A press release detailing 787 battery solutions outlined in Boeing’s Thursday’s Tokyo press conference is here.
Press coverage from last night’s briefing:
Boeing says flights could resume in weeks, not months; Japan’s regulators not so sure.
Boeing says 787 safest airplane, could fly in weeks.
LOT seeks compensation.
Fix proceeds without knowing root cause.
Boeing in strong defense of Dreamliners.
Comprehensive battery solution.
Boeing today held a special question-and-answer session follow-up to the Tokyo press conference. Ron Hinderberger, Vice President, 787-8 Engineering, Boeing Commercial Airplanes, is the representative. A running synopsis:
The FAA recently approved certification plan, part of a comprehensive process that is an important milestone. The FAA has approved the changes and we will have a series of ground and flight tests and a series of analyses to lead to certifying the airplane.
[Recaps the changes described at the Tokyo press conference.]
- The enclosure material is made of stainless steel. It does not have a dedicated cooling system. Found during testing of the battery that the battery was actually operating in temperatures that were less than originally thought when designed. One test we will do to put the battery in the enclosure and conduct tests to demonstrate appropriate temperature margins.
- Q: Japan’s equivalent of the FAA says it is inappropriate to suggest a timeline and the FAA says it will go slow. How does Boeing’s suggestion the planes will return to flight within weeks? A: The plan went through three detailed, line-by-line review with the FAA and the conclusion was that this is indeed sufficient to meet certification requirements. The reason we are confident of plan with one flight test is we are confident with detail laboratory testing with greater detail and monitoring than we could on the airplane. As you’re aware we like to operate our test teams to a plan. Three tests are completed. More testing underway and hope to have the flight test within a week or two, when all data will be sent to FAA for review. It is inappropriate for me to suggest a timeline. That said, the FAA has been involved along the way.
- Water condensation, in our effort to examine all root causes, was one of a number of simulated failure conditions to emulate the failure in the cells. This was one of the ways a short circuit could happen. Simulation did create a short that led to venting. But it is inappropriate at this time to speculate that this is the probable cause. If this proves to be the case, the drain holes and insulation between the cells will prevent it again.
- The battery blue case sits inside the enclosure case. The venting tube is titanium. Diameter is 1 inch. Steel box is 1.25 inches thick. The battery envelope has not changed. The venting tube goes to a new hole in the fuselage, but doesn’t require new certification requirements except to show the vapors don’t get re-ingested into the airplane, which is validated by lab testing. Testing we’re doing will be re-run for certification process but this testing has been going on for weeks in preparation for defining the end solution for the airplane.
- Batteries that are in service, we have a record, we know how each battery and cells behaved when originally manufactured. We know today which cells would not pass the battery test. When they come back these cells will be automatically rejected. The batteries will then be refurbished.
- [More recap from Tokyo press conference.]
- The containment box is air tight, a sealed container.
- 150 pound weight increase is aggregate for the two batteries. Retaining the lithium-ion battery is a result of a number of trades in selecting it to begin with and those remain valid today. (Highly paraphrased.)
- Not aware of any history of Boeing previously considered a containment box, nor of anyone in automotive history or elsewhere that would have suggested a containment box.
- Q: You have explicitly and implicitly challenged NTSB findings on thermal runaway and other conclusions. A: I don’t know that we would characterize the seriousness of events differently. The NTSB has a different view of thermal runaway than we do. Our view of seriousness of this incident is demonstrated by the thousands and thousands of hours we’ve put in and the people drawn from the Boeing Enterprise and from outside Boeing.
- ZA005 and Line 86: one airplane will do wheels-up flight test, the other an on-airplane ground test. ZA005 will be the ground-test airplane.
- With these changes we think the likelihood of a repeat is very unlikely, more in line with what we intended. With that said I can’t say we will never have a failure. (Echoes Mike Sinnett from the Tokyo press conference: “parts fail”)
- RTCA commission generated lithium-ion set of requirement after original work containing 104 requirements in the document. Some went beyond requirements established in the special condition. As a result of this change, we have elected to certify this change to go beyond special conditions and reach into DO-311. In working with FAA we determined it would be best to go with changes in DO-311. The most significant change is the venting should be able to accommodate the venting of all eight cells simultaneously. This is three times what has been required.
Round two- ‘ forget what we told you- now we are telling you ” – poor paraphrase from ” Mr Roberts “
Well, his boss apparently believes it’s “appropriate” to suggest a timeline of “weeks”, and not months.
drain holes again- if there is insulation between cells and all around, how does condensation on top of battery get to drain holes ? and if it does, then where do drain holes go ?
maybe we install batteries upside down ? Or fly inverted ? Or soak it up with pampers or silicone gel packs ?
Drain holes in the bottom frame of the battery.
If the box is hermetic until the “seal is broken” no moisture should be able to collect.
But that would require the box to be at ground altitude all the time.
This again would keep pressure cycles away from the cells.
