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Design review for 787 and “Plan B” for A350 XWB triggered by Lithium ion batteries

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Design review for 787 and “Plan B” for A350 XWB triggered by Lithium ion batteries

Old 16th Feb 2013, 16:03
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Angry Design review for 787 and “Plan B” for A350 XWB triggered by Lithium ion batteries

The objective in this thread is to discuss the implications of the design reviews and specially the “timing consequences”.

After 2012 considered the safest year on record, aviation industry faces redesign of newer and very important two products. FAA ordered a review of 787 design and EADS Airbus activates “Plan B” for the A350 XWB (battery option). The trigger for the 787 grounding and A350 design change were uncertainties presented the high performance Lithium batteries. The promising technology is under review and delays are expected on it´s broader use in airliners. Currently it has limited use e.g. for emergency lighting in A380. Boeing 787 was the first airliner using it as the only option as MAIN and APU battery. 787 FAA design review covers critical systems, including the design, manufacture and assembly.

Federal Aviation Administration 14 CFR Part 25 [Docket No. NM375 Special Conditions No. 25-359-SC] Special Conditions: Boeing Model 787-8 Airplane; Lithium Ion Battery Installation ACTION: Final special conditions.

Last edited by RR_NDB; 19th Feb 2013 at 01:06. Reason: Add link
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Old 16th Feb 2013, 16:13
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Some preliminary information

Hi,

Electrical “genius” at EADS Innovation Works is applied to a pioneering testbed aircraft




Boeing warns Dreamliner customers to expect delay in delivery of troubled jets


Lithium Fires Generate Myths and Misinformation



Batteries blamed in Boeing 787 grounding are widely used
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Old 17th Feb 2013, 21:59
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Short-term fix?

Hi,

Boeing readies short-term battery fix, facing uncertainty

Short term fix?

The issue is complex?

1. Corporate insanity?
2. Mountain of internal processes making the path forward glacial-speed?
3. Intense FAA review of certification found other serious non-battery concerns?
4. Battery charge/discharge electronics and software dispersed and tightly woven into the overall aircraft systems, making any change a vast undertaking?
5. Legal battles with suppliers?
6. ...?
From poorjohn at faa-grounds-787s
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Old 17th Feb 2013, 22:45
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Hi Mac.....

Isn't it illegal, (again), to carry the Heavy Lithium Ion Batteries in the hold?

Isn't the Aft E/E Bay in the hold? Isn't the "short term fix" actually carrying the Battery aboard?

I don't think the FAA will allow a fire on board, this time. Titanium or no, the word fire has a certain, cachet.....

If the cause of the original smoke/fire is not known, categorically, how can this short term fix be a......'fix'?

Is anybody talking to, or interviewing, the agency that has final say on what happens? Anticipating a plethora of arms in casts? Sorry, I injured my hand, I cannot sign anything......

Fundamentally, the Regulations speak. They were allowed to be "interpreted", and that's what created the current grounding.

They are not going to get more lenient, no matter who whistles and sings.

The more complex the "short term fix" the more attention drawn to why the design was so weak in the first place. And unless there is substantial work done on the cells, the interim launch solution is about keeping flames in a box.

Brilliant

Great thread, RR
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Old 18th Feb 2013, 03:23
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The forward and aft electronics bays are separate from the forward and aft cargo holds.

IMO, a more robust containment will be the short-term "fix" to lift the grounding order. Per an article in The Seattle Times, Boeing has 90 engineers in Japan at Yuasa assisting in "a complete redesign of the battery".

More stable cathode chemistries have either been developed or have matured since the original Lithium Cobalt Oxide chemistry was chosen. Switching to such a chemistry should both reduce the chance of thermal runaway (due to the higher temperatures needed to be reached) and if they do, they release significantly less heat.
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Old 18th Feb 2013, 14:02
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Hi Kiskaloo

The Fore/Aft Bays are indeed enclosed, separate from the Hold. My point was to bring up the irony of prohibition as Cargo, vice approved use as equipment.

