Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Tech/Ops Discussion Of The 787 Grounding  
User currently offlineCM From , joined Dec 1969, posts, RR:
Posted (1 year 2 months 3 weeks 5 days 9 hours ago) and read 23897 times:

I'm starting a new conversation here.

In short:

>>The 787 uses Lithium-ion technology for its main and APU batteries. It is the first large commercial aircraft to use this battery technology in a large battery application.

>>Over a span of less than 2 weeks, 2 batteries in two separate 787s experienced thermal runaway events, causing a great deal of heat, smoke and, in the case of a JAL airplane on the ground in BOS, fire in the equipment bay.

>>After the first event, the NTSB opened an investigation and the FAA announced a full review of the 787 design and certification.

>>After the second event, ANA and JAL voluntarily grounded their 787 fleets, with the FAA issuing an AD to ground the US fleet the following day. All other regulators and airlines followed suit, with all 787s now grounded worldwide.

>>The FAA statement on the matter was, in part:

Quote:
"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.

The FAA will work with the manufacturer and carriers to develop a corrective action plan to allow the U.S. 787 fleet to resume operations as quickly and safely as possible.

The in-flight Japanese battery incident followed an earlier 787 battery incident that occurred on the ground in Boston on January 7, 2013. The AD is prompted by this second incident involving a lithium ion battery. The battery failures resulted in release of flammable electrolytes, heat damage, and smoke on two Model 787 airplanes. The root cause of these failures is currently under investigation. These conditions, if not corrected, could result in damage to critical systems and structures, and the potential for fire in the electrical compartment.

Last Friday, the FAA announced a comprehensive review of the 787’s critical systems with the possibility of further action pending new data and information. In addition to the continuing review of the aircraft’s design, manufacture and assembly, the agency also will validate that 787 batteries and the battery system on the aircraft are in compliance with the special condition the agency issued as part of the aircraft’s certification."

>>There is a great deal of speculation about what the root cause of these events was and ways Boeing might address them in order to return the aircraft to service.

This thread is for the purpose of discussing the events, the FAA action, the technologies involved, and Boeing's effort to get the aircraft back into service. This thread is not for conspiracy theories, speculation about corruption in the certification process, or other issue not directly related to the events and the technologies involved. If you want to discuss those topics, please join the threads in Civ Av, where your comments will be quite welcomed.

Thanks!

CM

[Edited 2013-01-24 04:48:33 by Wilco737]

238 replies: All unread, showing first 25:
 
User currently offlineStitch From United States of America, joined Jul 2005, 29686 posts, RR: 84
Reply 1, posted (1 year 2 months 3 weeks 5 days 8 hours ago) and read 23890 times:
Support Airliners.net - become a First Class Member!

Before those two incidents, the 787-8 had over 100,000 hours of in-service operation without either the Ship's or the APU battery suffering a fire or leaking electrolyte.

The NH airframe - JA804A - was delivered a year prior to the incident. It was the 9th 787 airframe to begin construction.

The JL airframe - JA829J - was delivered less than three weeks prior to the incident. It was the 84th 787 airframe to begin construction and the most recent 787 airframe delivered to a customer.

The Ship's Battery on JA804A (the NH airframe) had been replaced in October 2011. The stated reason for this was because the original battery could not start the engines. However, the Ship's Battery is not used to start the engines, so it may be a case of mistranslation (the original report was from Japanese media) or a miscommunication (the Ship's Battery can assist the APU battery in starting the APU).

There have been reports in the Japanese media that the two batteries may be from the same production batch.

The NTSB has been quoted as saying that the battery on JA829J was not subjected to charging voltages higher than it was designed to handle.

Japanese government officials have been quoted as saying that the battery on JA804A was subjected to charging voltages higher than it was designed to handle.

I have received an unconfirmed, third-hand report that a software update to the charging system was applied to a number of 787-8s recently, The details of this update are not known, though it has been said they changed the charging controls and algorithms. I also do not know which 787-8 airframes received this update (again, assuming such an update did occur).