Due to the fact that hot air is lighter than cool air, condensation will first occur on the bottom. Condensation will also only happen then inside temperature of battery is lower than temperature of avionics bay. A battery can only stay cool without charge or discharge. I doubt that there is any problem with humidity inside an avionics bay.
Quoting from the “questions and answers” of Boeing’s presentation in Japan:
“•Water condensation, in our effort to examine all root causes, was one of a number of simulated failure conditions to emulate the failure in the cells. This was one of the ways a short circuit could happen. Simulation did create a short that led to venting. But it is inappropriate at this time to speculate that this is the probable cause. If this proves to be the case, the drain holes and insulation between the cells will prevent it again.
•The battery blue case sits inside the enclosure case. The venting tube is titanium. Diameter is 1 inch. Steel box is 1.25 inches thick. The battery envelope has not changed. The venting tube goes to a new hole in the fuselage, but doesn’t require new certification requirements except to show the vapors don’t get re-ingested into the airplane, which is validated by lab testing. Testing we’re doing will be re-run for certification process but this testing has been going on for weeks in preparation for defining the end solution for the airplane.”
I am unable to understand the “water condensation…” statement above, including “…This was one of the ways a short circuit could happen” Does this imply that if a cell is standing in a tiny puddle of water — formed by condensation of moisture within the battery box — such a cell is not sufficiently sealed up to prevent the entry of water into the cell?
As for the venting tube, I presume the blowout membrane designed to be ruptured only in the event of excessive pressure within the tube is located at the surface of the aircraft’s belly so it will not affect the flow of air over it during flight. However, in the event of such a blowout to vent the battery gases, will the air flowing past it resonate loudly within the tube as if in a pipe organ? Will the passengers then be inclined to accompany the pipe’s music by singing that famous hymn “Nearer my God to thee…”?
Each cell body ( made from stainless steel ) is isolated from the active internals and electrodes sticking out of the cell but floats on a voltage ~2/5th between anode and cathode ( electrode potential of stainless in relation to the other involved metals.).
If you tie the case to some other voltage you will see electrolysis inside the cell. problems abound.;-)
If you add water via condensation into the interstice between
cell bodies or cell body and the busbars or cell body and the battery case you “tie the case of a cell to some other voltage”.
In pure Heisenberg’s Uncertainty Principle style we have now the Boeing Quantum: a baterry in a box that may or may not be burning at the same time
I like it 😉
Maybe they should put a cat in the box, just to complete the quantum aspects :-).
In other news the existence of the Higgs Boson got further proof.
So we now have the Higgs Boson and the Boeing Bozons ?
Looking more and more like my suspicions about condensation immediately after the incidents could be well-founded. Cold battery in flight = condensation on ground.
But like I said on the last thread: if that was a problem before then surely atmospheric moisture is still going to evaporate & condense inside the enclosure?! The only difference being that it will pool at the bottom of the enclosure instead of at the bottom of the battery.
If there was electrical contact between cell casings, then maybe that’s an improvement. If there was “rain” from the plastic cover onto the exposed cell connector bars… then this changes nothing!
Oh yeah – so they got a short and venting without overcharging… Thought that couldn’t happen. Oh no, silly me! That falls outside their carefully chosen definition of thermal runaway. 😉
Condensation collecting on the massive cells and running down into the plastic tray underneath?
The cell bodies are on a funny floating voltage level between anode and cathode ( ref: somewhere in the NTSB report ) and
you may not tie them to another potential.
If the cells stood in a “footbath” strange effects are expectable.
My eye was on conductive path between anode/cathode and the cell body.
Any kind of unplanned conductive path inside the battery will alter the charge state for individual cells.
Boston incident was on January 7th and in Japan it was also quite cold. Therefore I doubt a condensation problem in winter time. For both cases temperature within battery was at no time colder than the avionics bay.
Actually- cold surfaces in hot air are the prime reasons for condensation .. thats why air conditioners have drains
The Japanese regulator sounds unimpressed about being told how long they are to take to certify this. 🙂
Boeing has been in a full-court press to force regulators to return the 787 to flight status. And it is possible that lobbying may be succeeding. But the Japanese remarks (I realize I am reading a translation, which may lack nuances) seem to be pressing back. The 787 was grounded in Japan before FAA took action. What I think I am reading between the lines is that Japan may not follow the FAA lead on this. The gentlemen’s agreement may be breaking down. Trust is key. Is it still there or has the FAA cozy relationship with Boeing (especially the press conference in Boston) done irreparable harm? The long term consequences for Boeing, AirBus, Bombardier, Embraer, etc should give pause. If every manufacturer must meet the requirements of multiple regulatory agencies the cost will soar. Boeing may win this battle, but they may be losing future battles because of their own short-sightedness.
