority Report.
They are proactive in their certification processes. They take specific data about a particular plane, study how similar systems have failed in the past, apply past and present knowledge to potential future problems and eventually certify an aircraft.
Of course they are reactive after an accident...they can't react until they have something to react to, and since it is impossible to think of every possible failure scenario, sometimes lessons aren't learned until people die. In these cases, the certified containment worked well enough that all people and the planes survived.
When the 787 is re-certified, it will be an improved plane...but it is probable that there are potential problems yet to be discovered...and will have to be fixed in the future. I doubt there is an aircraft flying without a host of AD's on it...and every one a mandatory fix or modification.
rwessel From United States of America, joined Jan 2007, 1988 posts, RR: 2 Reply 48, posted (3 months 3 weeks 11 hours ago) and read 21319 times:
Quoting sweair (Reply 28): You would still need batteries even with a fuel cell/fuel cells?
If you had H2/O2 powered fuel cells, you'd need enough power to open the valves to the tanks, assuming the tanks were pressurized. You'd also need some regulation, but that can be done mostly mechanically.
You'd also be looking a reasonable lag before these came up to full power, which they won't do until the catalyst gets warm enough.
If you're running Jet-A and air into your fuel cell, you'll need to heat up the reformulator first, so you can decomposed the Jet-A, which will take both time and a fair bit of power.
A battery will supply power *right now*.
A fuel cell might be a reasonable alternative to an APU, but *not* the batteries.
ed:
Also, fuel cells don't produce all that much power (watts) for a given weight of fuel cell. They are useful because they can convert fuel into (electrical) energy (watt-seconds or Joules) with considerable efficiency, so the total mass of your fuel+fuel-cell system can be much, much lower than trying to same number of Joules out of a battery. But it will delivery those Joules much more slowly than a battery (IOW, fewer watts).
Batteries are much better for high, but relatively short, loads.
AngMoh From Singapore, joined Nov 2011, 319 posts, RR: 0 Reply 49, posted (3 months 3 weeks 11 hours ago) and read 21238 times:
Quoting pliersinsight (Reply 24): Quting flyglobal: "And so will be other LI Car battery systems, like the Chevy Volt and newer Toyota's. Automotive use requires you to have your batteries at Winter in Canada and Russia (-40°C) and also at 100°C at least for heat (Death Valley, India, to name some location)."
Are you taking battery compartment temps or air temp. I'm not so sure the air temperature reaches 100C (212F) in Death Valley. I've never been to India.....
Automotive specification for max temperature for components:
Cabin mounted components: max operating temp 85 deg C
Components mounted in engine bay: max operating temp 105 deg C
Components mounted on the engine: max operating temp 125 deg C
For most parts the minimum operating temperature is -40 deg C, but most cars are calibrated only for guaranteed starting at -30 deg C.
So lead acid batteries are mounted in the engine compartment and are rated to 105 deg C temp only (internally they can get a bit warmer) while Li-Ion batteries for hybrid and electrical cars are placed in separate compartments under the floor of the car and as such are only rated up to 85 deg C.
And talking about fuel cells - they are even further away. Fuel cells have not improved significantly over the last 20 years. I always hear it is the next big thing. But I can research in them seeing cut back. For example, a fuel cell car trial in Singapore was stopped with the hydrogen refilling stations being dismantled and replaced by a trial of electric cars. Same for RR stationary fuel cells (about 400kW) research - it was always promoted by the local researchers but now seems to have gone quiet while at least 3 labs (bunkers) for Li-Ion battery research have been built or are being built.
BTW an exploding Li-Ion battery at solar research lab of NUS was responsible for the quite spectacular flames last year: http://www.channelnewsasia.com/photo...gallery/gallery_20120810181310.htm
(the fire looked a lot worse than it was - the only thing which cought fire was the ventilation duct from the lab to the roof).
Unflug From Germany, joined Jan 2012, 187 posts, RR: 0 Reply 50, posted (3 months 3 weeks 11 hours ago) and read 21235 times:
Quoting vivekman2006 (Reply 37): OMG No! Nowhere on this planet does the air temperature reach 100C (212F) Not even close!100C is the temperature at which water boils and is absolutely un-survivable! The highest temperature ever recorded on Earth is 56.7C (134F) in Death Valley, CA
I don't think that air temperature is relevant in this case, we are talking about limits for car batteries. I am quite sure that the inside of a black car in Death Valley can easily reach 100C.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 51, posted (3 months 3 weeks 11 hours ago) and read 21214 times:
Quoting JoeCanuck (Reply 47): The FAA approved the containment...and for the most part, the containment did it's job; it prevented the spread of fire, significant damage from fire and significant damage from electrolyte. Obviously, some electrolyte did escape containment, and like with so many deficiencies in other aircraft, it was a scenario either never thought of or thought to be too unlikely to ever happen to be cause for concern.
Well, I would say the containment worked reasonably in the first incident, but failed in the second. Flammable liquids (or paste) must not escape the containment.
It is like the containment of any storage tank for flammable liquids. If the tank fails and burns and the material burns inside the containment, the safety design works. If the tank just releases the material and it escapes the containment, the safety design failed, even if the material never burned in that incident.
Just imagine having a type 2 incident (release of flammable liquids) followed by the ignition and fire of a type 1 incident and you got the potential risk that the FAA must consider. And from a pure technical point of view, each battery cell is one storage tank in this example, so a combination of both types of events seem possible as far as I can understand the problem.
flyglobal From Germany, joined Mar 2008, 502 posts, RR: 3 Reply 52, posted (3 months 3 weeks 10 hours ago) and read 21247 times:
Quoting pliersinsight (Reply 24): Are you taking battery compartment temps or air temp. I'm not so sure the air temperature reaches 100C (212F) in Death Valley. I've never been to India.....
To make thinks clear: we talk about a car which stays in the sun in 45°C for lets say 2-3 hs. It heats up quickly above the outside temperature. At least automotive has to design for 70-85°c. Its not only the batteries - also other car electronics have to work - engine management system, entertainment system under this conditions.
That's why batteries for car applications have extensive vent and even cooling ducts around the cells. I was surprised that the Dreamliner battery cells are just next to each other. I didn't expect it as extensive as in electric cars, but at least some!
Anyhow - hope they can get it wo work.
I am sure at Boeing - a Tesla/ Volt car like solution is part of an option discussed.
rotating14 From United States of America, joined Jan 2012, 374 posts, RR: 0 Reply 53, posted (3 months 3 weeks 10 hours ago) and read 21232 times:
I was watching the news ticker and saw something close to the link below. Looks like the investigation is shifting from the battery itself and now to the monitoring system behind the battery. Personally I think its too soon to be moving away from the batteries. I vouch for others when I say that the batteries on the -8 need room the breathe and cool down.
XT6Wagon From United States of America, joined Feb 2007, 3129 posts, RR: 4 Reply 54, posted (3 months 3 weeks 9 hours ago) and read 21176 times:
Quoting KELPkid (Reply 40): I just hope that when all is said and done, if the FAA's calls of the sky falling proves to be baseless, then someone makes those heads go rolling
To me the FAA has been reasonable. The grounding while largely fueled by Media Frenzy, does make cautionary sense until they get a handle on the common cause. (unlinked causes would be highly unlikely in events so close together, like two people in the same family winning the grand prize at two different lottos in the same week)
The NTSB on the other hand... Their statements blow my mind. To listen to them Boeing knowingly was selling firebombs to airlines and claiming they were fresh from the hands of God and all the perfection that implies. They seem to not understand basic things like the laws, regulations, special requirements, and in fact basic physics at times when they make statements about the 787.
Quoting seahawk (Reply 51): Flammable liquids (or paste) must not escape the containment.
Please point out where it says that... Others have time and again pointed out it DOESN'T say that in the special requirements.
More to the point, you really need to define Flammable. You can put fires out with diesel fuel. You can power rockets with aluminum and iron. As far as I know we have never seen any definition of how the electrolyte reacts. We don't know its self ignition temp. We don't know if it can be burned at lower temps in the presence of a flame. If it can be burned quickly if converted to a mist or particulate stream is also unstated.
For all we know the flames escaping the containment vessel were other substances in the box contained in quanity. I'm assuming it has a fair bit of various insulating materials, all which likely burn well below the tempature of the battery in thermal runaway.
Also ignored by many calling for 100% containment, lets look at a recent viral video. http://www.youtube.com/watch?v=ChCVfn9ePDc
you might note that there was NO combustion involved in this explosion. The tank reached a pressure at which it could not hold and then suffered complete failure. If you don't believe me, spend some research into boiler explosions. Many of the largest blasts in the 19th century outside of war were boiler explosions. Just a bit of water and heat would toss chunks of locomotives for miles.
So when you call for 100% containment you are asking for the intentional creation of a potential explosion. One in which many fairly vital electrical panels are located in relative close proximity. This would be thousands of times worse than a little burning electrolite getting sprayed onto the external metal covers. Which hasn't been shown to be possible much less probable during flight.
Quote: Japan's government stepped in to give Boeing Co's now-grounded 787 Dreamliner and its made-in-Japan technology a boost in 2008 by easing safety regulations, fast-tracking the rollout of the groundbreaking jet for Japan's biggest airlines, according to records and participants in the process.
Quote: There is no suggestion that easing regulatory standards contributed to the problems facing the Dreamliner, idled around the world after a string of malfunctions ranging from fuel leaks to battery meltdowns. There is also no evidence to suggest that continuing the mandate for more frequent manual inspections for new aircraft, including the Boeing 787, before 2008 would have helped catch signs of trouble earlier.
Difficult to see whether this will have any bearing on the duration of the grounding or not. Definitely not a favourable development for ANA and JAL though if the Japanese authorities feel they have to be more conservative than the FAA to cater to local public opinion.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 56, posted (3 months 3 weeks 8 hours ago) and read 20896 times:
Quoting XT6Wagon (Reply 54): So when you call for 100% containment you are asking for the intentional creation of a potential explosion. One in which many fairly vital electrical panels are located in relative close proximity. This would be thousands of times worse than a little burning electrolite getting sprayed onto the external metal covers. Which hasn't been shown to be possible much less probable during flight.
Please read my post correctly. I said flammable liquids, this does not mean 100% containment. I am fully aware that gases must be able to escape in an controlled manner, to avoid overpressure and possible damage from this. This is something I would consider standard safety design. Yet I think this failed in the second incident.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 57, posted (3 months 3 weeks 8 hours ago) and read 20826 times:
Quoting XT6Wagon (Reply 54): So when you call for 100% containment you are asking for the intentional creation of a potential explosion. One in which many fairly vital electrical panels are located in relative close proximity. This would be thousands of times worse than a little burning electrolite getting sprayed onto the external metal covers. Which hasn't been shown to be possible much less probable during flight.
Not if you can provide sufficient expansion for the solids, and an escape valve externally for the gases. The existing container was what you have described, although it does leak, but not in a controlled manner. Since it just depends on uncontrolled and unpredictable deformation of the lid, then there is no saying if fire and smoke can escape, or flammable liquids can spurt out. If it had not leaked, could it have exploded?
Have we had a final word yet on if flame escaped in the first incident.. I keep reading conflicting claims on that.
PITingres From United States of America, joined Dec 2007, 954 posts, RR: 12 Reply 58, posted (3 months 3 weeks 6 hours ago) and read 20181 times:
Quoting seahawk (Reply 56): I said flammable liquids, this does not mean 100% containment.
XT6Wagon's statement stands correct. There is no criteria for containment of liquids, flammable or not. The only criterion that matters is that the leakage not be able to hurt anything critical.
Even if you assume that the leaked electrolyte is flammable and burns, if there isn't much of it, it would not necessarily pose a hazard to the EE bay which must be designed to withstand a certain amount of damage.
Now, I'm not advocating that allowing the gunk to drip uncontained was a good idea. I rather think that the designers are wishing that they had added a drip tray or splash guard surrounding the primary containment. I'm just contradicting the notion that any electrolyte leakage is prohibited. It's the results that matter, not the leakage.
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 59, posted (3 months 3 weeks 5 hours ago) and read 20012 times:
Quoting Aesma (Reply 45): You just made me think of something. You're talking about the venting of the battery itself, but what about the outflow valve ? If that gets blocked, then there is nowhere to go for the smoke except in the cabin/cockpit.
The forward overboard vent valve while not as large as the aft outflow valve is still large enough that blocking it would be difficult and is not in a position for large quantities of viscous material to find its way out of the airplane through it. The drain valves that run along the bottom of the airplane are closed by pressure shortly after takeoff, so I'm guessing a dedicated "drip/vent" line would be required.
Kaiarahi From Canada, joined Jul 2009, 2574 posts, RR: 24 Reply 61, posted (3 months 3 weeks 4 hours ago) and read 19579 times:
Quoting tdscanuck (Reply 41): I don't think it can ever be shown to be baseless...conservative, maybe, but it would be hard to argue they had *no* reason to be concerned.
Which does make me wonder how they'll react when a consumer device lets go in the cabin with serious damage. Of the 132 incidents documented so far by the FAA, it was just dumb luck in at least a dozen cases that there weren't serious consequences. Will they ban all devices on flights? Require the installation of a containment compartment into which pax must place all devices?
mham001 From United States of America, joined Feb 2005, 3000 posts, RR: 3 Reply 63, posted (3 months 3 weeks 4 hours ago) and read 19484 times:
Quoting rotating14 (Reply 53): I vouch for others when I say that the batteries on the -8 need room the breathe and cool down.
I don't know about others but these batteries only get hot under heavy discharge/charge. The 787 batts don't see that much use by design. I do think however having the BMS in the same box is absurd. This would not have have happened were I in charge of that design.
PITingres From United States of America, joined Dec 2007, 954 posts, RR: 12 Reply 64, posted (3 months 3 weeks 3 hours ago) and read 19079 times:
Quoting mham001 (Reply 63): I do think however having the BMS in the same box is absurd. This would not have have happened were I in charge of that design.
Well, maybe. Trouble is that as soon as you take the management circuitry out of the box you have cabling and connectors to worry about, and they fail too. Plus it would be an added weight and expense. I'm sure that the engineering trade has to come down on the side of reliability even if other (non-battery) things fail, as opposed to preserving the BMS state if the battery poofs. Moving the BMS out of the box might be the right thing anyway, but I don't think it's quite the slam-dunk that you present it as. How about leaving it in the box and adding a little potting or thermal insulation around it?
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 67, posted (3 months 3 weeks 2 hours ago) and read 18636 times:
Excerpt from the Wall Street Journal today: "Shortly after the Federal Aviation Administration issued safety rules in 2007 for using lithium-ion batteries on Boeing Co.'s 787 Dreamliner jets, an industry standards-setting group called for stricter testing to prevent battery fires on aircraft.
Boeing and FAA officials decided that since design and testing of the plane was so far along, mandating the tougher standards would disrupt years of joint safety work and unfairly delay production of the cutting-edge Dreamliners, said people familiar with the details. "
Now they move on to looking at other parts of the electrical system, or to the design of the battery itself.
It does not mean they're at a dead end, as some others have suggested. It just means they appear to have ruled out the simplest potential cause: a faulty battery, or a "bad batch" of batteries.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
frmrCapCadet From United States of America, joined May 2008, 1501 posts, RR: 1 Reply 69, posted (3 months 3 weeks 2 hours ago) and read 18555 times:
There are reports coming out that that are clearing various parts and systems from fault, can one of the experts here tell us what this means. To an amateur the various reports look inconsistent.
This leaves the 'monitoring' system, but how could that cause a fault in a good battery and a good charging system? There are of course two different incidents and things may have failed in slightly different ways. EGADS! That real makes it hard.
Buffet: the airline business...has eaten up capital...like..no other (business)
Thank you, my specific post on this was deleted by the moderators.
Lithium Ion batteries are used all over complex industry sectors as part of Uninterrupted Power Supply (UPS) units, notably in my field submarines, with little or no significant defects. Indeed the main hazards are disposing of them safely at the end of a lifecycle. The battery monitoring systems are also very reliable and are usually supplied along with the battery by the manufacturer. These monitoring circuits relay information to the battery charging system, which may or may not be supplied by the battery OEM. In my experience the charging units supplied by the OEM are also very reliable, but there is evidence that non-OEM systems may not be so. Recent high profile laptop and car battery faults/recalls bear testament to this.
The question I ask therefore is who has supplied the charging equipment for the B787 batteries and did any failure studies of the charging equipment consider the effect on the battery itself?