But the problem remains regulatory. I stopped bangng on containment v/v regs. last week.

From the public information, admittedly a little "Lite", a more robust container does nothing to address the failures that caused the grounding.

As a regulator, the position should be: "Your address of the container makes an emphasis on the lack of performance of the system's existence...."

It is a safety system, a NOGO item, these Batteries. The stated purpose of this equipment is not "Must not catch fire", It is instead, "Must supply dependable power in Emergency". The need for any container at all flirts with making the design unsatisfactory as an autonomous system.....from a design perspective.

'Rehabilitation' is a noble cause. But not satisfactory given the performance record of the BATTERY; the container is not the problem.

A Lithium Battery of the mass used in the aircraft system cannot be loaded into a cargo hold. But it is acceptable if it is in a robust box in an inaccessible area of the a/c in flight?

Life imitates Fiction... Dr. Crichton might have come up with this plot.
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Old 18th Feb 2013, 16:22
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Leadership

Hi,

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Old 18th Feb 2013, 23:20
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Enclosing [robustly] something that may explode....won't that just make it worse
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Old 18th Feb 2013, 23:33
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Containment with (battery) redesign could be the "exit"

Hi,

Kiskaloo:

IMO, a more robust containment will be the short-term "fix" to lift the grounding order. Per an article in The Seattle Times, Boeing has 90 engineers in Japan at Yuasa assisting in "a complete redesign of the battery".
glad rag:

....won't that just make it worse
I think there is a fighting between engineers and high rocks.



Containment with (battery) redesign could be the "exit"
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Old 19th Feb 2013, 16:44
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glad_rag:
Enclosing [robustly] something that may explode....won't that just make it worse?
In the case of a sealed container, you would be correct. However, the current 787 container can vent (and did so in the case of JA804A) and the new container would include active venting to the outside of the plane. This is something Airbus has for the Li-Ion batteries on the A350XWB (and yes, I know Airbus will be moving to NiCad for certification and on production frames, but MSN003 and her sisters will start their flight tests with Li-Ion).

Interestingly, the 777 NiCad battery is in a sealed container. I guess they never expect anything to go wrong with it.
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Old 19th Feb 2013, 22:24
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Kiskaloo

The 777 battery isn't exactly sealed- it's got a cooling fan attached.
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Old 19th Feb 2013, 22:55
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Question 787 batt. redesign, K.I.S.S. version 1.0

Hi,

Why not:

2 similar batteries in parallel (same cells better separation, larger case)

Both PCB´s in separate chamber

Same (revised) BMS

Same charger (One for both batteries, "switched")

Improved sensing to shut off (battery) when one cell "starts" to fail

1 BDM per battery (MAIN)

Sturdier and vented (to outside) case.

Located nearby current positions (cable lenght optimization)

Total 4 batteries (2 MAIN, 2 APU)

Result: Better dependability, fault tolerant, graceful degradation, less fire risk, planes flying sooner (probable) and safer also because (batteries) could be derated.

Weight penalty: Aprox. "1 pax"

Please, BOMBARD it!

Last edited by Jetdriver; 19th Feb 2013 at 23:42.
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Old 20th Feb 2013, 05:21
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"Interestingly, the 777 NiCad battery is in a sealed container. I guess they never expect anything to go wrong with it."
For many moons, the L1011 TriStar has had proven track record with its 53kg NiCads in the pressurized mid electronics bay.
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Old 20th Feb 2013, 11:51
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4 batteries instead of 2 batteries
Please, BOMBARD it!
If the "runaway risk" isn´t eliminated, then there will be the double amount of nonnormal events.
Bad for statistics.
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Old 20th Feb 2013, 12:27
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In the case of a sealed container, you would be correct. However, the current 787 container can vent (and did so in the case of JA804A) and the new container would include active venting to the outside of the plane.
If the next event happens as JAL BOSTON did, there would be a grave danger of being drenched in flaming electrolyte, bits of battery, and extremely hot vapor?