[Edited 2013-01-22 11:00:29]

User currently offlinekanban From United States of America, joined Jan 2008, 3212 posts, RR: 26
Reply 2, posted (1 year 2 months 3 weeks 5 days 7 hours ago) and read 23830 times:
Support Airliners.net - become a First Class Member!

CM, while I applaud the idea of a fact and data driven thread, the trollers and conspiracy theorists will find this sooner or later.

I'm afraid that it will still cause you, Tom, Stitch and others to be monitoring both forums and answering questions twice.

case inn point, I just finished a post in the other forum asking about the flammability or the electrolyte.. I could cut an paste it here however I'm leaving it as just one post.


User currently offlinenomadd22 From United States of America, joined Feb 2008, 1764 posts, RR: 0
Reply 3, posted (1 year 2 months 3 weeks 5 days 7 hours ago) and read 23805 times:

I hear a lot about excessive charging voltage (or lack of) but that's not really the factor in the failures I'm familiar with. You always have to use a high voltage for the final portion of the charge to get that last 10% or so. Cheap batteries might just have a thermistor to limit current when the battery get to a certain temperature, but there's no chance they used that on the 787. That algorithm has to be one that analyzes the voltage to current over time curve to sense end of charge and cut the voltage back down to maintenance, or whatever they call it. I'd hope that it also predicts battery problems by sensing abnormal charging curves.
This would be a lot more fun with some details of the charging/monitoring system. Damn their proprietary eyes anyhow.
I'm guessing a two part fix. Inspection, some replacement and quality control measures to get them airborne. Maybe a 90% charge limit or additional monitoring that wouldn't change anything to the extent of needing new, drawn out certification.
Long term, something that will take a while. A major change in the charging and monitoring in order to predict trouble and disconnect cells before grief ensues. Along with procedure to make sure sub par batteries don't find their way to a plane. Much depending on if the problem was design, production or something else.

I'm not sure if I'd put my money on Japanese government official comments. It's just too easy to prevent or detect higher than designed for voltage.

[Edited 2013-01-22 12:12:11]


Andy Goetsch
User currently offlinenomadd22 From United States of America, joined Feb 2008, 1764 posts, RR: 0
Reply 4, posted (1 year 2 months 3 weeks 5 days 6 hours ago) and read 23791 times:

By the way. I probably missed it in the last 800 posts, but are we talking about cobalt oxide cathodes?


Andy Goetsch
User currently offlineCubsrule From United States of America, joined May 2004, 22304 posts, RR: 20
Reply 5, posted (1 year 2 months 3 weeks 5 days 6 hours ago) and read 23798 times:

One question I have is what assumptions Boeing and Airbus made when they incorporated lithium ion technology in to the 787 and 350. I understand the benefits, but what did Boeing and Airbus decide about thermal runaway and safety that is different today from when the 380 was developed with only minimal use of lithium ion batteries?


I can't decide whether I miss the tulip or the bowling shoe more
User currently onlineKELPkid From United States of America, joined Nov 2005, 6264 posts, RR: 3
Reply 6, posted (1 year 2 months 3 weeks 5 days 6 hours ago) and read 23768 times:

I'm gonna repeat the post I just made in the civ/av thread after taking a look at the picture of the battery box after the flight (before it was cracked open):

On the surface, doesn't look too bad...I remember a battery box (containing a lead acid battery) looking like this after a coworker hooked up 28 volts DC to a poor Cessna 150 with a 12 volt electrical system and a dead battery... Fortunately, no one ever turned the master switch on in the 150 before the coworker realized the mistake. The mechanic was able to replace the fried battery and clean up the acid that boiled out of the battery box the same day. And yes, battery acid dripped down out the bottom of the cowling



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 7, posted (1 year 2 months 3 weeks 5 days 6 hours ago) and read 23759 times:

Quoting Stitch (Reply 1):
Before those two incidents, the 787-8 had over 100,000 hours of in-service operation without either the Ship's or the APU battery suffering a fire or leaking electrolyte.