If the Japanese investigation is found to be conclusive that the OEM battery is not at fault, then the investigation perhaps need to focus more toward somewhere else on the aircraft to identify the root cause.
SonomaFlyer From United States of America, joined Apr 2010, 1171 posts, RR: 0 Reply 72, posted (3 months 3 weeks 1 hour ago) and read 18086 times:
The articles seem to rule out the battery and charging system. I am assuming they rule out any material defect in the assembly of the battery?
If the battery was not defective and the charging system is not defective, we should see this investigation broaden. This is of course problematic because it means the grounding would continue and the other systems (which presumably includes the software associated with these systems) are complex and reviewing code for debugging purposes takes time.
rolfen From Germany, joined Jan 2006, 1764 posts, RR: 2 Reply 73, posted (3 months 3 weeks 1 hour ago) and read 18044 times:
Quoting frmrCapCadet (Reply 69):
There are reports coming out that that are clearing various parts and systems from fault, can one of the experts here tell us what this means. To an amateur the various reports look inconsistent.
I don't think any system can be "cleared" in the sense where it can be absolved from any responsibility. Electrical systems are complex and bugs can be hidden deep inside and appear randomly. It might also be a problem with a specific batch...
When working with complex systems you can never rule out a component before fully understading what happened!
It is, and if it turns out that the explanation is "statistical aberration," then it will take many hundreds of thousands of event-free flying hours to demonstrate that.
The failure to find a consistent cause is very disturbing and indicates that this grounding may be quite prolonged.
Kaiarahi From Canada, joined Jul 2009, 2574 posts, RR: 24 Reply 75, posted (3 months 3 weeks 1 hour ago) and read 17964 times:
Before everyone concludes that 2+2=22, what the NTSB actually said was that it found no obvious anomalies in the undamaged JL battery (i.e. the forward bay battery). The NTSB said in last Thursday's briefing that the failed (APU) battery showed evidence of a short circuit (hole caused by an electrode). There are photos on the NTSB website. They are still "deconstructing" the failed battery.
They have also found no significant anomalies in the charging unit made by Securaplane (that's the unit that took 7 years to design and develop - no one has said that the battery took 7 years).
So far, they've also said that the circuit boards for the battery monitoring system (apparently made by Kanto) were too degraded to provide useful information.
rheinwaldner From Switzerland, joined Jan 2008, 2061 posts, RR: 6 Reply 76, posted (3 months 3 weeks ago) and read 17588 times:
Quoting seahawk (Reply 9): yet they still use an active cooling and heating system to control the individual battery packs
Lipos don't like cold temperatures. They loose a lot of capacity. Thus the real RC nerds heat them to 40°C before flying in Winter. That's for sure the reason why Tesla heats in some cases their lipos...
The issue is that the 787 is not grounded because of things that happen generally. Generally you are correct. Generally the 787 would not have been grounded. If it'd have behaved generally...
I repeat that it is not rocket science to charge and treat lipos in a way that they never start burning. Especially in such a highly professional environment and error-prone application. The NTSB and the FAA are right in demanding that the cells never get heated up unsafely. Because it is possible to build a system like that. The point is that the existing design fails to meet that requirement and that the reason is unknown. Thats all.
ba319-131 From United Kingdom, joined Jan 2001, 8258 posts, RR: 56 Reply 79, posted (3 months 2 weeks 6 days 23 hours ago) and read 17196 times:
Well, if the batteries have found to be 'clear' for duty, this seems to fall back to the electrical system in general. Given the huge amount of electrical cabling etc in this plane, the grounding could well be a long drawn out process, something Boeing nor the airlines can really afford.
This is turning into a true nightmare for everybody linked in whatever way to the 787 program.
Thankfully both of my 787 intercontinental flights went without issue, however with the publicity this ground has been getting will certainly eat into the Dreamliners 'halo' effect.
I hope Airbus are watching this closely and learning as much as they can, the A350 can ill afford similar delays and problems.
scbriml From United Kingdom, joined Jul 2003, 11357 posts, RR: 50 Reply 80, posted (3 months 2 weeks 6 days 23 hours ago) and read 17204 times:
Quoting ComeAndGo (Reply 77): Virgin Atlantic did so a few years ago.
That was a short-term issue related to two specific brands of laptop - Dell and Apple had a massive battery recall in 2006 after several battery fires. The laptops weren't banned but customers were asked to remover the batteries before take-off and could only use the device if their seat had a power source.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 81, posted (3 months 2 weeks 6 days 23 hours ago) and read 17071 times:
According to the NTSB slide presentation each battery cell has a Rupture Valve. Where does the electrolyte go to if it escapes through that valve. And if the electrolyte is conductive does it not pose a problem for the exposed cell terminals on top of each battery cell?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 82, posted (3 months 2 weeks 6 days 23 hours ago) and read 17002 times:
Quoting packsonflight (Reply 42): As I understand this, the special condition say that battery fire should contained and not pose a danger to other system, and this goes for the whole flight envelope with no exceptions.
The "exception" is the "extremely remote" stipulation...the FAA didn't require 100% protection, as they do for any single failure, but allow a (very small) probability of multiple things lining up. I don't see why turbulence wouldn't enter into that fault tree, as they do with lightning.
Quoting beau222 (Reply 43): Does the 748 series use the same type of battery or batteries that the 787 is having issues with?
Different.
Quoting Aesma (Reply 45): You just made me think of something. You're talking about the venting of the battery itself, but what about the outflow valve ? If that gets blocked, then there is nowhere to go for the smoke except in the cabin/cockpit.
There's another outflow valve (forward bilge) and overpressure relief valves (just below the main deck floor). The outflow valves are also large...it would take an extremely big piece of debris to fully block them.
Quoting cornutt (Reply 46): Although if the outflow valve was completely blocked, I think the whole aircraft would quickly be in trouble with over-pressurization. I assume there are over-pressure relief valves, but I have no idea where in the aircraft they might be.
They're on the left side forward, I believe, just below the main deck floor.
Quoting seahawk (Reply 51): Well, I would say the containment worked reasonably in the first incident, but failed in the second. Flammable liquids (or paste) must not escape the containment.
That's *not* a requirement of the special condition. In fact, by the way the special condition is written, it's explicitly allowed.
Quoting seahawk (Reply 51): It is like the containment of any storage tank for flammable liquids. If the tank fails and burns and the material burns inside the containment, the safety design works. If the tank just releases the material and it escapes the containment, the safety design failed, even if the material never burned in that incident.
The object is to make sure any release is harmless. Normal flammability containment isn't pressure tight, it has to vent something or it needs to be built as a pressure vessel.
Quoting mham001 (Reply 63): I do think however having the BMS in the same box is absurd. This would not have have happened were I in charge of that design.
The farther you move the BMS from the battery, the more potential failure points you inject into the fault tree. Given the extremely tight requirements the FAA put on the BMS, integration with the battery was probably, by far, the most reliable available option. The fact that the BMS was destroyed in the fire isn't that significant, since once a thermal runaway begins the BMS can't do anything about it anyway, it's too late.
Quoting sankaps (Reply 67): Boeing and FAA officials decided that since design and testing of the plane was so far along, mandating the tougher standards would disrupt years of joint safety work and unfairly delay production of the cutting-edge Dreamliners, said people familiar with the details.
Before everybody freaks out, note that this is how virtually all certification is done. They freeze the certification basis at a point in time (usually when the OEM notifies the regulatory that they're pursuing a new or amended TC) and agree to hold it there for a fixed period (usually 5 years) so that the OEM's have some design stability. Changes in the interim are assessed against the certification basis and they only roll in new requirements if they believe there's a really compelling need to do so. In this case, the FAA had no reason to think the existing standards weren't tough enough.
asctty From United Kingdom, joined Dec 2008, 72 posts, RR: 0 Reply 83, posted (3 months 2 weeks 6 days 22 hours ago) and read 16941 times:
Quoting ComeAndGo (Reply 81): According to the NTSB slide presentation each battery cell has a Rupture Valve. Where does the electrolyte go to if it escapes through that valve. And if the electrolyte is conductive does it not pose a problem for the exposed cell terminals on top of each battery cell?
The point here is that that batteries are OK if the control system works. Who owns the control system? The battery manufacturer specifies safe parameters for it to be operated within, If is is connected to a system that does not maintain these parameters then failure may result.
In the general hierarchy of risk reduction; Eliminate, Reduce, Isolate or Contain, where released electrolyte ends up and containing it is way down the list as the likelihood of a release should be engineered out. Don't forget that if the Rupture Valve is activated then the battery is now useless in its function as a safety supply to the aircraft electrical system. Now that is really important is it not? It appears that the Japanese authorities have found no manufacturing reason for the batteries to fail. So where does the fault reside? Surely it must be upstream/downstream of the battery depending if it is on charge or load.
I have stated before that these batteries reside safely in many safety critical system UPS's with a very high reliability, else they would be approved for such applications.
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 85, posted (3 months 2 weeks 6 days 22 hours ago) and read 16619 times:
Quoting tdscanuck (Reply 82): Quoting Aesma (Reply 45):You just made me think of something. You're talking about the venting of the battery itself, but what about the outflow valve ? If that gets blocked, then there is nowhere to go for the smoke except in the cabin/cockpit.
There's another outflow valve (forward bilge) and overpressure relief valves (just below the main deck floor). The outflow valves are also large...it would take an extremely big piece of debris to fully block them.
Quoting cornutt (Reply 46): Although if the outflow valve was completely blocked, I think the whole aircraft would quickly be in trouble with over-pressurization. I assume there are over-pressure relief valves, but I have no idea where in the aircraft they might be.
They're on the left side forward, I believe, just below the main deck floor.
If there is smoke in the fwd equipment area the fwd vent valve opens to clear the smoke overbd. It is a several inch hole in the airplane and it would be impossible for a glob of goo to find its way there let along block it. That's the valve with the black stuff in the ANA photo. The fwd outflow valve is bigger but generally almost closed during normal flight to pressurize the airplane. The bilge (water, goo whatever) goes out the drain valves which run along the keel beam at the bottom of the fuselage and are only open below 2+/- psi--so through out most of the flight they are closed--these could be blocked but that's not a big deal. For the positive pressure (over pressure) relief valves to open you'd have pressurize the airplane above its max limit which would mean both outflow valves (fwd & aft) would have to be closed and the fwd vent valve would have to be closed.
asctty From United Kingdom, joined Dec 2008, 72 posts, RR: 0 Reply 86, posted (3 months 2 weeks 6 days 22 hours ago) and read 16485 times:
Quoting 7BOEING7 (Reply 85): If there is smoke in the fwd equipment area the fwd vent valve opens to clear the smoke overbd. It is a several inch hole in the airplane and it would be impossible for a glob of goo to find its way there let along block it. That's the valve with the black stuff in the ANA photo. The fwd outflow valve is bigger but generally almost closed during normal flight to pressurize the airplane. The bilge (water, goo whatever) goes out the drain valves which run along the keel beam at the bottom of the fuselage and are only open below 2+/- psi--so through out most of the flight they are closed--these could be blocked but that's not a big deal. For the positive pressure (over pressure) relief valves to open you'd have pressurize the airplane above its max limit which would mean both outflow valves (fwd & aft) would have to be closed and the fwd vent valve would have to be closed
This is locking the door after the horse has bolted in safety terms as it will not prevent the battery overhating in the first place. A very complex suggestion as to how to deal with a battery that has potentially not been operated correctly thereby presenting a hazard to the aircraft. What if the battery was called upon to supply emergency power and permit safe landing of the aircraft?
Please reassure me this is not the normal hazard assessment approach in the airline industry?
michiganatc From United States of America, joined Nov 2008, 133 posts, RR: 0 Reply 87, posted (3 months 2 weeks 6 days 21 hours ago) and read 16455 times:
Forgive me if this was already talked about, I haven't had a chance to read through the 750+ posts
With the 787's all grounded, what airports did United's end up at? I'm hoping to see 1 or 2 at the United hangars next week.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 88, posted (3 months 2 weeks 6 days 21 hours ago) and read 16343 times:
Quoting michiganatc (Reply 87): With the 787's all grounded, what airports did United's end up at?
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 89, posted (3 months 2 weeks 6 days 20 hours ago) and read 16049 times:
Quoting asctty (Reply 86):
This is locking the door after the horse has bolted in safety terms as it will not prevent the battery overhating in the first place. A very complex suggestion as to how to deal with a battery that has potentially not been operated correctly thereby presenting a hazard to the aircraft. What if the battery was called upon to supply emergency power and permit safe landing of the aircraft?
Please reassure me this is not the normal hazard assessment approach in the airline industry?
All I was describing was the present way all the various "holes" in the airplane operate and the fact that the battery spreading goo around probably wouldn't block any of them or cause an overpressure event. It wasn't a battery design safety discussion.
justloveplanes From United States of America, joined Jul 2004, 871 posts, RR: 1 Reply 90, posted (3 months 2 weeks 6 days 20 hours ago) and read 16045 times:
Quoting francoflier (Reply 84): Let's not forget that Li-ion batteries have already downed an aircraft once.
If you are referring to the UPS 747, I think that was an entire pallet of Li Ion batteries. A huge amount of stored energy and a potential fireball. The ANA flight by comparison burned through the main on board battery completely, in flight, with no ill effects save for some sludge in the forward bay and smell.
BTW, If the containment had been "a little bit" better to start with, I don't think any of this grounding would have happened. Two failed components. This would be treated as a reliability issue and not a hazard, there is only so much energy in these things and you can design safe containment without any rocket science. There are much more stringent containment solutions used in much more hazardous environments (refineries, oil rigs and other, explosive, high heat and high vibration environments) that are in widespread use. This is not a problem without a ready solution, lots of proven know how for this type thing.
I believe the NTSB, JAA and others should approach this from a two step process:
Update the containment (straightforward, maybe a bit time consuming, but straightforward and predictable)
Re-examine the problem from a loss of system redundancy point of view for flight safety vice a flight hazard and then conclude grounding or AD.
rwessel From United States of America, joined Jan 2007, 1988 posts, RR: 2 Reply 91, posted (3 months 2 weeks 6 days 20 hours ago) and read 15946 times:
Quoting ComeAndGo (Reply 81): According to the NTSB slide presentation each battery cell has a Rupture Valve. Where does the electrolyte go to if it escapes through that valve.
Into the empty space in the battery case. And if enough boils out of the cells, obviously out the battery case vents and onto the floor of the EE bay. The scope of the latter may be one of the issues the FAA and NTSB are having.
Quoting ComeAndGo (Reply 81): And if the electrolyte is conductive does it not pose a problem for the exposed cell terminals on top of each battery cell?
Doesn't matter, the battery is dead/dying/self-destructing at that point anyway. The rupture values are there to prevent a pressure buildup that would lead to an explosive rupture.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 92, posted (3 months 2 weeks 6 days 20 hours ago) and read 15960 times:
Quoting JoeCanuck (Reply 47): The FAA approved the containment...and for the most part, the containment did it's job; it prevented the spread of fire, significant damage from fire and significant damage from electrolyte. Obviously, some electrolyte did escape containment, and like with so many deficiencies in other aircraft, it was a scenario either never thought of or thought to be too unlikely to ever happen to be cause for concern.To solve that particular problem, they build a more robust container...perhaps double or triple walled with expansion space and dedicated venting. That obviously doesn't solve the battery problems, but it would take care of the containment.
That's one problem.
According to the FAA "The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes."
However, there is no controlled means of releasing pressure in the existing design. The case is sealed, until pressure forces it to deform, allowing flammable material to be released. It allows heat damage to occur to surrounding equipment, so the case is not protecting the environment adequately either, in respect to the heat generated by a thermal runaway.
The enhanced case is obviously the answer, but what would this require in respect of design, manufacturing, testing and certification? How long would this process take? Would the FAA keep the 787 grounded till this whole process is complete.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 93, posted (3 months 2 weeks 6 days 20 hours ago) and read 15915 times:
Idle question: Other than just looking at the photo of the EE bay from the JAL plane, has there been any indication what other than the battery pack was damaged, and how long it would take to repair the ancillary damage the plane sustained?
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 94, posted (3 months 2 weeks 6 days 20 hours ago) and read 15776 times:
Another question. Wouldn't Boeing have had to do a battery failure containment test during certification. Given the design of the container, I would assume it would have behaved pretty much the same then as it did in the recent events. Would it not have had flammable electrolyte leaking out in those tests, and have generated the same amount of heat. Why would that have been acceptable then, but not now?