What happens if the Dreamliner goes back into service in “weeks”, and a few months from now there is an incident? It will not matter whether the plane is at fault or not. The result will be disastrous for the model, and possibly for the industry. It seems to me, that if Boeing management had thought this through, a go-slow approach, cooperating with all concerned regulators, especially in public, would be the desirable course. It may be that Boeing doesn’t have that luxury. As the daily losses add up, the 787 program is probably dangerously close to the shoals of becoming a loss-forward program. Desperation may be driving a Boeing management course that seems unreasonable to outside viewers.
The damage was done in years of close “cooperation”. What we see today is exposure of that damage effected.
Agreed, this looks like a panicked organisation operating under the mantra: Failure to get the aircraft recertified ASAP is not an option!
It’s an interesting point about the auto-ratification of each-others’ certification decisions.
I would hope that even if the Japanese (and maybe EASA) require further measures than the FAA before allowing full 787 service again that that it doesn’t severely impact certification of other types from now on.
I think the move in concepts from a ‘containment’ that keeps a fire at bay to an ‘enclosure’ that suppresses fire may do the trick.
If they fire a frozen chicken at an engine, can a raccoon escape from the battery box?
Meaningless test, since you wouldn’t be allowed to set the raccoon on fire, unless the flames are no more than 2cm, in which case it’s not a fire.
Okay, those to comments made me grin. Just a tiny bit. 😀
see R.A.Heinleins “The Cat Who Walks Through Walls”
adapting that Schroedinger’s cats motive:
Only if you are daft enough to open the box will the battery burn ( or not ).
“The battery was not burning”
“There was no fire”
“There was no smoke”
“There was no such thing as thermal runaway”
– But would the FAA ever contemplate certification of a system which – in a worst case scenario involving a battery fire – ultimately depends on containing a blaze onboard an aircraft? The answer, as we now know, is that the FAA will not have to make that decision because the box, or enclosure, is designed to prevent a fire rather than ‘contain’ it.
– The bottom line is the enclosure appears to provide not only the ultimate safeguard should a failure occur, but also an additional active means of preventing one in the first place.
– What seems to speak volumes about Boeing’s confidence in the redesign is the fact that just one test flight is currently deemed sufficient to verify the improvements.
– The ultimate irony in this elaborate fix is the 150 lb of the hefty enclosure eliminates much of the weight benefit of using lithium ion batteries in the first place.
NTSB seems to have left Boeing’s boat for saver ground:
and note the infamy, they are using the F word 😉
Well, if the charcoal is hot enough you can barbecue without flames!
Boeing’s philosophy is apparently to keep digging once they’re in a hole. Can’t blame them, on the 787 that has worked well until now.
Sorry to ask this question but… Why is there so much electrical and thermal isolation in Boeing proposal if the solution avoid all fire risk?
Just tell me if i read that well « Boeing is redesigning its batteries to ensure a fire isn’t possible. Among the new features will be a fire-resistant stainless steel case that will prevent oxygen from reaching the cells so fire can’t erupt, Sinnett said. »
– first i read « fire is impossible »
– secondly i read « fire is possible if oxygen reach the celles »
Which of these two affirmations must i believe ?
I couldn’t help laughing out loud when I read that.
Why do they need a “fire-resistant stainless steel case” to keep oxygen from the cells? Wouldn’t a 5 lb evacuated rubber casing also do the trick?
How can any honest engineer have the nerve to try and sell such nonsense to the public?
In fairness, that’s in line with their design philosophy. i) design so it doesn;t fail and ii) then presume that it does and prevent that from being a problem.
granted it is supposed to be BA design Philosophy- but IF so, and IF used, why didn’t it work before ?
Why did they NOT test charger with battery ? Cuz the first time- they burnt down a building ?
When on the ground – where battery is used- the batterey goes bonkers- but battery is needed to run fans and start the apu – and why did they put battery monitor in same box as battery
And still claim the ONLY possible way to damage battery is via overcharging- which has NOT ever happened ?
I’m not saying they’re applying their philosophy. 🙂
may be of interest to some
Ion Batteries Hazard
Celina Mikolajczak, PE
Michael Kahn, PhD
Kevin White, PhD
Richard Thomas Long, PE
Exponent Failure Analysis Associates, Inc.
Fire Protection Research Foundation
Chapter 4: Lithium-Ion Battery Failures 46
Cell and Battery Failure Modes 47
Non-Energetic Failures 47
Energetic Failures: Thermal Runaway 48
Root Causes of Energetic Cell and Battery Failures 55
Thermal Abuse 56
Mechanical Abuse 57
Electrical Abuse 60
Poor Cell Electrochemical Design 63
Internal Cell Fault Related
to Manufacturing Defects 63
Factors that Influence th
e Effect of Failure 69
Cell Chemistry 69
State of Charge 70
Heat Transfer Environment 71
Thanks, Don. Very interesting — I saved the file and have started to digest some of this, but it will take time. I see my IEEE had some input, too.
But Now I need to get busy working on my income tax.
They discovered 80 things that could go wrong with the battery. Now there is something that gives you confidence in the certification process. That statement, alone, begs a lot of questions.