Yes. Someone else suggested the total flying time between airline operations and flight test should be a bit over 100,000 hours. I could go verify that number as I have access to operational hours by tail number, but then I couldn't post on here about it - so let's call it 100,000 hours before the incidents. Sometimes it's better to not know things precisely!  

Mike Sinnett (787 Chief Project Engineer) also stated the batteries have 1.3 million total operating hours, between labs, flight test airplanes and the in-service fleet.

Quoting kanban (Reply 2):
CM, while I applaud the idea of a fact and data driven thread, the trollers and conspiracy theorists will find this sooner or later.

It is why I didn't post this link in the other thread. Perhaps this will give us a little time to discuss things intelligently.

Quoting nomadd22 (Reply 4):
By the way. I probably missed it in the last 800 posts, but are we talking about cobalt oxide cathodes?

As far as I am aware, the batteries are Lithium Cobalt Oxide. At one point the batteries were Lithium Manganese, but my recollection is the chemistry was changed for some reason. It may have been to achieve longer on-wing life for the batteries, but I may not be remembering that exactly right.

Quoting kanban (Reply 109):
we have discussed that the electrolyte is flammable.. but at what temperature? does the boiled extruded goo have the same or a significantly high ignition temperature? Does that "boiling" reduce the toxicity or encapsulate it so corrosion of surrounding metal is not at risk? My concern with building a double hull type containment is it would not allow the goo to cool which could exacerbate problems. If it runs out the port and hardens or vents from the a/c, it is less likely to ignite than if pooled around a thermal run away.

I don't know the answers to this, but I bet there is a battery expert or a fire chief out there who can help us with this. Let's hope one of those with these qualifications from the other thread drifts over.

Quoting rheinwaldner (Reply 117):
The A350 needs equally good battery solutions as the 787 obvioulsly. Airbus even mentions an additional delay, if corrections are needed. The difference is, that the total installed battery capacity is much smaller, and yet the number of cells is higher. So a single cell is less vulnerable and has less capacity to do harm.

This comment caught my attention. I have a copy of an A350 systems description which includes this explanation of the A350 batteries:

Quote:
Batteries DC generation:
Four identical Lithium-Ion batteries are connected to the 28 V DC network in order to:
- Ensure the No Break Power Transfer function
- Provide standby DC power
- Provide DC power on ground if AC power is not available .
Two out of the four batteries can provide temporary supply in an emergency configuration.

If only 2 of the 4 A350 batteries provide standby power, it is clear there was not an attempt by Airbus to reduce the size of the batteries by splitting them into 4 batteries instead of the traditional 2. Also, the standby power loads between the A350 and 787 will not be dramatically different. For example, the 787 and 777 have nearly identical standby power loads on the battery with the one difference being the need for additional capacity for electric braking on the 787 when the RAT drops below a certain speed. Because of this, I am of the opinion the A350 has 4 rather normal sized Lithium-ion batteries, not 4 half-sized batteries, as is being suggested. It adds relevance to this comment from the other thread:

Quoting Kaiarahi (Reply 111):
The Airbus Director of Programs is on record as saying that an adverse outcome of the Boeing Li-Ion issue would have a significant impact on the A350.


User currently offline817Dreamliiner From Montserrat, joined Jul 2008, 2070 posts, RR: 1
Reply 8, posted (1 year 2 months 3 weeks 5 days 5 hours ago) and read 23679 times:

Ive havent been following the previous threads on the topic due to the Boeing haters and trolls, but im glad you've started this thread here CM. I don't want to start speculating but here's my take on the battery accidents:

Quoting Stitch (Reply 1):

Before those two incidents, the 787-8 had over 100,000 hours of in-service operation without either the Ship's or the APU battery suffering a fire or leaking electrolyte.

And you can also include the many hours of flight testing that was done with the 6 test aircraft. The only exception would be the fire that occurred on ZA002, though im sure that is not related to the current battery issue.