Stitch From United States of America, joined Jul 2005, 26682 posts, RR: 83 Reply 95, posted (3 months 2 weeks 6 days 19 hours ago) and read 15796 times:
Quoting RickNRoll (Reply 94): Another question. Wouldn't Boeing have had to do a battery failure containment test during certification. Given the design of the container, I would assume it would have behaved pretty much the same then as it did in the recent events. Would it not have had flammable electrolyte leaking out in those tests, and have generated the same amount of heat. Why would that have been acceptable then, but not now?
BECAUSE THE SPECIAL CONDITIONS DO ALLOW THE CONTAINMENT VESSEL TO LEAK ELECTROLYTES.
If it did not, it risks explosion. That is why the top of the container has a handful of screws holding it on and it overlaps the sides of the case so it can vent electrolyte. If it was designed to not allow a leak, they would have welded the top shut, as well.
What is NOT allowed to happen is that the leaked electrolytes subsequently take out a flight-critical system. And while JA804A didn't suffer damage to critical systems from the electrolyte, the FAA and NTSB are not convinced that it cannot happen.
spacecadet From United States of America, joined Sep 2001, 3249 posts, RR: 14 Reply 97, posted (3 months 2 weeks 6 days 19 hours ago) and read 15661 times:
Quoting justloveplanes (Reply 90): Update the containment (straightforward, maybe a bit time consuming, but straightforward and predictable)
Re-examine the problem from a loss of system redundancy point of view for flight safety vice a flight hazard and then conclude grounding or AD.
The NTSB has made it clear that they're not going to accept fires on airliners, period. As various people have said, there's always going to be that chance, however remote and with any kind of battery, so you're never going to make it impossible. But the NTSB's problem here is that the fire happened on the JAL flight, and then a week later something similar happened on an ANA flight. The only way you're going to satisfy the NTSB is to make the frequency of such events much, much less than that.
In other words, updating containment and re-examining redundancy are not going to solve the issue from the NTSB's perspective. What's going to solve the issue is making the problem occur with far lesser frequency. That means finding the root cause and fixing it.
The FAA could always go against the NTSB's recommendations and remove or revise the AD, and there's a chance that they might do that if things drag on for an indeterminate amount of time, but that would probably be a foolish PR move because they'd basically be telling people "we know we said we were grounding the plane for safety reasons, but... well, yeah, just go fly it anyway."
Think about it - that wouldn't be good for anyone, including Boeing or the airlines who fly the plane. In fact, it would put the airlines in a pretty terrible position.
[Edited 2013-01-28 16:36:56]
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 98, posted (3 months 2 weeks 6 days 19 hours ago) and read 15566 times:
Quoting rwessel (Reply 91): Doesn't matter, the battery is dead/dying/self-destructing at that point anyway.
Right, but if one cell is dying and the others are fine the potential short circuit could contribute to more doom, fireworks and fire. And there is no space on the side of the cell with the rupture valve. According to the slide in the NTSB presentation the two ports are next to the battery casing on one side and next to the adjacent cell on the other side. There's no empty space. The empty space is were the charging circuit board is at and on top of the battery where the terminals are at. This battery is crammed together like a sandwich.
Stitch From United States of America, joined Jul 2005, 26682 posts, RR: 83 Reply 99, posted (3 months 2 weeks 6 days 19 hours ago) and read 15660 times:
Quoting RickNRoll (Reply 96): Which does not answer the question. If the events now would have been pretty well identical to the tests then, why is it different now?
That I would like to know, myself.
JA804A operated for a year without a problem. 10 months with one battery and 3 months with another. And NH has three birds between 12 and 17 months with no issues.
And yet JA829J operated some two weeks before it had a problem. But JL has other birds going on 9+ months with no issues.
To my mind, something has to have changed. Some new variable has been introduced that significantly altered the probabilities of a battery issue. I've heard third-hand of a software update being applied to some 787s, but to date nobody else has picked it up so I don't know if there is any truth to it.
macc From Austria, joined Nov 2004, 970 posts, RR: 3 Reply 100, posted (3 months 2 weeks 6 days 19 hours ago) and read 15554 times:
[quote=DocLightning,reply=74]
what if they cant establish any reasonable cause?
in the end, they probably need more data. that is incidents. will they put the plane back into the air and await performance? guess they have to at some point. what about insurance companies? would they go along with such a decision without raising charges?
I exchanged political frustration with sexual boredom. better spoil a girl than the world
2175301 From United States of America, joined May 2007, 982 posts, RR: 0 Reply 101, posted (3 months 2 weeks 6 days 18 hours ago) and read 15386 times:
Quoting spacecadet (Reply 97): The NTSB has made it clear that they're not going to accept fires on airliners, period.
This may be a silly point - but I disagree that the NTSB has said that in the way you imply they have said it. The jet engines have fires in them. Piston engines have fires in them. APU's have fires in them. All totally acceptable.
Of course, if indeed their intent is to indeed ban all fires - then that would prevent such an event like this because there would be no aircraft at all (even gliders need an engine to pull them up).
Aesma From France, joined Nov 2009, 4774 posts, RR: 9 Reply 102, posted (3 months 2 weeks 6 days 18 hours ago) and read 15513 times:
I didn't think there would be a pressurization problem if the valve in one of the EE bay was blocked by a burning battery, if it came to that the pressure build-up would unblock it anyway. I was suggesting/wondering that it may lead to smoke not being evacuated in the designed way but instead going exactly where we don't want it to go.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 103, posted (3 months 2 weeks 6 days 18 hours ago) and read 15500 times:
Quoting Stitch (Reply 99): JA804A operated for a year without a problem. 10 months with one battery and 3 months with another. And NH has three birds between 12 and 17 months with no issues.And yet JA829J operated some two weeks before it had a problem. But JL has other birds going on 9+ months with no issues.To my mind, something has to have changed. Some new variable has been introduced that significantly altered the probabilities of a battery issue. I've heard third-hand of a software update being applied to some 787s, but to date nobody else has picked it up so I don't know if there is any truth to it.
You are talking about the cause, not the containment. That would have been tested too, wouldn't it?
Stitch From United States of America, joined Jul 2005, 26682 posts, RR: 83 Reply 104, posted (3 months 2 weeks 6 days 18 hours ago) and read 15496 times:
Quoting RickNRoll (Reply 103): You are talking about the cause, not the containment. That would have been tested too, wouldn't it?
I'm assuming it was as I can't see the FAA not requiring such validation.
I've asked for details, but so far nobody has provided any. I'm assuming that is because either nobody knows, or they're under an NDA.
I'd like to know how the leaking compared on the NH plane and the JL plane. The JL plane was on the ground with no airflow in the bay. So leaking electrolyte should have just dripped down the side and fallen to the floor. With no external forces acting on it, would it make it to the drain plugs, or just pool? And with no airflow, smoke, fumes and vapors would likely collect.
The NH plane had active airflow and flight forces in play. Did that affect the flow of electrolyte once it left the battery? Or did it to just drip down the sides and pool at the bottom? And with active air flow, smoke, fumes and vapors would have been purged via the outflow valves once activated by the flight deck (once they detected the initial smell).
Aesma From France, joined Nov 2009, 4774 posts, RR: 9 Reply 105, posted (3 months 2 weeks 6 days 18 hours ago) and read 15485 times:
Quoting 2175301 (Reply 101): This may be a silly point - but I disagree that the NTSB has said that in the way you imply they have said it. The jet engines have fires in them.
They're fine with very controlled combustion. When we say that an engine is on fire we rarely mean it's functioning as intended.
Quoting 2175301 (Reply 101): there would be no aircraft at all (even gliders need an engine to pull them up).
Some gliders can be launched by foot. Some gliders have electric engines and...you got it, Li-ion batteries allowing them to take off and go up to 3000m AGL.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
alberchico From United States of America, joined Sep 2004, 2681 posts, RR: 0 Reply 106, posted (3 months 2 weeks 6 days 18 hours ago) and read 15474 times:
packsonflight From Iceland, joined Jan 2010, 321 posts, RR: 0 Reply 107, posted (3 months 2 weeks 6 days 17 hours ago) and read 15382 times:
Quoting RickNRoll (Reply 94): Another question. Wouldn't Boeing have had to do a battery failure containment test during certification. Given the design of the container, I would assume it would have behaved pretty much the same then as it did in the recent events. Would it not have had flammable electrolyte leaking out in those tests, and have generated the same amount of heat. Why would that have been acceptable then, but not now?
Possibly this was never tested, and the FAA relayed on documents provided by Boeing. I guess now when on two occasions the battery have failed it did not happen as expected or described in the documents provided by Boeing.
Quoting spacecadet (Reply 97): The FAA could always go against the NTSB's recommendations and remove or revise the AD, and there's a chance that they might do that if things drag on for an indeterminate amount of time, but that would probably be a foolish PR move because they'd basically be telling people "we know we said we were grounding the plane for safety reasons, but... well, yeah, just go fly it anyway."
Why should FAA go against NTSB in the first place? isn't the aircraft grounded for a good reason? There are already allegations of cozy relationship between Boeing and FAA and it would be stupid for them to take a chance like that, and it would be reckless to do so without at least being able to pinpoint the reason for those two battery fires.
PanAmPaul From United States of America, joined Jan 2013, 77 posts, RR: 0 Reply 108, posted (3 months 2 weeks 6 days 17 hours ago) and read 15430 times:
Quoting alberchico (Reply 106): wait didn't the FAA grant a waiver allowing these birds to be flown back to their home bases ?
I'm not sure but the LOT 787 wasn't even covered by the FAA grounding and I was told it was still in Chicago as of two days ago.
cornutt From United States of America, joined Jan 2013, 215 posts, RR: 1 Reply 109, posted (3 months 2 weeks 6 days 17 hours ago) and read 15419 times:
Quoting RickNRoll (Reply 92): However, there is no controlled means of releasing pressure in the existing design.
Actually, if I understand this right, there is. There's an overboard vent connected to the containment; it's clearly visible in one of the photos on Aviation Herald. What controls it, and under what circumstances it opens, is the part that isn't clear to me. I don't think it's just an open hole.
cornutt From United States of America, joined Jan 2013, 215 posts, RR: 1 Reply 110, posted (3 months 2 weeks 6 days 17 hours ago) and read 15419 times:
Quoting alberchico (Reply 106): wait didn't the FAA grant a waiver allowing these birds to be flown back to their home bases ?
The FAA doesn't grant blanket waivers for those sorts of things; an airline that wanted to ferry their planes would have to ask for waivers for each flight, with specific information about the procedures to be used and the routing of the flight. Right now, I don't think there is any motivation to ferry them anywhere, since the airlines don't know where they will have to take them: is the work that will be needed something that they can do at their maintenance facilities, or will all the planes have to be flown back to Everett?
Viscount724 From Switzerland, joined Oct 2006, 21460 posts, RR: 24 Reply 111, posted (3 months 2 weeks 6 days 17 hours ago) and read 15382 times:
Quoting PanAmPaul (Reply 108): Quoting alberchico (Reply 106):
wait didn't the FAA grant a waiver allowing these birds to be flown back to their home bases ?
I'm not sure but the LOT 787 wasn't even covered by the FAA grounding and I was told it was still in Chicago as of two days ago.
The EASA (EU equivalent of the FAA) issued their own grounding order almost immediately after the FAA order was issued.
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 112, posted (3 months 2 weeks 6 days 17 hours ago) and read 15391 times:
Quoting Stitch (Reply 104): The JL plane was on the ground with no airflow in the bay. So leaking electrolyte should have just dripped down the side and fallen to the floor. With no external forces acting on it, would it make it to the drain plugs, or just pool?
If it was thin enough it would have found a body drain and dripped out of the airplane. I guessing that it was thick and grew thicker as it cooled and may not have made it to the body drain for that area.
Quoting Stitch (Reply 104): The NH plane had active airflow and flight forces in play. Did that affect the flow of electrolyte once it left the battery? Or did it to just drip down the sides and pool at the bottom? And with active air flow, smoke, fumes and vapors would have been purged via the outflow valves once activated by the flight deck (once they detected the initial smell).
Up until the smoke set off the smoke detector in the fwd E&E bay one of the cooling fans were blowing air over the equipment and into the cargo area. When smoke is detected the system automatically reconfigures and uses differencial pressure to suck the air past the equiptment and out of the airplane through the overboard venturi.
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 113, posted (3 months 2 weeks 6 days 17 hours ago) and read 15303 times:
Quoting cornutt (Reply 109): Actually, if I understand this right, there is. There's an overboard vent connected to the containment; it's clearly visible in one of the photos on Aviation Herald. What controls it, and under what circumstances it opens, is the part that isn't clear to me. I don't think it's just an open hole.
If its the photo of the airplane with the two insets showing "stains" down the side of the airplane, the botttom inset shows the fwd overboard vent valve and the upper one is form the overboard venturi which would have opened once smoke was detected. Neither is directly connected to the battery box.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 114, posted (3 months 2 weeks 6 days 16 hours ago) and read 15332 times:
Quoting asctty (Reply 83): Don't forget that if the Rupture Valve is activated then the battery is now useless in its function as a safety supply to the aircraft electrical system. Now that is really important is it not?
It's important for the main battery, not really for the APU battery. The APU battery really has no foreseeable purpose in flight, since the only time you'd need it is if the airplane managed to get all the way from normal configuration to no generators in less time than it takes to start the APU via some failure that would still allow the APU to run (i.e. you still have fuel) and still allow the power system to function (i.e. you're capable of even using the APU power). That's a pretty small failure space...small enough that, as far as I know, it's never happened in the history of modern airliners.
For the main battery, it also has no purpose in flight unless all the other electrical sources fail. This does play into the ultimate reliability of the power system but it's far out in the 1 in a million to 1 in a billion territory (among other things, if you're all the way down to battery power with no RAT you've completely lost ETOPS capability) so, though important, the probability of it actually coming up is extremely remote. The same special conditions that govern battery failure modes also require that the flight crew be notified any time the main battery isn't capable of doing it's job in the event that it's needed, so a crew would know they had no battery available and could take appropriate action (e.g. preemptively start the APU, drop the RAT, divert, etc.)
Quoting asctty (Reply 86): What if the battery was called upon to supply emergency power and permit safe landing of the aircraft?
If the battery had been on fire, it would not provide that function. However, in order to get to that state, you have to have all four engine generators fail and both APU generators fail (or the APU itself fail) and the RAT fail, all at the same time.
Quoting asctty (Reply 86): Please reassure me this is not the normal hazard assessment approach in the airline industry?
I'm not sure what you're referring to with "this" but yes, this is the normal hazard assessment approach in the airline industry. You ensure that no single failure, no matter how remote, can threaten safe flight and landing. Then you look at the probability of all foreseeable failure combinations and make sure that the probability is below thresholds corresponding to the magnitude of the effect...for threats to continued safe flight and landing, the probability of reaching that state is supposed to be extremely remote, which means less than 1 per billion flight hours.
Quoting RickNRoll (Reply 92): However, there is no controlled means of releasing pressure in the existing design. The case is sealed, until pressure forces it to deform, allowing flammable material to be released.
The case isn't sealed...steel that thin wouldn't stand up to pressurization cycles. The battery would blow up like a balloon the first time you took off.
Quoting RickNRoll (Reply 92): It allows heat damage to occur to surrounding equipment, so the case is not protecting the environment adequately either, in respect to the heat generated by a thermal runaway.
(5) No corrosive fluids or gases that may escape from any lithium
ion battery may damage surrounding structure or any adjacent systems,
equipment, or electrical wiring of the airplane in such a way as to
cause a major or more severe failure condition
and
(6) Each lithium ion battery installation must have provisions to
prevent any hazardous effect on structure or essential systems caused
by the maximum amount of heat the battery can generate during a short
circuit of the battery or of its individual cells.
Heat damage to surrounding equipment is allowed if that damage does not have any hazardous effect on the structure or system. So, for example, scorching of the rack is heat damage but is allowed by the special condition since it doesn't have a hazardous effect on any structure or system.
Quoting RickNRoll (Reply 92): The enhanced case is obviously the answer, but what would this require in respect of design, manufacturing, testing and certification?
That's not obviously the answer because it doesn't address the FAA & NTSB concern that the battery failure rate is too high.
Quoting RickNRoll (Reply 92): Would the FAA keep the 787 grounded till this whole process is complete.
Probably.
Quoting AeroWesty (Reply 93): Other than just looking at the photo of the EE bay from the JAL plane, has there been any indication what other than the battery pack was damaged, and how long it would take to repair the ancillary damage the plane sustained?