Would not want to be a rampie, or a crew doing walkaround.
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Old 20th Feb 2013, 12:34
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20 February 2013 13:17:51Boeing Co Said to have found a fix for 787 Dreamliner battery problem - financial press (update)- Fix involves increasing the amount of space between battery cells to prevent overheating. ***Note that on Feb 17th, there were reports that a short-term 787 fix could come this week. The short term solution mentioned comprised a heavy-duty titanium or steel containment box around the battery cells, high-pressure evacuation tubes that, in the event of a battery fire, would vent any gases directly to the outside of the jet. - Source TradeTheNews.com
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Old 20th Feb 2013, 12:49
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787 batt. redesign, K.I.S.S. version 1.1

Hi,

RetiredF4:

If the "runaway risk" isn´t eliminated...
The idea is based on:

Cell failure MUST not generate battery dangerous heat: Cell separation (physically) could brings this "feature" (Larger case due this) and "Fault tolerance"

Cell failure MUST not degrade abruptly DC battery supply: Two batteries brings "fault tolerance"

Battery management system revision: this could improve cells / battery reliability through derating, better monitoring (per cell temperature, etc.) Statistics vs previous version tend to improve.

Sturdier, vented and AIR CIRCULATION case brings benefits on mitigation and reliability.

then there will be the double amount of non normal events.
Suppose the worst case: Cell´s still fail much more than expected. The likelihood of excessive battery heat leading to thermal runaway is lower than presently. (due better packaging: cell separation, circulating air and venting to outside of a/c.)

Bad for statistics.
Why:

Statistically (at a/c system level) this config. could even improve the a/c. The chance of non availability of battery supply for Bus (MAIN) or APU start will be lower.

The built in benefit is: Certification bureaucracy could led to faster 787 return to commercial operation.


PS


119.4:


Thanks news. Will look for details
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Old 20th Feb 2013, 15:04
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MAIN battery circuitry

Hi,

Finally an schematic diagram:

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Old 20th Feb 2013, 15:20
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Hi RR some questions....

Sturdier, vented and AIR CIRCULATION case brings benefits on mitigation and reliability.
With a "vented" enclosure at 41000 feet and 6000 pressure altitude inside, is there a problem? Wouldn't the drop in pressure in the box eject all the contents of the battery enclosure instantly? Explosive decompression?

Still havng a problem getting my head around FIRE/MITIGATION...

The combusted products, exiting the "vent" pipe, will not ignite the Hull?

God borbid the enclosure leaks burning electrolyte on to the fuselage structure, (epoxy resin), how is that potential "mitigated"?

I do not see how any fire can be allowed aboard any commercial aircraft?

What did I miss in the NTSB chief's statement re fire?

The logical solution for Boeing would be to install ceramic plates between each cell and add a vent to the battery box, Kiyoshi Kanamura, a professor at Tokyo Metropolitan University who has conducted research with several Japanese battery makers, told Reuters on Tuesday.
I'll have to check the ceramic reference for timing, I believe it was here on PPRuNe early on...

"Venting"? The box cannot be vented during operations, it would expose the cells to damaging pressure cycle flexing.

If it "Vented" only after fire, or whatever was alerted in the cockpit, the pressure differential would expel all contents out the overboard dump instantly.

I am sure BOEING have thought of that.

As to "Close" to a "solution".... Closer than at Certification?

Close counts in Horseshoes....

Last edited by Lyman; 20th Feb 2013 at 15:37.
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Old 20th Feb 2013, 15:43
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Cell detail

Hi,

No words on short of cell 3 tip region to ground?

Flashers anomaly (seems) commented

Observe the valve position is compatible with the "short to ground model" posted earlier:

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