Quoting Stitch (Reply 1):
There have been reports in the Japanese media that the two batteries may be from the same production batch.

This is Exactly what I thought, when details of the second Incident were released. However, im sure this hasn't been fully proven as yet. As noted above the 787 has been in service for over a year, plus a year and a half of flight testing. If it really was a li-Ion battery design problem it should have came up in flight testing, which lead me to believe that the two batteries came from the same batch.

Quoting Stitch (Reply 1):

The Ship's Battery on JA804A (the NH airframe) had been replaced in October 2011. The stated reason for this was because the original battery could not start the engines. However, the Ship's Battery is not used to start the engines, so it may be a case of mistranslation (the original report was from Japanese media) or a miscommunication (the Ship's Battery can assist the APU battery in starting the APU).

Is that supposed to be October 2011 or 2012? Can you post the link to this?

Quoting Stitch (Reply 1):
I have received an unconfirmed, third-hand report that a software update to the charging system was applied to a number of 787-8s recently, The details of this update are not known, though it has been said they changed the charging controls and algorithms. I also do not know which 787-8 airframes received this update (again, assuming such an update did occur).

While unconfirmed, it would be interesting if this did occur, again don't really want to speculate, but a software update causing the problem actually sounds plausible... What would be the process of testing a software update before its released to aircraft?

Also, I read a rumour on another site that the JL 787 might be written off, but as I said that's just a rumour. I don't think the damage was that bad to write it off...



Reality be Rent. Synapse, break! Vanishment, This World!
User currently offlineStitch From United States of America, joined Jul 2005, 29686 posts, RR: 84
Reply 9, posted (1 year 2 months 3 weeks 5 days 5 hours ago) and read 23660 times:
Support Airliners.net - become a First Class Member!

Quoting 817Dreamliiner (Reply 8):
Is that supposed to be October 2011 or 2012?

2012.


User currently offlinePITingres From United States of America, joined Dec 2007, 1087 posts, RR: 13
Reply 10, posted (1 year 2 months 3 weeks 5 days 2 hours ago) and read 23464 times:

Curiosity question: How much room is there around the two battery enclosures? If part of the solution is to wrap the box in a sort of "drip tray", or rework the enclosure to give some level of individual cell containment, it's obviously going to make the total package larger. Is there any room to work with or is the battery going to have to maintain its current form factor?

Quoting kanban (Reply 2):
...the trollers and conspiracy theorists will find this sooner or later.

Well, I for one will have no compunction about using the delete post button. Let's hope the mods can keep this thread clean at least for a while.



Fly, you fools! Fly!
User currently offlineStitch From United States of America, joined Jul 2005, 29686 posts, RR: 84
Reply 11, posted (1 year 2 months 3 weeks 5 days 2 hours ago) and read 23453 times:
Support Airliners.net - become a First Class Member!

There is a drawing of the forward and aft EE bays at the start of this PPrune thread, but I do not know how accurate they are. If the drawing is accurate to scale, then it looks like there may be room around it.

ADent in Reply 105 of the FAA Grounds 787 Part 4 (by iowaman Jan 21 2013 in Civil Aviation)#1 thread also showed a picture of the Ship's Battery on JA804A in-situ and it does look like there is a bit of extra room around it.


User currently offlineBEG2IAH From United States of America, joined Apr 2004, 892 posts, RR: 15
Reply 12, posted (1 year 2 months 3 weeks 5 days 1 hour ago) and read 23422 times:
Support Airliners.net - become a First Class Member!

Quoting kanban (Reply 2):
I just finished a post in the other forum asking about the flammability or the electrolyte..