So far, there has been no indication that anything was damaged to the point of impairing it's function. There was scorching, burned blobs of battery goo in the bilge, etc. but no report that any other systems quit working or that any structure was damaged in a way that impaired it's ability to function.
Quoting RickNRoll (Reply 94): Wouldn't Boeing have had to do a battery failure containment test during certification.
Not necessarily. Containment is, in general, a pretty well established discipline so it could have been done by analysis. It also could have been tested at the assembly level (which is still part of certification but it would have been the battery vendor, not Boeing, doing the test).
Quoting RickNRoll (Reply 94): Would it not have had flammable electrolyte leaking out in those tests, and have generated the same amount of heat. Why would that have been acceptable then, but not now?
Because the FAA requirements were not that no heat escape or that no electrolyte escape. The requirements were that whatever does escape can't damage surrounding systems or structure in a hazardous way. So far, I don't see any reports that such damage occurred, which is why I'm curious what the FAA/NTSB are seeing that they're not saying yet.
Quoting RickNRoll (Reply 96):
Which does not answer the question. If the events now would have been pretty well identical to the tests then, why is it different now?
Because of other parts of the special condition:
(1) Safe cell temperatures and pressures must be maintained during
any foreseeable charging or discharging condition and during any
failure of the charging or battery monitoring system not shown to be
extremely remote. The lithium ion battery installation must preclude
explosion in the event of those failures.
(2) Design of the lithium ion batteries must preclude the
occurrence of self-sustaining, uncontrolled increases in temperature or
pressure.
Whether or not the containment worked as designed, the batteries did not maintain safe cell temperature (assuming this occurred during charge/discharge/failure of the BMS) and did have uncontrolled increases in temperature.
So the FAA/NTSB is rightly concerned that the batteries aren't behaving they were designed to do.
Quoting Aesma (Reply 102): I didn't think there would be a pressurization problem if the valve in one of the EE bay was blocked by a burning battery, if it came to that the pressure build-up would unblock it anyway. I was suggesting/wondering that it may lead to smoke not being evacuated in the designed way but instead going exactly where we don't want it to go.
All outflows are on the lower lobe. If one outflow valve plugged, the other valve would automatically open to maintain pressure and the flow patterns would switch around but everything should still stay on the lower lobe. If both outflow valves plugged (I'm not sure how that's physically possible but we'll assume so for the sake of argument) then the airplane would go up to maximum design pressure then the overpressure relief valves would open. They're also in the lower lobe so things should still stay on the lower deck. If the ECS system failed, an emergency scoop opens up to provide airflow (although not pressurization). If even that fails, the flight deck has an extra emergency scoop to keep the flight deck clear so the pilots can still fly.
Quoting Stitch (Reply 104): The NH plane had active airflow and flight forces in play. Did that affect the flow of electrolyte once it left the battery?
Flight forces might. Airflow probably wouldn't. Although the airflow is carefully designed, it's not like a noticeable wind in the EE bay. It's not going to blow electrolyte around, it's more like other "high" airflow environments like a cleanroom or OR.
Quoting Stitch (Reply 104): And with active air flow, smoke, fumes and vapors would have been purged via the outflow valves once activated by the flight deck (once they detected the initial smell).
Smoke would be caught by the smoke detectors and trigger reconfiguration. Smell/fumes/vapors might cause the flight crew to trigger it earlier if they noticed that and took action before they got all the way to smoke.
DocLightning From United States of America, joined Nov 2005, 16808 posts, RR: 57 Reply 115, posted (3 months 2 weeks 6 days 16 hours ago) and read 15110 times:
Quoting tdscanuck (Reply 114): The case isn't sealed...steel that thin wouldn't stand up to pressurization cycles. The battery would blow up like a balloon the first time you took off.
I just got the most hilarious mental image...
Quoting macc (Reply 100): what if they cant establish any reasonable cause?
Yes, well that's what I'm worried about. What if they simply cannot ascertain a cause? At what point do they give up?
Tom? Do you know what would happen in that eventuality? Has it ever happened?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 116, posted (3 months 2 weeks 6 days 16 hours ago) and read 15116 times:
Quoting packsonflight (Reply 107): Possibly this was never tested, and the FAA relayed on documents provided by Boeing.
The FAA almost never tests anything themselves as part of certification (they do their own R&D and investigation testing though). They, or their designates, witness the testing done by others.
NTSB's mission is purely accident investigation and safety; many of their recommendations, though technically correct, aren't viable for various reasons. FAA, not NTSB, is the one who decides what makes sense to actually implement. This practice is so old that the NTSB maintains a "Top 10" list of things they want that the FAA hasn't implemented.
Quoting packsonflight (Reply 107): There are already allegations of cozy relationship between Boeing and FAA
These allegations can only come from people who've never actually worked with a regulator.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 117, posted (3 months 2 weeks 6 days 15 hours ago) and read 14992 times:
Quoting tdscanuck (Reply 114): That's not obviously the answer because it doesn't address the FAA & NTSB concern that the battery failure rate is too high.
It's not the answer to the cause, I was referring to the containment requirement.
If the cause is never found, it will likely be even more important.
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 118, posted (3 months 2 weeks 6 days 15 hours ago) and read 14958 times:
Quoting tdscanuck (Reply 114): If the ECS system failed, an emergency scoop opens up to provide airflow (although not pressurization). If even that fails, the flight deck has an extra emergency scoop to keep the flight deck clear so the pilots can still fly.
If the both packs fail, pressurization can't be maintained and the pilot descends to the lowest safe altitude or 10.000 ft whichever is higher. Depending on the external temperature the cabin or the cockpit or both is liable to get too hot and the alternate ventilation system allows external air to flow through the airplane in an attempt to cool the interior. There is one switch that controls one valve that is flush mounted. This isn't Baskin & Robbins--you don't get two scoops and it is not used in smoke situations.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 119, posted (3 months 2 weeks 6 days 15 hours ago) and read 15002 times:
Quoting Stitch (Reply 95): BECAUSE THE SPECIAL CONDITIONS DO ALLOW THE CONTAINMENT VESSEL TO LEAK ELECTROLYTES
But the FAA says "The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes."
Am I reading this wrong? The release of electrolytes seems to be one of their major concerns, because they are flammable. Have they simply changed their minds between then and now, having seen the effects of the leakage.
gemuser From Australia, joined Nov 2003, 5217 posts, RR: 6 Reply 120, posted (3 months 2 weeks 6 days 15 hours ago) and read 14889 times:
Quoting cornutt (Reply 110): Right now, I don't think there is any motivation to ferry them anywhere, since the airlines don't know where they will have to take them
EASA would be authority to issue a wavier for the LOT aircraft BUT it would also need the agreement of all countries under the flight path, because of the AD. GC ORD-WAW would require agreement from USA, Canada, Denmark, Iceland, Norway & Sweden. You might be able to route around Norway & Sweden.
Too much trouble at the moment as, as cornutt says, they don't know where they will have to send the birds to get fixed.
rheinwaldner From Switzerland, joined Jan 2008, 2061 posts, RR: 6 Reply 121, posted (3 months 2 weeks 6 days 14 hours ago) and read 14767 times:
Quoting tdscanuck (Reply 82): Quoting mham001 (Reply 63):
I do think however having the BMS in the same box is absurd. This would not have have happened were I in charge of that design.
The farther you move the BMS from the battery, the more potential failure points you inject into the fault tree.
Probably minor ones compared to whatever happened. But I agree, that the BMS does not depend on its location for it to function. And that there is no longer a job to do for the BMS once a cell runs away.
Quoting Stitch (Reply 95): BECAUSE THE SPECIAL CONDITIONS DO ALLOW THE CONTAINMENT VESSEL TO LEAK ELECTROLYTES.
If it did not, it risks explosion.
Leaking electrolytes don't change the total volume in the vessel. So why on earth should that vessel explode because of electrolytes?
Which does not answer the question. If the events now would have been pretty well identical to the tests then, why is it different now?
Because of other parts of the special condition:
(1) Safe cell temperatures and pressures must be maintained during
any foreseeable charging or discharging condition and during any
failure of the charging or battery monitoring system not shown to be
extremely remote. The lithium ion battery installation must preclude
explosion in the event of those failures.
(2) Design of the lithium ion batteries must preclude the
occurrence of self-sustaining, uncontrolled increases in temperature or
pressure.
Whether or not the containment worked as designed, the batteries did not maintain safe cell temperature (assuming this occurred during charge/discharge/failure of the BMS) and did have uncontrolled increases in temperature.
So the FAA/NTSB is rightly concerned that the batteries aren't behaving they were designed to do.
Requirement (1) and (2) cover also the requirement (6) somehow redundantly and in a more generic way. Requirement (6) only adds a further condition, under which (1) and (2) specifically are not allowed to happen. While (1) and (2) rule out any cause of a thermal runaway in a very generic, broad way already in the first place.
IMO the requirements are not 100% solid and may require adjustments:
e.g. (2) lays the focus of preventing a thermal runaway on the design of the battery. As if a thermal runaway induced by a failing BMS would be ok. In reality the larger responsibility and risk lays on the side of the charger. So its design should have been included in (2). Because we do agree that thermal runaways coming from misdesigned batteries is equally bad as thermal runaways that come from something else, don't we?
DocLightning From United States of America, joined Nov 2005, 16808 posts, RR: 57 Reply 122, posted (3 months 2 weeks 6 days 14 hours ago) and read 14771 times:
Quoting rheinwaldner (Reply 121): Leaking electrolytes don't change the total volume in the vessel. So why on earth should that vessel explode because of electrolytes?
Because in order to contain all of the temperature and pressure in that fire, it would have to be made of 6"-thick steel plate.
justloveplanes From United States of America, joined Jul 2004, 871 posts, RR: 1 Reply 123, posted (3 months 2 weeks 6 days 14 hours ago) and read 14757 times:
Quoting spacecadet (Reply 97): The NTSB has made it clear that they're not going to accept fires on airliners, period. As various people have said, there's always going to be that chance, however remote and with any kind of battery, so you're never going to make it impossible.
That makes sense of course, and totally understandable. It might be possible to take the position, however, that a contained combustion event is not a fire (such as the burning of tons of aircraft fuel as was mentioned). You can design, without much magic and feasibly, containment that makes any battery combustion event non-hazardous in and of itself.
It will add significant weight to the aircraft, maybe 50 - 100 lbs. But it wont be any more of a thermal event from a safety perspective, than say, a warming oven for inflight meals.
Of course, long term, with that containment requirement for LiIon, and all that extra weight and complexity, might as well just go NiCad.
I think NiCads are the ultimate solution, LiIon too flaky. What ever is burning up those batteries is doing it in a pretty stable electrical environment it seems (unless measurements are wrong for the charging loop and indeed the thing is being overcharged, we should know that shortly).
NiCad's aside, new containment is something Boeing might need to do now to get out its current fix. Take the fire event out of the equation by transforming the environment.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 124, posted (3 months 2 weeks 6 days 13 hours ago) and read 14407 times:
Quoting Stitch (Reply 95): If it did not, it risks explosion. That is why the top of the container has a handful of screws holding it on and it overlaps the sides of the case so it can vent electrolyte. If it was designed to not allow a leak, they would have welded the top shut, as well. What is NOT allowed to happen is that the leaked electrolytes subsequently take out a flight-critical system. And while JA804A didn't suffer damage to critical systems from the electrolyte, the FAA and NTSB are not convinced that it cannot happen.
In any container that can have an overpressure event, you obviously do not weld it shut, but you have exhausts for the gases and spare storage room for any escaping liquids. I am quite shocked reading up on the requirements the FAA put up for the battery installation. This is less than what is expected by various US agencies for lead acid batteries in buildings or telecom applications:
NiMh has an even greater power density than Li-ion...but has a much lower power to weight ratio. They are slightly heavier than NiCd's, just as reliable but much superior power density, same voltage per cell and use the same chargers.
I have no idea if they are certified for aircraft but it's just about impossible to find NiCd's used on earth anymore.
gigneil From United States of America, joined Nov 2002, 16215 posts, RR: 88 Reply 126, posted (3 months 2 weeks 6 days 11 hours ago) and read 13863 times:
Quoting beau222 (Reply 43): Does the 748 series use the same type of battery or batteries that the 787 is having issues with?
Quoting Stitch (Reply 62): No. I's probably NiCad (747s before the 747-400 use lead acid).
It is a Saft CVH531KA, a 20-cell, 53 Ah 24V NiCad rechargeable pack. It weights exactly 96 pounds.
BEG2IAH From United States of America, joined Apr 2004, 827 posts, RR: 12 Reply 127, posted (3 months 2 weeks 6 days 11 hours ago) and read 14035 times:
Quoting rheinwaldner (Reply 121): Leaking electrolytes don't change the total volume in the vessel. So why on earth should that vessel explode because of electrolytes?
It has been mentioned 50+ times in these threads that thermal runaway results in release of gasses and many posters want to have the battery sealed so nothing leaks. Gasses build pressure if they are produced in a sealed pressure vessel and eventually if vessel fails you have an explosion. Volume of electrolyte has nothing to do with pressures built by thermal runaway. How hard can it be to understand this?
Quoting RickNRoll (Reply 119): But the FAA says "The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes."
After 300 posts, you are still asking the same questions. Let's try again: yes, it did. As Tom quoted from the special requirements (emphasis mine):
(5) No corrosive fluids or gases that may escape [MAY ESCAPE, meaning they are allowed to leak!!!] from any lithium ion battery may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition
I really don't understand what's not clear in the above sentence.
[Edited 2013-01-29 00:52:46]
Use of approved electronic devices is now permitted.
rheinwaldner From Switzerland, joined Jan 2008, 2061 posts, RR: 6 Reply 128, posted (3 months 2 weeks 6 days 11 hours ago) and read 13992 times:
Quoting DocLightning (Reply 122): Because in order to contain all of the temperature and pressure in that fire
You speak about fire, pressure and temperature. I only about leaked electrolytes. These are two things.
Stitch wrote with large letters, that leaking electrolytes would lead to an explosion.
Thruth is, that leaking electrolytes are a result of a fire and heat in the first place. And the containment sure would exlode without some venting. But not because of the electrolytes. Responsible for that would be first the heat and the fire, which then produce gases that increase the volume, with results in pressure. Leaking electrolyte are not involved in that chain.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 129, posted (3 months 2 weeks 6 days 10 hours ago) and read 13859 times:
Quoting BEG2IAH (Reply 127): It has been mentioned 50+ times in these threads that thermal runaway results in release of gasses and many posters want to have the battery sealed so nothing leaks. Gasses build pressure if they are produced in a sealed pressure vessel and eventually if vessel fails you have an explosion. Volume of electrolyte has nothing to do with pressures built by thermal runaway. How hard can it be to understand this?
I dare say that it is not really rocket science to built a containment vessel that keeps the liquids in and lets the gas out. Even if the liquids should increase their volume with a temeprature increase, it is not hard to make provisions for that as well.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 130, posted (3 months 2 weeks 6 days 10 hours ago) and read 13727 times:
Quoting BEG2IAH (Reply 127): (5) No corrosive fluids or gases that may escape [MAY ESCAPE, meaning they are allowed to leak!!!] from any lithium ion battery may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition
I really don't understand what's not clear in the above sentence.
It doesn't say "fluids or gases that may escape", it says "NO corrosive fluids or liquids that may escape", there is a big negative at the start of that sentence. So I asked, in his terms, does that mean that they have changed their minds, since their statement clearly indicates that corrosive fluids or liquids that have escaped are an issue for them.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 131, posted (3 months 2 weeks 6 days 10 hours ago) and read 13640 times:
Well it would also depend on what you define as the battery. If the baterry is just the cells and the charger and the metal box around it is the containment, than this actually makes sense. Becuase the cells will leak in a failure, so demanding that they do not leak, would be impossible.
justloveplanes From United States of America, joined Jul 2004, 871 posts, RR: 1 Reply 132, posted (3 months 2 weeks 6 days 9 hours ago) and read 13469 times:
Quoting JoeCanuck (Reply 125): NiMh has an even greater power density than Li-ion...but has a much lower power to weight ratio. They are slightly heavier than NiCd's, just as reliable but much superior power density, same voltage per cell and use the same chargers.
NiMH does sound interesting. Obviously seems more stable than LiIon? Less prone to runaway? Same current delivery (Per Ah reserve) and recharge cycle capable? Re: you said slightly heavier that NiCad, on what basis? lb/Amp-hour?
Quoting gigneil (Reply 126): It is a Saft CVH531KA, a 20-cell, 53 Ah 24V NiCad rechargeable pack. It weights exactly 96 pounds.
Design questions, why use NiCads instead of NiMh on the 748? Certification?
I recall that the statement was made that other chemistries couldn't work in the 787, I have to assume that means same weight, etc and a few other items. If you can deliver voltage and current and have a decent recharge cycle life, what else is a factor in the 787? Are there complex loads that require driving in a certain impedence and current profile? If it's just to start a big gas engine like an APU, I can't imagine that is the case.
Why else would NiMh/NiCad not work in the 787 if you are willing to live with the weight penalty? What would the weight difference be for similar current delivery and Ah reserve of these chemistries vs Li-Ion?
keegd76 From UK - Northern Ireland, joined Aug 2009, 83 posts, RR: 0 Reply 133, posted (3 months 2 weeks 6 days 6 hours ago) and read 12733 times:
Quoting flyglobal (Reply 16): For Air Planes the design requirements are different - less environmental temperature span at the battery location
Just my own 2 cents.
Based on my own line of work there would [probably] have been a separate environmental requirement for the battery as opposed to the plane. But it would have been dictated by Boeing as the end user. So I'm wondering if the requirement was based on the batteries used in their other planes?
Having said that, I know from experience that when designing/providing a system to a customer, we test the system/component not just to confirm that it works as designed but also to prove that if something goes wrong it will fail in a controlled manner without risk to the user. I absolutely guarantee that Yuasa's tests covered not just battery failure but catastrophic battery failure. Boeing would have expected proof before accepting.
Quoting vivekman2006 (Reply 37):
100C is the temperature at which water boils and is absolutely un-survivable! The highest temperature ever recorded on Earth is 56.7C (134F) in Death Valley, CA
prebennorholm From Denmark, joined Mar 2000, 6016 posts, RR: 55 Reply 134, posted (3 months 2 weeks 6 days 5 hours ago) and read 12416 times:
Quoting justloveplanes (Reply 132): Design questions, why use NiCads instead of NiMh on the 748? Certification?
NiMH has higher capacity than NiCad. But unfortunately NiMH has by far the highest internal resistance when cold of all relevant battery types, including Lead-acid.
For winter use they would have to be vastly oversized compared to NiCad in order to deliver the amps needed. That's the reason why NiMH has never been considered relevant as starter battery for airliners.
NiCad is vastly superior for short duration high power applications.
For starting at 0 deg. F ( -18 deg. C) a NiMH battery would be two or three times heavier than a NiCad. It would, however, do more consecutive starts without recharging, but that's not a selling point.
NiMH is the perfect choise for household application where low temperature is not an issue, and where weight issues don't call for Li-Ion.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 135, posted (3 months 2 weeks 6 days 5 hours ago) and read 12465 times:
Quoting DocLightning (Reply 115): What if they simply cannot ascertain a cause? At what point do they give up?
Tom? Do you know what would happen in that eventuality? Has it ever happened?
I was just talking about that with some friends last night...the short answer is, I don't know, because I don't think anyone has been in this situation before. All other prior groundings (that we could think of) were preceded by multiple fatal crashes. We couldn't think of a prior grounding with (relatively) so little known cause. That's not a criticism of the grounding, the industry has progressed a lot in safety since then, but it sets up an interesting problem. In this case, the FAA has somewhat painted themselves into a corner...they really can't lift the grounding until they know root cause and have a fix. But there's a non-zero chance that they won't be able to find root cause. And I don't think anyone (yet) know's what to do then. I have no idea how you'd handle the certification or PR in that situation...in some respects, it would be worse than the DC-10 type situation where, at least, you could point to the cause, point to the fix, and say, "See, we're good now."
Quoting 7BOEING7 (Reply 118): Depending on the external temperature the cabin or the cockpit or both is liable to get too hot and the alternate ventilation system allows external air to flow through the airplane in an attempt to cool the interior. There is one switch that controls one valve that is flush mounted. This isn't Baskin & Robbins--you don't get two scoops and it is not used in smoke situations.
The alternate ventilation scoop/vent/take-your-pick (the one with the switch) is down on the lower fuselage. The other one is manual and built into the flight deck escape hatch (you need to pull down the cover to access it). It's called the "flight deck overhead vent" and is part of the "cabin too hot" checklist, which shows up in (among other things) the depressurization checklist. You're correct that it's not an explicit part of the smoke checklist but several other parts of the smoke checklist, notably putting the EE cooling into alternate ventilation, may result in heat buildup in the flight deck. If I were a flight crew, I'd also seriously consider using the overhead vent if the other smoke/fume removal steps were not successful.
Quoting RickNRoll (Reply 119): Quoting Stitch (Reply 95):
BECAUSE THE SPECIAL CONDITIONS DO ALLOW THE CONTAINMENT VESSEL TO LEAK ELECTROLYTES
But the FAA says "The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes."
And the FAA's statement is absolutely true. It's a factual statement about what happened. That's quite a bit different than a statement that the release caused hazardous damage to any other systems or structure, which is what would be required to violate that part of the special conditions (it may have, but they haven't said that and we probably won't know until more investigation results come out).
Quoting RickNRoll (Reply 119): Am I reading this wrong? The release of electrolytes seems to be one of their major concerns, because they are flammable. Have they simply changed their minds between then and now, having seen the effects of the leakage.
Their major concern, as they said, is that the released electrolytes *could* (not "did") result in damage to other systems. This suggests that something with the initial fault tree analysis isn't right, or at least the FAA isn't convinved it was right...it's pretty obvious that the probability of battery failures must have been wrong, but they may also have seen something in the incidents that suggests the connection between electrolyte release and damage to other equipment may not have been correct...but if they have, they're not talking about it yet.
Quoting rheinwaldner (Reply 121): Quoting Stitch (Reply 95):
BECAUSE THE SPECIAL CONDITIONS DO ALLOW THE CONTAINMENT VESSEL TO LEAK ELECTROLYTES.
If it did not, it risks explosion.
Leaking electrolytes don't change the total volume in the vessel. So why on earth should that vessel explode because of electrolytes?
Absent physical compromise of the battery case, electrolytes leak because of a thermal runaway. Thermal runaway is hot enough to vapourize part of the electrolytes, which means you're releasing gas in the battery case. You're also heating the air that was already in the battery case. Both of those mean a pressure rise if you've got a sealed case. It's not that the electolyte, by itself, spontaneously causes a pressure rise. But the fact of leaking electrolyte, in this context, means you've also got enough heat to cause a pressure rise, where one of the big contributors is vapourized electrolyte.
Quoting rheinwaldner (Reply 121): Because we do agree that thermal runaways coming from misdesigned batteries is equally bad as thermal runaways that come from something else, don't we?
The end result, yes. Ability to fix is better mis-designed batteries (since it's a contained LRU) rather than something else (which would imply more of a system effect).
Quoting justloveplanes (Reply 123): It might be possible to take the position, however, that a contained combustion event is not a fire (such as the burning of tons of aircraft fuel as was mentioned).
I think you'd have to admit it's a fire, just like combustion in the engines, just that it's acceptable if you can "guarantee" it's fully contained and the system level effects are acceptable.
Quoting rheinwaldner (Reply 128): Stitch wrote with large letters, that leaking electrolytes would lead to an explosion.
Thruth is, that leaking electrolytes are a result of a fire and heat in the first place. And the containment sure would exlode without some venting. But not because of the electrolytes.
This started from the claim that the battery box should be (or was) sealed. If you have leaking electrolytes from a sealed battery case, that means you built up pressure of hot, flammable gas inside a box with it's own oxidizer...that's a recipe for an explosion.
Quoting seahawk (Reply 129): I dare say that it is not really rocket science to built a containment vessel that keeps the liquids in and lets the gas out. Even if the liquids should increase their volume with a temeprature increase, it is not hard to make provisions for that as well.
Agreed. I strongly suspect that's got to be one of the possible fixes being examined. It's a different (heavier) way to implement the containment but might be what's required to satisfy the FAA/NTSB now.
Stitch From United States of America, joined Jul 2005, 26682 posts, RR: 83 Reply 136, posted (3 months 2 weeks 6 days 5 hours ago) and read 12403 times:
Quoting RickNRoll (Reply 130): It doesn't say "fluids or gases that may escape", it says "NO corrosive fluids or liquids that may escape", there is a big negative at the start of that sentence. So I asked, in his terms, does that mean that they have changed their minds, since their statement clearly indicates that corrosive fluids or liquids that have escaped are an issue for them.
The grammar is perfectly clear to me - if corrosive fluids or liquids do escape they may not damage surrounding structures.
So the FAA and NTSB have not changed their position. What has changed is their confidence level about any escaping fluids or gases not damaging surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition.
If the intention was to say no corrosive fluids or liquids may escape, that entire section would be written as such: "No corrosive fluids or liquids may escape from any lithium ion battery."
vzlet From United States of America, joined Mar 2004, 820 posts, RR: 0 Reply 137, posted (3 months 2 weeks 6 days 4 hours ago) and read 12148 times:
Quoting tdscanuck (Reply 135): Quoting seahawk (Reply 129):I dare say that it is not really rocket science to built a containment vessel that keeps the liquids in and lets the gas out. Even if the liquids should increase their volume with a temeprature increase, it is not hard to make provisions for that as well.
Agreed. I strongly suspect that's got to be one of the possible fixes being examined. It's a different (heavier) way to implement the containment but might be what's required to satisfy the FAA/NTSB now.
Any reason why it wouldn't work to just enlarge the dimensions of the battery case by an inch or two and and use it as a (secondary) container for the existing battery? Gas would still be vented and any electrolyte escaping the inner case would be contained in the outer.
"That's so stupid! If they're so secret, why are they out where everyone can see them?" - my kid
Shenzhen From United States of America, joined Jun 2003, 1701 posts, RR: 2 Reply 138, posted (3 months 2 weeks 6 days 3 hours ago) and read 11856 times:
Quoting tdscanuck (Reply 135): I was just talking about that with some friends last night...the short answer is, I don't know, because I don't think anyone has been in this situation before. All other prior groundings (that we could think of) were preceded by multiple fatal crashes. We couldn't think of a prior grounding with (relatively) so little known cause. That's not a criticism of the grounding, the industry has progressed a lot in safety since then, but it sets up an interesting problem. In this case, the FAA has somewhat painted themselves into a corner...they really can't lift the grounding until they know root cause and have a fix. But there's a non-zero chance that they won't be able to find root cause. And I don't think anyone (yet) know's what to do then. I have no idea how you'd handle the certification or PR in that situation...in some respects, it would be worse than the DC-10 type situation where, at least, you could point to the cause, point to the fix, and say, "See, we're good now."
Me thinks they will add a bunch of inspections (maint) and procedures (flight crew) and once an airline has met the requirements they will be allowed to resume ops.
Longer term (different ADs) could be that they add additional monitoring (dual) and probably lower some of the control limits, such as thermal protection and probably add some drip shields.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 139, posted (3 months 2 weeks 6 days 3 hours ago) and read 11864 times:
Quoting vzlet (Reply 137): Any reason why it wouldn't work to just enlarge the dimensions of the battery case by an inch or two and and use it as a (secondary) container for the existing battery?
The only obvious issue I can see is that I'm sure there's some clearance requirement between the battery and surrounding parts, precisely to avoid meaningful heat damage to other parts from a runaway battery. I'm not sure how much room there is between the existing case and the point where they have to start revisiting the clearances or moving other things.
strfyr51 From United States of America, joined Apr 2012, 488 posts, RR: 0 Reply 140, posted (3 months 2 weeks 6 days 3 hours ago) and read 11885 times:
look guys,
Everybody is going on and ON about the Lithium-Ion Batteries and their safety, But NOBODY seems to question the Manufacturer OF said batteries and whether THEY had any culpability in their Manufacturing process According to Aviation Week 21Jan,2013, GS YASA of Japan was the manufacturer. I've seen nowhere that their manufacturing and testing process was reviewed or compared to a company like SAFT to determine it's effectiveness or to root out flaws. The airplanes involved were among the first to be delivered. There have only BEEN 51 deliveries to date. United (whom I work for) has had other problems with the airplane due to it's new systems technology got NOT with the batteries so it could be that a change in manufacturers might more be in order than the Lithium ion battery itself or install a third Ni cad battery in the rear compartment for the extra OOMPH starting the engines, apu or ground operation might take and drive ON! I know Boeing might not want to hear this but they're going to be on the hook for 51 airplanes sitting gathering DUST if the don't do something PDQ.
cornutt From United States of America, joined Jan 2013, 215 posts, RR: 1 Reply 141, posted (3 months 2 weeks 6 days 3 hours ago) and read 11840 times:
Quoting rheinwaldner (Reply 121): Probably minor ones compared to whatever happened. But I agree, that the BMS does not depend on its location for it to function. And that there is no longer a job to do for the BMS once a cell runs away.
Don't underestimate the amount of work that it might take to do that. Some sensors, particularly passive things like thermocouples, often rely on the physical conductor distance between the sensor and the receiving circuit being very short. If you move the electronics further away, now you might need additional signal conditioning circuitry, and you might also potentially run into grounding/EMI problems.
Some years ago my dad was involved in something like this. Some people that were setting up a Space Shuttle Main Engine test stand wanted to move the controller off of the engine and into a room inside the hard stand, so that the controller would survive if the engine blew. They had no end of problems with it, and my dad was called in to help straighten things out. It took about six months to get it all working.
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 142, posted (3 months 2 weeks 6 days 3 hours ago) and read 11692 times:
Quoting tdscanuck (Reply 135): I was just talking about that with some friends last night...the short answer is, I don't know, because I don't think anyone has been in this situation before. All other prior groundings (that we could think of) were preceded by multiple fatal crashes.
But would it be any different if the grounding were the result of a crash due to a battery fire? They would still have to find the root cause, no?
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 143, posted (3 months 2 weeks 6 days 3 hours ago) and read 11659 times:
Quoting strfyr51 (Reply 140): The airplanes involved were among the first to be delivered. There have only BEEN 51 deliveries to date.
No, the ANA plane was one of the first delivered. And there have been 50 deliveries.
Quoting strfyr51 (Reply 140): install a third Ni cad battery in the rear compartment for the extra OOMPH starting the engines, apu or ground operation might take and drive ON!
As a passenger, I don't even know what to make of malarkey such as this. I hope that's not the general attitude at United.
Aesma From France, joined Nov 2009, 4774 posts, RR: 9 Reply 144, posted (3 months 2 weeks 6 days 3 hours ago) and read 11596 times:
Quoting tdscanuck (Reply 139): The only obvious issue I can see is that I'm sure there's some clearance requirement between the battery and surrounding parts, precisely to avoid meaningful heat damage to other parts from a runaway battery. I'm not sure how much room there is between the existing case and the point where they have to start revisiting the clearances or moving other things.
You could make it an aluminum box with some fins in the direction that is clear of obstacles, it would help dissipate the heat of potential leaks.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
max999 From United States of America, joined Dec 2005, 906 posts, RR: 0 Reply 145, posted (3 months 2 weeks 6 days 2 hours ago) and read 11515 times:
I'm appalled and angry that some people on here have suggested that the 787 was grounded prematurely and then comparing to past aircraft (737 crashes, DC10 crashes, etc, etc) which weren't grounded even after fatal accidents. The fact is that scores of people needlessly DIED due to problems with those aircraft. Deaths occurred before issues were identified and fixed.
While we still don't know the causes of the battery problems...I'm thankful we live in a different and safer aviation world now where issues are caught before a single fatality.
All the things I really like to do are either immoral, illegal, or fattening.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 146, posted (3 months 2 weeks 6 days 1 hour ago) and read 11026 times:
Quoting Aesma (Reply 144): You could make it an aluminum box with some fins in the direction that is clear of obstacles, it would help dissipate the heat of potential leaks.
Steel box. Wrapping flaming lithium with potentially flaming aluminum will likely not pass muster with the FAA.
Quoting max999 (Reply 145): I'm appalled and angry that some people on here have suggested that the 787 was grounded prematurely and then comparing to past aircraft (737 crashes, DC10 crashes, etc, etc) which weren't grounded even after fatal accidents.
Well, groundings don't happen very often...what else are we going to compare to? The point isn't so much that the 787 shouldn't be grounded, it's that the goalposts around grounding have obviously moved and it's legitimate to talk about how far they moved and whether they moved too far.