I've been searching for the answer and what I found so far says the electrolyte is flammable. Actually, when you read more it says the vapors are flammable and they would need a source of ignition to burn. It does not self ignite! There is a lot of research into new electrolytes that add flame retardants, such as this one:
http://www.targray.com/li-ion-battery/electrolyte.php

Here are the sources and excerpts:

1) http://www.sbir.gov/sbirsearch/detail/15939
Commercially available lithium-ion cells use an electrolyte containing a mixture of organic carbonate solvents combined with lithium hexafluorophosphate (LiPF6). These electrolytes have significant disadvantages limiting the performance and safety of lithium-ion batteries. First, the solvents are volatile and flammable, leading to safety issues during production, storage and use of batteries and their behavior under abuse conditions. Second, LiPF6 is not hydrolytically or thermally stable in organic carbonates, leading to degradation of electrolyte, rise in electrode/electrolyte interface impedance, dissolution of active cathode materials and limited battery life. Thirdly, present electrolyte solutions appear to be reactive towards cathode materials at high voltages, which contribute to battery performance deterioration. It also prevents further development of future higher energy cells with 5V cathode materials. Finally, present electrolyte formulations are always a compromise; no one mixture of the solvents has been shown to work well at both low and high temperatures.

2) http://prod.sandia.gov/techlib/access-control.cgi/2012/129186.pdf
For lithium ion rechargeable batteries, these electrolytes are almost universally based on lithium hexafluorophosphate (LiPF6) salts with combinations of linear and cyclic alkyl carbonates. These electrolytes enable the use of lithium as the negative electrode active component and results in the high power and energy densities characteristic of the Li-ion chemistries. However, these organic electrolyte solvents have high volatility and flammability that pose a serious safety issue for their use in the consumer and transportation markets. For example, gas generation in Li-ion cells under abuse conditions has an effect on safety because gas production, if generated at sufficient pressure will vent flammable solvent vapor into the surrounding environment. The resulting fuel-air mixture can be quite explosive and only requires an ignition source to ignite the vapors. LiPF6 is known to react with carbonate solvents at elevated temperature and in the presence of moisture to generate large gas volumes of decomposition products [2-4].

3) http://www.electrochem.org/dl/interface/sum/sum12/sum12_p045_049.pdf

4) http://144.206.159.178/ft/641/92454/1607448.pdf
The electrolyte for these batteries typically consists of ethylene carbonate with a high dielectric constant and an alkyl carbonate as a low viscosity solvent containing the LiPF6 salt. These solvents are flammable. When the internal pressure of the battery increases and the battery is mechanically destroyed, the electrolyte could be led to the dangerous situations such as fire and explosion. These accidents were thought to be related to the flammability of common carbonate-based electrolytes. Therefore, it has been becoming important to find effective method to suppress the flammability of lithium-ion batteries.

5) Wikipedia (this talks about the properties of LiPF6 salt, which by itself is not flammable)
http://en.wikipedia.org/wiki/Lithium_hexafluorophosphate
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source. At the flash point, the vapor may cease to burn when the source of ignition is removed. The flash point is not to be confused with the autoignition temperature, which does not require an ignition source, or the fire point, the temperature at which the vapor continues to burn after being ignited. Neither the flash point nor the fire point is dependent on the temperature of the ignition source, which is much higher.

I'm fundamentally challenged when it comes to chemistry (just a dumb economist here) so I hope this helps a bit. Please don't ask me for any follow ups.  

[Edited 2013-01-22 17:50:20]


FAA killed the purpose of my old signature: Use of approved electronic devices is now permitted.
User currently offlinekanban From United States of America, joined Jan 2008, 3212 posts, RR: 26
Reply 13, posted (1 year 2 months 3 weeks 4 days 22 hours ago) and read 23305 times:
Support Airliners.net - become a First Class Member!

Quoting BEG2IAH (Reply 17):
I'm fundamentally challenged when it comes to chemistry

I am also.. failed chemistry so bad had to switch to an art major..
Thanks , some of it made sense.. hopefully tdscanuck or CM will translate to layman's terms.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 14, posted (1 year 2 months 3 weeks 4 days 22 hours ago) and read 23302 times:

Quoting kanban (Reply 20):
I am also.. failed chemistry so bad had to switch to an art major..
Thanks , some of it made sense.. hopefully tdscanuck or CM will translate to layman's terms.