Quoting max999 (Reply 145): While we still don't know the causes of the battery problems...I'm thankful we live in a different and safer aviation world now where issues are caught before a single fatality.
Most issues are caught before a fatality *without* a grounding. The FAA drops AD's on a very regular basis, they haven't grounded an entire type for decades. I don't think anybody is arguing that the FAA shouldn't have taken action. I think there is legitimate discussion around whether the action they did take was too conservative or "just right" (I don't think anyone has argued their action wasn't strong enough, just maybe not fast enough). However, as I've said before, they had to take some action and, now that they've done it, they should see it through to the end properly and not try to second guess themselves. These issues are, fortunately, relatively rare so we'd be remiss to not learn all we can about this specific problem *and* the process so that the whole industry can do better next time.
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 148, posted (3 months 2 weeks 6 days ago) and read 10768 times:
Quoting tdscanuck (Reply 146): The FAA drops AD's on a very regular basis, they haven't grounded an entire type for decades.
ADs have very specific actions / fixes specified. The FAA cannot issue an AD if they don't know what to recommend to fix the problem. Therefore their only choice (short of risking more potentially catastrophic battery fires) is a grounding.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 149, posted (3 months 2 weeks 5 days 23 hours ago) and read 10480 times:
Quoting sankaps (Reply 148): The FAA cannot issue an AD if they don't know what to recommend to fix the problem.
Sure they can. For example:
"As a result of an in-flight, Boeing 787 battery incident earlier today in Japan, the FAA will issue an emergency airworthiness directive (AD) to address a potential battery fire risk in the 787 and require operators to temporarily cease operations. Before further flight, operators of U.S.-registered, Boeing 787 aircraft must demonstrate to the Federal Aviation Administration (FAA) that the batteries are safe." http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14233
An AD is simply a notification that there are aircraft that don't comply with regulations. It's strongly preferred that the AD include the action to restore compliance but that's not required.
Quoting sankaps (Reply 148): Therefore their only choice (short of risking more potentially catastrophic battery fires) is a grounding.
They had lots of choices...the AD could have imposed an operating limitation like "inspect the battery after every flight" or something like that. I'm not suggesting that that would actually work in this case, just that they can specify actions without fixing the problem.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 150, posted (3 months 2 weeks 5 days 22 hours ago) and read 10121 times:
Quoting Aesma (Reply 144): You could make it an aluminum box with some fins in the direction that is clear of obstacles, it would help dissipate the heat of potential leaks.
Or make it out of expandable kevlar. So when the battery blows the container just expands rather then rupture.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 151, posted (3 months 2 weeks 5 days 22 hours ago) and read 10113 times:
Quoting BEG2IAH (Reply 127): It has been mentioned 50+ times in these threads that thermal runaway results in release of gasses and many posters want to have the battery sealed so nothing leaks. Gasses build pressure if they are produced in a sealed pressure vessel and eventually if vessel fails you have an explosion. Volume of electrolyte has nothing to do with pressures built by thermal runaway. How hard can it be to understand this?
because in other Li-Ion battery failures the battery did not explode but rather became so hot that it started combusting adjacent material.
SonomaFlyer From United States of America, joined Apr 2010, 1171 posts, RR: 0 Reply 152, posted (3 months 2 weeks 5 days 21 hours ago) and read 10020 times:
The containment box has to be made from a material which will not chemically react with the battery electrolyte nor catch fire itself.
Aluminium isn't the best material for the job. Steel is one possibility and there are others which can perform the containment function.
justloveplanes From United States of America, joined Jul 2004, 871 posts, RR: 1 Reply 153, posted (3 months 2 weeks 5 days 19 hours ago) and read 9739 times:
Quoting SonomaFlyer (Reply 152): Steel is one possibility and there are others which can perform the containment function.
Extensive use of fins for heat transfer to can direct high temperatures away from other surfaces also.
rcair1 From United States of America, joined Oct 2009, 917 posts, RR: 25 Reply 154, posted (3 months 2 weeks 5 days 19 hours ago) and read 9625 times:
AIRLINERS.NET CREW CUSTOMER SERVICE & SUPPORT
(5) No corrosive fluids or gases that may escape from any lithium ion battery may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition
Quoting RickNRoll (Reply 130): It doesn't say "fluids or gases that may escape", it says "NO corrosive fluids or liquids that may escape", there is a big negative at the start of that sentence. So I asked, in his terms, does that mean that they have changed their minds, since their statement clearly indicates that corrosive fluids or liquids that have escaped are an issue for them.
If the word "that" was not in the sentence, your interpretation would be correct.
But it is not correct, because "that" is there.
Maybe it is easier if you pull out the subject and break it into phrases.
No corrosive fluids or gases that may escape from any lithium ion battery.....
[nothing that escapes]
may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane ....
[may damage stuff around it]
in such a way as to cause a major or more severe failure condition,
[in a bad way]
"Nothing that escapes may damage stuff around it in a bad way."
If stuff does escape - but does not damage anything around it
... you are okay
If stuff does escape - and damages stuff around it,
... but does not damage it in way that make the airplane go bad
... you are okay.
Making a mark, making a stain, such-n-stuff - is allowed.
Maybe item 5 needs to be re-written - and it may as a result of this - but that is the way it is written.
JoeCanuck From Canada, joined Dec 2005, 4993 posts, RR: 29 Reply 155, posted (3 months 2 weeks 5 days 19 hours ago) and read 9561 times:
Quoting justloveplanes (Reply 132): NiMH does sound interesting. Obviously seems more stable than LiIon? Less prone to runaway? Same current delivery (Per Ah reserve) and recharge cycle capable? Re: you said slightly heavier that NiCad, on what basis? lb/Amp-hour?
Right...lb/amp hour.
Quoting justloveplanes (Reply 132): Design questions, why use NiCads instead of NiMh on the 748? Certification?
NiMh may not be certified and NiCd's are tried and true...it's hard to beat something that just works, doesn't cause any drama when it doesn't work and creates no safety concerns.
Quoting justloveplanes (Reply 132): Why else would NiMh/NiCad not work in the 787 if you are willing to live with the weight penalty? What would the weight difference be for similar current delivery and Ah reserve of these chemistries vs Li-Ion?
NiCd would work...but they have never been certified for the 787.
Quoting prebennorholm (Reply 134): NiMH has higher capacity than NiCad. But unfortunately NiMH has by far the highest internal resistance when cold of all relevant battery types, including Lead-acid.
This is true...something I failed to take into account, but NiMh batteries are getting better.
Quoting strfyr51 (Reply 140): Everybody is going on and ON about the Lithium-Ion Batteries and their safety, But NOBODY seems to question the Manufacturer OF said batteries and whether THEY had any culpability in their Manufacturing process According to Aviation Week 21Jan,2013, GS YASA of Japan was the manufacturer.
I have read quite a bit about the maker of the batteries being investigated.
Quoting max999 (Reply 145): I'm appalled and angry that some people on here have suggested that the 787 was grounded prematurely
I don't recall reading any opinions that suggest the 787 shouldn't have been grounded.
Quoting SonomaFlyer (Reply 152): Aluminium isn't the best material for the job. Steel is one possibility and there are others which can perform the containment function.
Some composites can take very high temperatures, as can some silicone compounds....but it's hard to beat the reliability and predictability of steel.
I believe the black boxes are still made of steel.
BEG2IAH From United States of America, joined Apr 2004, 827 posts, RR: 12 Reply 157, posted (3 months 2 weeks 5 days 18 hours ago) and read 9495 times:
Quoting ComeAndGo (Reply 150): Or make it out of expandable kevlar. So when the battery blows the container just expands rather then rupture.
So after all this discussion you are suggesting that battery should be sealed and you expect FAA to certify a bomb to be used on an aircraft? Interesting...
Quoting ComeAndGo (Reply 150): because in other Li-Ion battery failures the battery did not explode but rather became so hot that it started combusting adjacent material.
Could you please provide an example of a battery the size of what's on B787 that was sealed and went into a thermal runaway. Laptop battery doesn't count.
Use of approved electronic devices is now permitted.
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 158, posted (3 months 2 weeks 5 days 18 hours ago) and read 9460 times:
Quoting ComeAndGo (Reply 150): Or make it out of expandable kevlar. So when the battery blows the container just expands rather then rupture.
There are two potential problems there...unless you're very clever with the Kevlar design, it would be really hard to guarantee the expanding case doesn't run into something around it. And Kevlar doesn't do heat very well.
Quoting ComeAndGo (Reply 151): because in other Li-Ion battery failures the battery did not explode but rather became so hot that it started combusting adjacent material.
The batteries didn't explode because normal batteries vent, they don't remain sealed when pressure starts to build.
Quoting JoeCanuck (Reply 155): Quoting max999 (Reply 145):
I'm appalled and angry that some people on here have suggested that the 787 was grounded prematurely
I don't recall reading any opinions that suggest the 787 shouldn't have been grounded.
In max999's defense, the suggestion got made, although I can't find the post so it's either buried somewhere or the post got deleted.
spacecadet From United States of America, joined Sep 2001, 3249 posts, RR: 14 Reply 159, posted (3 months 2 weeks 5 days 18 hours ago) and read 9409 times:
Here's a wrinkle that I personally haven't seen talked about, and I believe I have been following these threads I thought pretty closely:
The Verge has a sensationalist headline (obviously) but the real story here is that Elon Musk, who designs electric cars with lithium ion batteries for a living, says a simple change to more and smaller cells with more space in between would go a long way towards solving this problem. The real problem with the 787 battery, he says, is that the cells are so large and so close together than if one goes, all of them go in a domino effect due to the amount of energy contained in each cell and the ease of transferring that energy from one cell to the next. Smaller cells spaced further apart would fix that.
What say you, engineers?
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
packsonflight From Iceland, joined Jan 2010, 321 posts, RR: 0 Reply 160, posted (3 months 2 weeks 5 days 18 hours ago) and read 9366 times:
Quoting ComeAndGo (Reply 150): Or make it out of expandable kevlar. So when the battery blows the container just expands rather then rupture.
All the solution that require any change or modification of equipment, that needs to be re certified, like a different battery, new charger or a new or different container take a lot of time, possibly up to 6 months. So there will be no quick fix that require any change of equipment. In case Boeing can not get the 787 in the air again without doing that I would expect broader redesign of the system
The quick fix would be like Tom says that Boeing demonstrates that the aircraft is safe possibly with some changes to operating and maintainance procedures, but I guess that is unthinkable until NTSB has come up with the cause for those two battery fires
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 161, posted (3 months 2 weeks 5 days 17 hours ago) and read 9383 times:
Quoting spacecadet (Reply 159): Smaller cells spaced further apart would fix that.
What say you, engineers?
I'm not sure how that makes the NTSB happy...their current angle seems to be that it's simply unacceptable for the battery to catch fire. Having only one cell melt down, rather than all of them, has implications for containment and damage to other systems but one cell going up in smoke still kills the battery and is still a battery fire.
Quoting packsonflight (Reply 160): All the solution that require any change or modification of equipment, that needs to be re certified, like a different battery, new charger or a new or different container take a lot of time, possibly up to 6 months.
6 months would be a pretty hefty design change...with the scrutiny involved, the media circus, and the amount of people that Boeing, the FAA, EASA, JCAB, the suppliers, and the NTSB are all throwing at the problem, I would expect this one to move (properly) through the process at the head of the line.
Quote: Even before two battery failures led to the grounding of all Boeing 787 jets this month, the lithium-ion batteries used on the aircraft had experienced multiple problems that raised questions about their reliability.
Officials at All Nippon Airways, the jets’ biggest operator, said in an interview on Tuesday that it had replaced 10 of the batteries in the months before fire and smoke in two cases caused regulators around the world to ground the jets.
The airline said it told Boeing of the replacements as they occurred but was not required to report them to safety regulators because no flights were canceled. National Transportation Safety Board officials said Tuesday that the battery replacements were now part of their inquiry.
This fills in a few more blanks that have been speculated about, yes there were widespread issues with the 787 batteries, no the safety authorities were no informed and now that they kmow about it they are adding it to the investigation. The article also includes this gem
Quote: 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 that type of battery provided the most power, but could also overheat more quickly.
Shenzhen From United States of America, joined Jun 2003, 1701 posts, RR: 2 Reply 163, posted (3 months 2 weeks 5 days 16 hours ago) and read 9097 times:
Quoting BoeingVista (Reply 162): This fills in a few more blanks that have been speculated about, yes there were widespread issues with the 787 batteries, no the safety authorities were no informed and now that they kmow about it they are adding it to the investigation. The article also includes this gem
ANA having replaced 10 batteries doesn't (in my opinion) mean there is widespread issues with the 787 batteries. What it does say is that 10 batteries were replaced across xx airplanes, probably because they had a low charge. This could be caused by someone leaving the battery on, a faulty charger, a faulty battery (might just be its time) and so forth.
BoeingVista From Australia, joined Jan 2009, 1011 posts, RR: 2 Reply 164, posted (3 months 2 weeks 5 days 16 hours ago) and read 9041 times:
Quoting Shenzhen (Reply 163): ANA having replaced 10 batteries doesn't (in my opinion) mean there is widespread issues with the 787 batteries. What it does say is that 10 batteries were replaced across xx airplanes, probably because they had a low charge. This could be caused by someone leaving the battery on, a faulty charger, a faulty battery and so forth.
10 batteries and chargers were replaced over a fleet of 17 aircraft and you don't think this is significant? But of course when these batteries were beginning to be replaced ANA's fleet would have been about 5.
At least 5 replaced for a low charge condition, low charge being a known failure mode that can lead to thermal runaway? And in fact a low charge fault was reported in the 787 that DID suffer a thermal runaway and was forced to make an emergency landing. No wonder the FAA is spooked theses issues seem to be much more widespread that we imagined.
If you didn't cherry pick the article to fit your agenda is also mentions Boeing and ANA didn't report the battery changes because they were a reliability concern NOT a safety concern. If anything - it proves that the safeguards Boeing installed were highly successful with the two notable exceptions being the JL and NH birds recently.
JoeCanuck From Canada, joined Dec 2005, 4993 posts, RR: 29 Reply 166, posted (3 months 2 weeks 5 days 16 hours ago) and read 8943 times:
Quoting tdscanuck (Reply 158): In max999's defense, the suggestion got made, although I can't find the post so it's either buried somewhere or the post got deleted.
Ah...I must have missed it. Thanks. Still...the vast majority of posters seem to agree with the grounding...if little else.
Shenzhen From United States of America, joined Jun 2003, 1701 posts, RR: 2 Reply 167, posted (3 months 2 weeks 5 days 16 hours ago) and read 8912 times:
Quoting BoeingVista (Reply 164): 10 batteries and chargers were replaced over a fleet of 17 aircraft and you don't think this is significant? But of course when these batteries were beginning to be replaced ANA's fleet would have been about 5.
At least 5 replaced for a low charge condition, low charge being a known failure mode that can lead to thermal runaway? And in fact a low charge fault was reported in the 787 that DID suffer a thermal runaway and was forced to make an emergency landing. No wonder the FAA is spooked theses issues seem to be much more widespread that we imagined.
How old is the battery on a phone before they start seeing a little less performance and lower voltage. I wonder what the expected "on wing" time for a battery is today. If 12 months, then some could have been scheduled for replacement.
When a cell (inside the battery) dies and you lose 4 volts, you will see a lower voltage.
Shenzhen From United States of America, joined Jun 2003, 1701 posts, RR: 2 Reply 168, posted (3 months 2 weeks 5 days 15 hours ago) and read 8749 times:
Quoting Shenzhen (Reply 167): 10 batteries and chargers were replaced over a fleet of 17 aircraft and you don't think this is significant? But of course when these batteries were beginning to be replaced ANA's fleet would have been about 5.
At least 5 replaced for a low charge condition, low charge being a known failure mode that can lead to thermal runaway? And in fact a low charge fault was reported in the 787 that DID suffer a thermal runaway and was forced to make an emergency landing. No wonder the FAA is spooked theses issues seem to be much more widespread that we imagined.
How old is the battery on a phone before they start seeing a little less performance and lower voltage. I wonder what the expected "on wing" time for a battery is today. If 12 months, then some could have been scheduled for replacement.
When a cell (inside the battery) dies and you lose 4 volts, you will see a lower voltage.
I used google to see if the MRBR is available on the internet. It wasn't, but did find the report for the 767. For the battery, this is what is required....
24-006 24-31-01 9 RS 2000 HRS ALL ALL RESTORE THE MAIN BATTERY (OFF-AIRCRAFT).
At 2000 hours, the main battery must be removed from the airplane and overhauled/restored. If the ANA airplanes flew 10 hours a day.........
The APU battery has the same requirement.
I guess my point is that no battery stays on an airplane very long, and if there was reliability issues with the battery, one would expect an airline to modify the hours allowed on wing, within their own maintenance program, to preclude un-scheduled maintenance which can equal delays / cancellations.
The Times also ran an article on Cessna's new battery:
"A video shows what happened when engineers disabled all the battery’s protective systems, overcharged it and then deliberately ignited the hot chemicals: Nothing more than a few wisps of smoke puffed out of the battery box."
spacecadet From United States of America, joined Sep 2001, 3249 posts, RR: 14 Reply 170, posted (3 months 2 weeks 5 days 14 hours ago) and read 8600 times:
Quoting tdscanuck (Reply 161): I'm not sure how that makes the NTSB happy...their current angle seems to be that it's simply unacceptable for the battery to catch fire.
Well, let's go back to the discussion on what constitutes "fire". If you strengthen containment, improve cooling, make the cells smaller and space them further apart, then what do you have if you get thermal runaway in one cell? Let's say instead of 8 cells you have 64, so each cell is 1/8 the size of a current cell. And you design it such that the failure of any one cell will be contained, and will not affect any of the other cells. Even if one cell fails, would that result in a "fire" or simply a momentary (and small) release of thermal energy?
Quoting phxa340 (Reply 165): If anything - it proves that the safeguards Boeing installed were highly successful with the two notable exceptions being the JL and NH birds recently.
(spit-take) You're talking about 2 failures out of 24 planes in these two fleets. This is an 8.3% failure rate in the span of a week. This is not proof that safeguards were successful.
And that's discounting the other issues coming to light, which were "reliability" issues that nevertheless obviously could have (and did) become "safety" issues.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
rheinwaldner From Switzerland, joined Jan 2008, 2061 posts, RR: 6 Reply 171, posted (3 months 2 weeks 5 days 14 hours ago) and read 8616 times:
Quoting spacecadet (Reply 159):
The Verge has a sensationalist headline (obviously) but the real story here is that Elon Musk, who designs electric cars with lithium ion batteries for a living, says a simple change to more and smaller cells with more space in between would go a long way towards solving this problem. The real problem with the 787 battery, he says, is that the cells are so large and so close together than if one goes, all of them go in a domino effect due to the amount of energy contained in each cell and the ease of transferring that energy from one cell to the next. Smaller cells spaced further apart would fix that.
What say you, engineers?
I agree. I have said it many threads ago already.
Quoting tdscanuck (Reply 161): I'm not sure how that makes the NTSB happy...their current angle seems to be that it's simply unacceptable for the battery to catch fire.
That has been required right from the start and I still think it is realisticly doable.
But I also think that because of the size of a single cell, dynamic intra-cell effects could start developping, where parts of a cell start to runaway, just because its dimension is so widespread. In a sense we could no longer speak from homogenous single cells, but from independetly behaving, different zones, that are only monitored as a total....
Sounds like the existing (necessary) safe guards for the LiIo batteries are so restrictive that they render any advantages not worth the trouble in practice.
BoeingVista From Australia, joined Jan 2009, 1011 posts, RR: 2 Reply 173, posted (3 months 2 weeks 5 days 14 hours ago) and read 8638 times:
Quoting phxa340 (Reply 165): If you didn't cherry pick the article to fit your agenda is also mentions Boeing and ANA didn't report the battery changes because they were a reliability concern NOT a safety concern. If anything - it proves that the safeguards Boeing installed were highly successful with the two notable exceptions being the JL and NH birds recently.
The Seattle Times article says 100 - 150 batteries failed fleet wide, I don't see how Boeing can have 100 plus Li-ion batteries plus multiple fail knowing that failed Li-ion batteries can cause fires, on a fleet of under 50 aircraft and not consider this a safety issue. If they did not see this as a safety issue then all the better that this is now being looked at by the FAA and NTSB as it clearly DID turn out to be a safety issue.
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 174, posted (3 months 2 weeks 5 days 14 hours ago) and read 8590 times:
A lot of them havn't failed, if they just get to 15% capacity they lock themselves out, and have to be returned to the manufactuer to be reset and recharged safely. It appears that the battery demands of a plane on the ground will drain them more than anticicpated.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 175, posted (3 months 2 weeks 5 days 14 hours ago) and read 8605 times:
Quoting BoeingVista (Reply 173): I don't see how Boeing can have 100 plus Li-ion batteries plus multiple fail knowing that failed Li-ion batteries can cause fires, on a fleet of under 50 aircraft and not consider this a safety issue.
Because you have to actually read the article rather than react to its title:
-----
"Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated
...
These problems seem separate from the two more significant incidents, when a battery caught fire on the ground in Boston and another smoldered in mid-air in Japan forcing an emergency landing
...
A second source with indirect knowledge of the progam confirmed multiple battery problems.
And another source said that additional problems included batteries that had failed because airline mechanics had improperly disconnected them, which trips one of the protection features and renders the battery unusable.
Other batteries were returned because they had exceeded their expiration date, the third source said."
-----
It isn't as if 100 batteries were imminent threats to aviation safety on their own.
The battery in the video is a Lithium Iron Phosphate battery...a chemically different battery than the ones found on the 787. It reacts differently to over/under charging, over/under voltage conditions, heat and impact. What contains one type might not contain the other.
As well, the smoke came from the battery containment so there is not necessarily anything preventing electrolyte from escaping those same vents.
wjcandee From United States of America, joined Jun 2000, 4553 posts, RR: 17 Reply 177, posted (3 months 2 weeks 5 days 14 hours ago) and read 8601 times:
Quoting RickNRoll (Reply 174):
A lot of them havn't failed, if they just get to 15% capacity they lock themselves out, and have to be returned to the manufactuer to be reset and recharged safely. It appears that the battery demands of a plane on the ground will drain them more than anticicpated.
Not necessarily, given that the article says that some ran down or locked out because mechanics incorrectly disconnected them.
Sounds like this may be in part a user problem.
And sometimes the problem is so deeply ingrained in the culture of the operation that nobody notices the real cause?
Remember when they were about to ground the L1011 because numerous Eastern Air Lines flight attendants (but not passengers) were experiencing skin reddening around their necks after flights? That flight attendants were refusing to fly on the plane because of the "danger"? How the media hysterically talked about the "danger"? Does anyone besides me recall what turned out to be the problem?
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 178, posted (3 months 2 weeks 5 days 14 hours ago) and read 8603 times:
Quoting wjcandee (Reply 177): Does anyone besides me recall what turned out to be the problem?
BoeingVista From Australia, joined Jan 2009, 1011 posts, RR: 2 Reply 179, posted (3 months 2 weeks 5 days 14 hours ago) and read 8637 times:
Quoting AeroWesty (Reply 175): It isn't as if 100 batteries were imminent threats to aviation safety on their own.
At least 2 batteries clearly were, and these were not amongst the 100 returned. How many more?
You know, I believe thats some people only believe a safety threat exists once it has happened and we are standing around looking at a smoking hole in the ground.
You prevent deaths by investigating unexpected failures and if 100 failed 40kg Li-ion batteries on an aircraft doesn't ring alarm bells knowing the power that they can unleash when they go bad then you are in the wrong business.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 180, posted (3 months 2 weeks 5 days 13 hours ago) and read 8589 times:
Quoting BoeingVista (Reply 179): You prevent deaths by investigating unexpected failures and if 100 failed 40kg Li-ion batteries on an aircraft doesn't ring alarm bells knowing the power that they can unleash when they go bad then you are in the wrong business.
What would be accomplished looking for a fire threat when the reason for their return was "battery disconnected improperly" or "battery allowed to run down below spec", or "battery past expiration date"? How are those situations threats to aviation safety as standalone incidents?
7BOEING7 From United States of America, joined Oct 2012, 500 posts, RR: 3 Reply 181, posted (3 months 2 weeks 5 days 13 hours ago) and read 8604 times:
Quoting BoeingVista (Reply 179): You prevent deaths by investigating unexpected failures and if 100 failed 40kg Li-ion batteries on an aircraft doesn't ring alarm bells knowing the power that they can unleash when they go bad then you are in the wrong business.
"Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated"
Which part of this do you not understand??? Sounds like it's operator error combined with improper design specs -- expensive but not catastrophic.
JoeCanuck From Canada, joined Dec 2005, 4993 posts, RR: 29 Reply 182, posted (3 months 2 weeks 5 days 13 hours ago) and read 8568 times:
Quoting spacecadet (Reply 159): The Verge has a sensationalist headline (obviously) but the real story here is that Elon Musk, who designs electric cars with lithium ion batteries for a living, says a simple change to more and smaller cells with more space in between would go a long way towards solving this problem. The real problem with the 787 battery, he says, is that the cells are so large and so close together than if one goes, all of them go in a domino effect due to the amount of energy contained in each cell and the ease of transferring that energy from one cell to the next. Smaller cells spaced further apart would fix that.
That, if it worked, wouldn't solve the certification problem since it would have to be tested and proven as much as any other design, and probably more than going to battery types already proven in airline service. Isolating cells still doesn't prevent any single cell from catching fire which is what the FAA is looking for. They want a 0% chance of any cell catching fire...ever...which may not be achievable since any battery of any type can catch fire but there are certainly safer types than the current ones.
I think Boeing will end up biting the bullet and replacing the batteries with something more chemically benign while more exotic batteries are being further tested.
Eventually, the hope is that investigators discover exactly what caused the fires, and that the causes were the same for both batteries, solutions identified, (including more robust containment), and this is one more problem permanently checked off of the 787 to-do list.
I still think permanent fixes will take longer than putting an interim solution in place and getting the planes flying.
XT6Wagon From United States of America, joined Feb 2007, 3129 posts, RR: 4 Reply 183, posted (3 months 2 weeks 5 days 13 hours ago) and read 8491 times:
Quoting BoeingVista (Reply 179):
At least 2 batteries clearly were, and these were not amongst the 100 returned. How many more?
and how many seat covers have been replaced in that time? ok thats a little silly..... so lets go for
How many tires? How many brakes?
Some things are "wear" items even if you don't think of them that way. Batteries are wear items. They wear out when used. They wear out when not used. ALL batteries mankind uses are this way. Well atleast all the ones worth using.
astuteman From United Kingdom, joined Jan 2005, 9135 posts, RR: 96 Reply 184, posted (3 months 2 weeks 5 days 13 hours ago) and read 8466 times:
Quoting phxa340 (Reply 165): If you didn't cherry pick the article to fit your agenda is also mentions Boeing and ANA didn't report the battery changes because they were a reliability concern NOT a safety concern. If anything - it proves that the safeguards Boeing installed were highly successful
Either that or it proves that ANA were not aware of the underlying safety issue...
Quoting 7BOEING7 (Reply 181): Which part of this do you not understand??? Sounds like it's operator error combined with improper design specs -- expensive but not catastrophic.
In terms of the way a complex system fails, operator error combined with improper design specs could easily have the potential to be catastrophic IF the particular type of Li battery being used is one that is particularly prone to overheating problems under certain conditions, as LiCo batteries appear to be
Quoting BoeingVista (Reply 162): 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 that type of battery provided the most power, but could also overheat more quickly.
For me failures like this tend to have multiple causes, and the key will be to understand which parts of the "system" need to change
Quoting JoeCanuck (Reply 176): The battery in the video is a Lithium Iron Phosphate battery...a chemically different battery than the ones found on the 787. It reacts differently to over/under charging, over/under voltage conditions, heat and impact. What contains one type might not contain the other.
I'm not sure how well recognised it is that there is more than one type of li ion battery.
I'm not sure how easy it would be to change the 787's batteries to Li Iron Phosphate, or whether that could contribute to a solution. But if it is more benign under "operator error or improper design spec" it might form part of a solution..
FlyingAY From Finland, joined Jun 2007, 640 posts, RR: 0 Reply 185, posted (3 months 2 weeks 5 days 13 hours ago) and read 8438 times:
Quoting 7BOEING7 (Reply 181): "Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated"
Which part of this do you not understand??? Sounds like it's operator error combined with improper design specs -- expensive but not catastrophic.
Considering the nature of a LiIon battery, I think the system should automatically try to prevent a situation where the battery gets too empty and must be replaced. Charge the battery automatically as needed, raise an alarm if the capacity gets low and cut off the power before a critically low charge is reached.
Are these replaced batteries all main batteries? I've understood the APU battery should see only a very limited amount of use. Why would they be run down so far that a low-voltage cutout gets activated? Remember that self discharge of LiIon is very small (just installed a battery manufactured 1,5 years ago that had more than 50% of the capacity left).
Quoting SeattleTimes: Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated.
At that stage, the batteries, which cost about $16,000 each, are essentially dead and cannot be recharged.
If most of the batteries had run down so far that the batteries are dead, why is there no mechanism that cuts the power before the battery is dead? It would seem like bad design to let the battery discharge that far that it is rendered unusable. Imagine having your cell phone battery changed everytime you forget to charge it before the battery is empty! This is most likely simplifying the thing too much, but so many battery failures on such a small fleet sounds suspicious. I'm sure we'll hear more in the nearby future.
seahawk From Germany, joined May 2005, 97 posts, RR: 0 Reply 186, posted (3 months 2 weeks 5 days 13 hours ago) and read 8361 times:
I would say it is not uncommon for a new technology to have some problems at the start. Although I must say it would have been interesting to know if Boeing had to report battery changes to the FAA during the test flight phase and if there have been any problems during that phase. If not it would point into the direction of user error by the airlines. I would also believe that those reported 100-150 battery changes were unscheduled changes, otherwise it would be a joke to even talk about them.
All involved parties must come clean quickly now, before the reputation of the Dreamliner, FAA and Boeing is damaged. The information management must improve. They need to put all battery system related problems (safety or reliability or whatever) on the table now.
flood From United States of America, joined Feb 2009, 1052 posts, RR: 1 Reply 187, posted (3 months 2 weeks 5 days 13 hours ago) and read 8365 times:
Quoting JoeCanuck (Reply 176): The battery in the video is a Lithium Iron Phosphate battery...a chemically different battery than the ones found on the 787. It reacts differently to over/under charging, over/under voltage conditions, heat and impact. What contains one type might not contain the other.
Yes, I should have been more descriptive, sorry. If I'm not mistaken the 787's batteries are cobalt-based whereas the A350's Saft battery is manganese. I just found the containment interesting and, in light of the previous comments surrounding armoring, wonder if such a design can't be upscaled to provide a better venting/containment solution for the 787's units.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 188, posted (3 months 2 weeks 5 days 12 hours ago) and read 8248 times:
Quoting phxa340 (Reply 165): If you didn't cherry pick the article to fit your agenda is also mentions Boeing and ANA didn't report the battery changes because they were a reliability concern NOT a safety concern.
then why is this happening ?
Quoting BoeingVista (Reply 162): National Transportation Safety Board officials said Tuesday that the battery replacements were now part of their inquiry.
Well, it could be that at the time when the batteries were changed it was not a safety concern. In the light of current events it very well could cause some concern.
AirlineCritic From Finland, joined Mar 2009, 611 posts, RR: 1 Reply 190, posted (3 months 2 weeks 5 days 12 hours ago) and read 8074 times:
The report about large number of batteries being returned is interesting. (If true, as always.)
Remember that the 787 had a very extensive flight testing program. Why are the battery problems coming up now, and not during flight testing? One theory is that operational practices and airport facilities are different. If I were Boeing, I would investigate the history behind each case. Not that I believe the returned batteries were about to burn - probably not. But it does seem like a high frequency of component maintenance events. Something is causing this. Maybe an operational error is causing batteries to work not optimally, and in some small percentage, even lead to batteries suffering so much that they have a risk of thermal run away. At least that would be an angle to look at.
ComeAndGo From United States of America, joined Mar 2005, 950 posts, RR: 0 Reply 191, posted (3 months 2 weeks 5 days 11 hours ago) and read 8017 times:
it's very simple it's mentioned in the Seattle Times article. This battery will drain in less then one hour if used by ramp personal when servicing the aircraft with it's power off. So refueling or loading/unloading cargo from the aircraft. When the main aircraft power is off the battery supplies electricity for lights and other ramp related systems that ground personal will use to service the aircraft. Apparently this battery design allows for the battery to discharge in less than an hour with only minimal draw.
art From Lebanon, joined Feb 2005, 2937 posts, RR: 0 Reply 192, posted (3 months 2 weeks 5 days 11 hours ago) and read 8051 times:
The lithium ion batteries installed on the Boeing 787 are inherently unsafe, says Elon Musk, founder of SpaceX and owner of electric car maker Tesla.