Hated chemistry so much I took Chemistry AP in high school just so I could avoid taking it as an undergraduate. Never took a chemistry course again, although it kept popping up annoyingly in other contexts.

Tom.


User currently offlineStitch From United States of America, joined Jul 2005, 29686 posts, RR: 84
Reply 15, posted (1 year 2 months 3 weeks 4 days 22 hours ago) and read 23278 times:
Support Airliners.net - become a First Class Member!

Quoting BEG2IAH (Reply 17):
I've been searching for the answer and what I found so far says the electrolyte is flammable. Actually, when you read more it says the vapors are flammable and they would need a source of ignition to burn. It does not self ignite!

So it is possible that with the outflow valve actively clearing the air in the EE bay, then even an electrolyte stream might not ignite due to the flammable vapors being expelled from the bay?


User currently offlineCALTECH From Poland, joined May 2007, 2004 posts, RR: 27
Reply 16, posted (1 year 2 months 3 weeks 4 days 21 hours ago) and read 23271 times:

Quoting CM (Reply 7):
As far as I am aware, the batteries are Lithium Cobalt Oxide. At one point the batteries were Lithium Manganese, but my recollection is the chemistry was changed for some reason. It may have been to achieve longer on-wing life for the batteries, but I may not be remembering that exactly right.

As relayed to us, the composition of the electrolyte was changed as the batteries were only lasting 6 months. With the new composition, battery service life has gone up to approx 4 years. Oxides had been added to the composition is what has been said.

These 787 batteries, they are high energy and high heat. There were concerns about the temperature generated during periodic main/APU battery capacity checks to be performed on the aircraft, as proposed. Believe our airline is so concerned with the heat generated and relying on a test box to prevent a thermal runaway durng the capacity check, that the batteries will be removed from the aircraft for these capacity checks.

Also, unlike the Ni-Cad batteries, if a bad cell is encountered on these 787 batteries, it supposedly needs all the cells replaced for cell voltage balancing.

787 has a voltage below which it cannot be recharged.The battery has an auto-shutdown program to prevents cell damage from further voltage loss.

In tests, the 787 batteries have been dropped from aircraft E&E hatch height, and then steel rods were driven through the battery, all with no explosive effect. It hasbeen said that the new Li-ion chemistry in this battery – the electrolyte is a paste composed mainly of Li ion solution, cobalt, and a proprietary powder – is a much more stable chemistry than earlier and other Li-ion chemistries.

It has been said that there is no going back to Ni-Cad. This is a interesting aircraft. The leap in new technologies will take some getting used to. Can not wait to fly on one .



UNITED We Stand
User currently offlineBEG2IAH From United States of America, joined Apr 2004, 892 posts, RR: 15
Reply 17, posted (1 year 2 months 3 weeks 4 days 21 hours ago) and read 23248 times:
Support Airliners.net - become a First Class Member!

Quoting CALTECH (Reply 23):
In tests, the 787 batteries have been dropped from aircraft E&E hatch height, and then steel rods were driven through the battery, all with no explosive effect. It hasbeen said that the new Li-ion chemistry in this battery – the electrolyte is a paste composed mainly of Li ion solution, cobalt, and a proprietary powder – is a much more stable chemistry than earlier and other Li-ion chemistries.

CALTECH, would that mean "flame retardant" might be part of that new proprietary chemistry?



FAA killed the purpose of my old signature: Use of approved electronic devices is now permitted.
User currently offlineCM From , joined Dec 1969, posts, RR:
Reply 18, posted (1 year 2 months 3 weeks 4 days 20 hours ago) and read 23355 times:

Quoting 817Dreamliiner (Reply 8):
Also, I read a rumour on another site that the JL 787 might be written off, but as I said that's just a rumour. I don't think the damage was that bad to write it off...