"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," writes Musk in an email to Flightglobal.
"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," he adds.
Both Boeing and Tesla use batteries fueled by lithium cobalt oxide, which is among the most energy-dense and flammable chemistries of lithium-ion batteries on the market. While Boeing elected to use a battery with a grouping of eight large cells, Tesla's batteries contain thousands of smaller cells that are independently separated to prevent fire in a single cell from harming the surrounding ones.
If this was above predicted wear and replacement this should also be investigated.
Quoting AeroWesty (Reply 180):
What would be accomplished looking for a fire threat when the reason for their return was "battery disconnected improperly" or "battery allowed to run down below spec", or "battery past expiration date"? How are those situations threats to aviation safety as standalone incidents?
Because under voltage conditions can be the precursor of thermal runaway. Li-ion batteries are clearly a fire threat you don't seem to accept the obvious.
This might be a good time to point out that the FAA has not rulled out under voltage as a cause of the 2 battery meltdown incidents.
Quoting astuteman (Reply 184): For me failures like this tend to have multiple causes, and the key will be to understand which parts of the "system" need to change
Lord, a sensible response.. Yes, if you see a whole bunch of unpredicted failures you need to investigate without preconceptions and find the cause which could be anywhere in the system.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 194, posted (3 months 2 weeks 5 days 11 hours ago) and read 7929 times:
Quoting BoeingVista (Reply 193): Because under voltage conditions can be the precursor of thermal runaway. Li-ion batteries are clearly a fire threat you don't seem to accept the obvious.
Perhaps you can explain the obvious I'm missing then.
I accept that once a battery falls below a certain threshold while it's powering aircraft systems in lieu of another power source, the system renders it unusable. It gets replaced. It does not fly.
Correct me if I'm wrong, but what you seem to be suggesting is that if a battery would fall below this certain threshold during flight, the safety systems would allow the battery to be recharged, causing a thermal runaway. That's certainly a possibility which should be reviewed, I've no problem with that.
However, in my non-expert mind, I do believe that that scenario would be one expected, tested for, and safeties built around, so that a battery falling below spec while the other generators are idle wouldn't necessarily be viewed as an imminent threat to aviation safety as a standalone event.
JerseyFlyer From United Kingdom, joined May 2007, 458 posts, RR: 0 Reply 196, posted (3 months 2 weeks 5 days 11 hours ago) and read 7876 times:
Quoting art (Reply 192): While Boeing elected to use a battery with a grouping of eight large cells, Tesla's batteries contain thousands of smaller cells that are independently separated to prevent fire in a single cell from harming the surrounding ones.
Intuitively this makes sense. An explanation from Boeing for their choice of eight large cells when presumably they discounted options comprising larger numbers of smaller cells would be of interest.
sankaps From United States of America, joined Jan 2008, 1256 posts, RR: 0 Reply 197, posted (3 months 2 weeks 5 days 11 hours ago) and read 7815 times:
Quoting tdscanuck (Reply 149): Sure they can. For example:
"As a result of an in-flight, Boeing 787 battery incident earlier today in Japan, the FAA will issue an emergency airworthiness directive (AD) to address a potential battery fire risk in the 787 and require operators to temporarily cease operations.
The AD was to ground the aircraft. That is, as I said, the only logical option they have if they do not know the root cause of a recurring failure with potentially serious safety implications.
Quoting tdscanuck (Reply 149): They had lots of choices...the AD could have imposed an operating limitation like "inspect the battery after every flight" or something like that.
That would be a fairly pointless AD since there is no evidence that we know of yet, that suggests inpsections after every flight would help.
The FAA did the right thing here, there really was no other acceptable option short of waiting to act until something catastrophic happened. And that, in today's safety climate, would simply be highly, perhaps even criminally negligent.
BoeingVista From Australia, joined Jan 2009, 1011 posts, RR: 2 Reply 198, posted (3 months 2 weeks 5 days 11 hours ago) and read 7743 times:
Quoting AeroWesty (Reply 194): Correct me if I'm wrong, but what you seem to be suggesting is that if a battery would fall below this certain threshold during flight, the safety systems would allow the battery to be recharged, causing a thermal runaway. That's certainly a possibility which should be reviewed, I've no problem with that.
Over discharge of a Li-ion battery can lead to it short circuiting and that can lead to thermal runaway, it does not need to be recharged to be potentially dangerous.
So under voltage can be as dangerous as over voltage.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 199, posted (3 months 2 weeks 5 days 10 hours ago) and read 7650 times:
Quoting BoeingVista (Reply 198): Over discharge of a Li-ion battery can lead to it short circuiting and that can lead to thermal runaway, it does not need to be recharged to be potentially dangerous.
When you say "over discharge", is your meaning discharging too quickly or discharging below a certain value, or both?
RickNRoll From Afghanistan, joined Jan 2012, 475 posts, RR: 0 Reply 200, posted (3 months 2 weeks 5 days 10 hours ago) and read 7539 times:
Quoting wjcandee (Reply 177): Not necessarily, given that the article says that some ran down or locked out because mechanics incorrectly disconnected them.
Sounds like this may be in part a user problem.
A normal battery doesn't need that special handling. A normal battery doesn't need to be returned to the manufacturer if it goes flat. These batteries need this special handling for safety reasons, but is it worth the trouble. Once again, I think the A350 team will have more to chew on.
sebolino From France, joined May 2001, 3667 posts, RR: 5 Reply 201, posted (3 months 2 weeks 5 days 10 hours ago) and read 7574 times:
Quoting DocLightning (Reply 6): Quoting liftsifter (Reply 2):
Has John Leahy made a comment at all about the grounding and how it may affect the A350 program?
Even Mr. Leahy is smart enough to know to keep his mouth shut.
"Even Mr. Leahy" ? You think he's an idiot ?
Quoting AirlineCritic (Reply 7): And you can rest assured that none of them are gloating about it, because they know that if they are not careful, their new A350 might be next.
ncfc99 From United Kingdom, joined May 2005, 643 posts, RR: 0 Reply 202, posted (3 months 2 weeks 5 days 9 hours ago) and read 7417 times:
Quoting BoeingVista (Reply 173): Quoting phxa340 (Reply 165):If you didn't cherry pick the article to fit your agenda is also mentions Boeing and ANA didn't report the battery changes because they were a reliability concern NOT a safety concern. If anything - it proves that the safeguards Boeing installed were highly successful with the two notable exceptions being the JL and NH birds recently.
The Seattle Times article says 100 - 150 batteries failed fleet wide, I don't see how Boeing can have 100 plus Li-ion batteries plus multiple fail knowing that failed Li-ion batteries can cause fires, on a fleet of under 50 aircraft and not consider this a safety issue. If they did not see this as a safety issue then all the better that this is now being looked at by the FAA and NTSB as it clearly DID turn out to be a safety issue.
I'm with Boeingvista on this, Boeing and ANA may have thought it to be a reliability issue, I can live with that, but with the 2 major battery incidents, its become a safety issue which the FAA has taken out of Boeings hands.
Quoting RickNRoll (Reply 174): A lot of them havn't failed, if they just get to 15% capacity they lock themselves out, and have to be returned to the manufactuer to be reset and recharged safely. It appears that the battery demands of a plane on the ground will drain them more than anticicpated.
If they are getting to that 15% of charge regularly and having to be replaced, something needs to be addressed to make it a rare occurance rather than a regular one. Same goes if they are needing to be replaced due to operator error when disconecting. Maybe i'm oversimplyfying my thoughts, I don't work in the industry, but it seems to me long term, replacing batteries on a regular basis due to these issues needs to be engineered out. Does the battery being drained to about 16-20% charge on a regular basis have any affect on it? (i.e just above the cut off point)
Quoting AeroWesty (Reply 180): Quoting BoeingVista (Reply 179):You prevent deaths by investigating unexpected failures and if 100 failed 40kg Li-ion batteries on an aircraft doesn't ring alarm bells knowing the power that they can unleash when they go bad then you are in the wrong business.What would be accomplished looking for a fire threat when the reason for their return was "battery disconnected improperly" or "battery allowed to run down below spec", or "battery past expiration date"? How are those situations threats to aviation safety as standalone incidents?
Those incidents may not be threats to aviaton as standalone incidents, but put them altogether with the 2 major incidents and they become something that needs to be looked into. 100-150 battery failures/cut offs/operator errors on a fleet of 60-70 aircraft seems alot me. Does anyone know how long the batteries are supposed to be in use for before removal and overhaul?
Quoting 7BOEING7 (Reply 181): "Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated"Which part of this do you not understand??? Sounds like it's operator error combined with improper design specs -- expensive but not catastrophic.
Your post come across as dismissive of the returned batteries being important in the investigation. Low voltage is one of the causes of thermal runaway as far as I have learnt on these threads. If batteries are being returned on a regular basis because they have cut off by the low voltage, and then we had 2 major incidents of thermal runaway, returned batteries for this reason very much become important. You have said it sounds like operator error or improper design spec, it also sounds like it could be a problem in how the plane is using the batteries, in that it drains them to the cut off point on a regular basis. Weather it is a deisgn problem that needs to be fixed or a process issue that nees to be changed is what needs to be established. In the long run airlines won't put up with it I wouldn't have thought.
rheinwaldner From Switzerland, joined Jan 2008, 2061 posts, RR: 6 Reply 203, posted (3 months 2 weeks 5 days 9 hours ago) and read 7379 times:
Quoting 7BOEING7 (Reply 181): Quoting BoeingVista (Reply 179):
You prevent deaths by investigating unexpected failures and if 100 failed 40kg Li-ion batteries on an aircraft doesn't ring alarm bells knowing the power that they can unleash when they go bad then you are in the wrong business.
"Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated"
This information is a hint that the BMS is designed wrongly. If a large number of batteries is killed by discharging them too much, the charging/discharging system is not worth much. It is the chargers responsibility to always maintain safe upper and lower voltage limit over any cell. There is no other responsibility for ruined batteries by the hundreds than crappy chargers.
If the low voltage condition is not handled properly by the BMS, undetected damages to cells will be inevitable which make the charging and further use of the battery unpredictable. A single damaged cell might strike back the next time a charge run is made.
Even RC modellers have enormous low voltage detection gear to never unload the battery below certain limits. The considered accuracy goes down to millivolts...
Quoting JoeCanuck (Reply 182): That, if it worked, wouldn't solve the certification problem since it would have to be tested and proven as much as any other design, and probably more than going to battery types already proven in airline service.
Do you think there will be a solution without any certification problem? I expect huge certification efforts at this point. Regardless of the solution, that will be chosen.
Quoting JoeCanuck (Reply 182): Isolating cells still doesn't prevent any single cell from catching fire which is what the FAA is looking for. They want a 0% chance of any cell catching fire...ever...which may not be achievable since any battery of any type can catch fire but there are certainly safer types than the current ones.
The main point Elon Musk has raised are the small number of large cells. A larger number of smaller cells can be operated safely even in close proximity. The aspect that is unique on the 787 are the large cells and not the tight cell layout.
Quoting seahawk (Reply 186): I would say it is not uncommon for a new technology to have some problems at the start.
The dimension of the problem is uncommon. Including the grounding verdict.
Quoting JerseyFlyer (Reply 196): Intuitively this makes sense. An explanation from Boeing for their choice of eight large cells when presumably they discounted options comprising larger numbers of smaller cells would be of interest.
I agree.
Quoting BoeingVista (Reply 198): Over discharge of a Li-ion battery can lead to it short circuiting and that can lead to thermal runaway, it does not need to be recharged to be potentially dangerous.
So under voltage can be as dangerous as over voltage.
Absolutely.
Quoting AeroWesty (Reply 199): When you say "over discharge", is your meaning discharging too quickly or discharging below a certain value, or both?
Both.
Below a certain voltage the cells simply will be destroyed and never useable again to store any meaningfull capacity.
And second, batteries have a C-value which is defined as follows: current that discharges the battery in one hour divided by the max. discharging current. This tells us how quick a battery may be discharged. E.g. 20C means that I might draw as much current, that after 60 minutes / 20 it (= 3 Minutes) it would become empty.
UALWN From Andorra, joined Jun 2009, 2320 posts, RR: 2 Reply 204, posted (3 months 2 weeks 5 days 9 hours ago) and read 7241 times:
Quoting 7BOEING7 (Reply 181): "Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated"
The article also says that "The frequency of battery failures reflects issues with the design of the electrical system around the battery, said the person on the 787 program."
keegd76 From UK - Northern Ireland, joined Aug 2009, 83 posts, RR: 0 Reply 205, posted (3 months 2 weeks 5 days 8 hours ago) and read 7060 times:
Just for clarification, what is the battery in question being used to power? I thought I read earlier that it was a back-up supply for the cockpit instruments. If true then that suggests it isn't being called on very often (i.e. drained). However if, as someone pointed out, the battery is used to power systems while the plane is inactive on the ground then it begs the question, shouldn't the plane hooked up to ground power when its on the ground?
Apologies if this has been done to death already.
Nothing comes down faster than a VTOL aircraft upside down.
AeroWesty From United States of America, joined Oct 2004, 18807 posts, RR: 64 Reply 206, posted (3 months 2 weeks 5 days 8 hours ago) and read 7032 times:
Quoting ncfc99 (Reply 202): Those incidents may not be threats to aviaton as standalone incidents, but put them altogether with the 2 major incidents and they become something that needs to be looked into.
I don't see where I've ever denied that. BoeingVista still hasn't made his case for why these singular incidents of batteries running down while the other generators were idle somehow presented an imminent threat to aviation safety, other than saying that people are "missing the obvious", without stating what that "obvious" is. He needs to state that in clear terms, without playing '20 questions', so his argument can be looked at and evaluated. Wouldn't you agree?
Quoting rheinwaldner (Reply 203): Below a certain voltage the cells simply will be destroyed and never useable again to store any meaningfull capacity.
Great. Understood already. Was that happening in flight other than on the ANA incident where the emergency landing was made? My understanding was that was happening on the ground, with those batteries pulled. Correct me at any point you'd like. I'm truly trying to understand why folks keep saying that these singular incidents regarding replaceable parts presented a problem as they occurred.
Quoting sweair (Reply 8): If a battery or charging system fault can be identified and a slightly enhanced containment put into place, the plane should fly in 4-6 months, if not sooner, at least as a temporary measure for current frames.
4-6 Months? If you seriously believe that, it's time to short Boeing stock. They gotta get this thing flying a lot sooner than that.
BoeingVista From Australia, joined Jan 2009, 1011 posts, RR: 2 Reply 208, posted (3 months 2 weeks 5 days 7 hours ago) and read 6815 times:
Quoting AeroWesty (Reply 206):
I don't see where I've ever denied that. BoeingVista still hasn't made his case for why these singular incidents of batteries running down while the other generators were idle somehow presented an imminent threat to aviation safety, other than saying that people are "missing the obvious", without stating what that "obvious" is. He needs to state that in clear terms, without playing '20 questions', so his argument can be looked at and evaluated. Wouldn't you agree?
I did and you replied to it.
Quoting BoeingVista (Reply 198): Over discharge of a Li-ion battery can lead to it short circuiting and that can lead to thermal runaway, it does not need to be recharged to be potentially dangerous.
So under voltage can be as dangerous as over voltage.
The batteries run down until they get to a damaged state ie, need replacement.
A battery that has rundown into an under volt condition is potentially at risk from a thermal runaway meltdown what ever the state of the generators.
By over discharge this may mean to much power drained, under volt, or discharged too quickly
It should be obvious by thread 6 that Li-ion batteries are potentially dangerous and any pattern of major faults is worth investigating.
100-150 failed batteries and multiple failed chargers is surely a symptom of wider issues with the 787's electrical system, and really should have prompted Boeing to do something but it didn't do anything that we know about apart from keep issuing replacement batteries; after 150 incidents I would suggest they cease to be singular events and become a pattern.
The NTSB agree that these failed batteries are something that needs investigating and have added it to their investigation having been belatedly informed of this by Boeing.
The NTSB have not ruled out an under volt condition as being the source of either battery meltdown.
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