I don't have any direct knowledge of either battery incident, but the photos I've seen of the JL airplane sure wouldn't point in this direction. Let's imagine an extreme scenario: if the entire rack which housed the battery needed to be replaced (P150 panel, WIPS controller, APU battery charger, etc), plus the airplane required a major structural repair in the bilge area below the battery, I am still confident the cost of this repair would fall far short of what would make the insurer consider writing the frame off as a hull loss. I would guess the airplane to be valued by an appraiser at between $125 and $150 million. The cost of the repair would need to approach 50% of this before it would be written off.



Quoting kanban (Reply 20):
hopefully tdscanuck or CM will translate to layman's terms.

Not to create a theme, but Would you believe you can get both mechanical and aero degrees with nothing more than grade 10 chemistry? I hated it, did poorly in it, and retained none of it. I will truly be of no use to you on topics of chemistry.



Quoting Stitch (Reply 22):
So it is possible that with the outflow valve actively clearing the air in the EE bay, then even an electrolyte stream might not ignite due to the flammable vapors being expelled from the bay?

I doubt this very much. The normal ventilation of the equipment bays is designed with just enough pressure differential to keep steady airflow through the bay for cooling reasons. There are fans in the system, but the negative pressure at the outflow valve will keep things moving even without them. If smoke is detected, there is a second "outflow valve" (called the override valve) which automatically opens and increases the venting of the bay. Even with this second valve open, the intent is to have just enough negative pressure relative to the rest of the airplane that it would not be possible for smoke to migrate from the equipment bay into the main deck. It is by no means a massive vacuum evacuating the bay. A man wearing a toupee would certainly be safe in there, even with the override valve open  



Quoting CALTECH (Reply 23):
It has been said that there is no going back to Ni-Cad.

I know many in the other threads were asking why Boeing is not just making a Ni-Cd battery for the 787 and being done with this issue altogether. There are distinct differences in the power provided by each battery, which is why I believe your statement is mostly correct; a swap of battery technologies might be possible, but it would not be straightforward. A Ni-Cd cell has a marked voltage decay from peak charge to its depleted state. A Li-ion cell holds a much more constant voltage as it discharges. Among the many desirable aspects of Li-ion batteries, I believe the power quality they produce (and systems which were designed to take advantage of it) may make it very hard for Boeing to change battery types at this point.


User currently offlineCALTECH From Poland, joined May 2007, 2004 posts, RR: 27
Reply 19, posted (1 year 2 months 3 weeks 4 days 19 hours ago) and read 23286 times:

Quoting BEG2IAH (Reply 24):
CALTECH, would that mean "flame retardant" might be part of that new proprietary chemistry?

As in adding 'flame retardant' ? No. It is just a more stable chemistry. And the new composition of the electrolyte was done quite some time ago, they may play with it some more.

Quoting CM (Reply 25):
I know many in the other threads were asking why Boeing is not just making a Ni-Cd battery for the 787 and being done with this issue altogether. There are distinct differences in the power provided by each battery, which is why I believe your statement is mostly correct; a swap of battery technologies might be possible, but it would not be straightforward. A Ni-Cd cell has a marked voltage decay from peak charge to its depleted state. A Li-ion cell holds a much more constant voltage as it discharges. Among the many desirable aspects of Li-ion batteries, I believe the power quality they produce (and systems which were designed to take advantage of it) may make it very hard for Boeing to change battery types at this point.

Spot on. It is and could be possible to go to a Ni-Cad battery, but very unlikely for all those reasons you posted, at least up to this pont in time.

[Edited 2013-01-22 23:42:52]

[Edited 2013-01-22 23:43:51]


UNITED We Stand
User currently offlinekanban From United States of America, joined Jan 2008, 3212 posts, RR: 26
Reply 20, posted (1 year 2 months 3 weeks 4 days 19 hours ago) and read 23318 times:
Support Airliners.net - become a First Class Member!

Quoting CM (Reply 25):
Not to create a theme,

dang.. what a crowd!!! well maybe there is a chemist out there.

RCAIR1 had some interesting observations and new understandings about these batteries and their properties on the AV thread..


User currently offlineKC135Hydraulics From United States of America, joined Nov 2012, 270 posts, RR: 0
Reply 21, posted (1 year 2 months 3 weeks 4 days 17 hours ago) and read 23283 times:

Hey guys,

Much prefer the discussion on this forum than on civil aviation! I also posted this picture there, but I thought it'd be interesting for conversation here. These are the batteries on the KC-135. They are lead-acid, 28v. These are kept in the latrine... as you can see, the toilet on the left and the urinal can to the right.




Battery charger controller is mounted just above the circuit breaker panel.


User currently offlinenomadd22 From United States of America, joined Feb 2008, 1764 posts, RR: 0
Reply 22, posted (1 year 2 months 3 weeks 4 days 15 hours ago) and read 23187 times:

Quoting CALTECH (Reply 23):
Also, unlike the Ni-Cad batteries, if a bad cell is encountered on these 787 batteries, it supposedly needs all the cells replaced for cell voltage balancing.

It's more important for the cells to be perfectly matched in a series to prevent overcharging one of them with Lithium.

Quoting CALTECH (Reply 23):
It hasbeen said that the new Li-ion chemistry in this battery – the electrolyte is a paste composed mainly of Li ion solution, cobalt, and a proprietary powder – is a much more stable chemistry than earlier and other Li-ion chemistries.

I don't have anything to back it up, but we'd always gathered that the cobalt chemistry was one of the less safe ones and was used for greater capacity and voltage. An iron oxide setup would have needed one more cell to get the same voltage. I gather you're referring to the proprietary solution, and not being cobalt based.



Andy Goetsch
User currently offlineAviaponcho From France, joined Aug 2011, 581 posts, RR: 8
Reply 23, posted (1 year 2 months 3 weeks 4 days 15 hours ago) and read 23194 times:

Hello guys

Did you see (here ?) this one

http://www.usatoday.com/story/travel.../01/23/japan-boeing-probe/1857647/

Quote:

Japan Transport Safety Board chairman Norihiro Goto told reporters the jet's data recorder showed the main battery, used to power many electrical systems on the jet, did not exceed its maximum voltage. That contradicts an earlier assertion by the agency as it investigates with the U.S. Federal Aviation Administration.

All 50 of the 787 Dreamliners that Boeing has delivered to airlines were grounded after the emergency landing by the ANA flight in western Japan on Jan. 16. Boeing has halted deliveries of new planes until it can address the electrical problems.

Goto said the maximum voltage recorded for the battery was 31 volts, which was below its 32 volt limit. But the data also showed a sudden, unexplained drop in the battery's voltage, he said.

Aircraft do not usually use the kind of lithium ion battery chosen for the 787, and investigators are still struggling to figure out what may have gone wrong.

"It's not that it is difficult, but that we are not so familiar with it," Goto said.

The Transport Safety Board said it also will study the aircraft's auxiliary battery and compare data from each.

So no overcharging at the battery level for the 2 failures..
and Japanese backpedalling by the way

[Edited 2013-01-23 03:49:12]

User currently offlinercair1 From United States of America, joined Oct 2009, 1292 posts, RR: 52
Reply 24, posted (1 year 2 months 3 weeks 4 days 13 hours ago) and read 23088 times:
AIRLINERS.NET CREW
CUSTOMER SERVICE & SUPPORT

I, too, have tried to escape the other thread here. Thanks to CM for starting it.

I posted the following in the other thread last night after spending a lot of time doing research into new areas.

To my chagrin - I found that some of the information I had posted on Li-Ion batteries applies only to Li primary (non-rechargeable) batteries.
My apologies to all for being incorrect!
------
So - I got really tired of reading patents today and so I started looking for concrete new data on Li-Ion battery fire danger and suppression techniques. I even spent a fair amount of time reading about "bricking" your Telsa.

I've discovered some errors in what has been posted here, including errors that I made.

To be clear - the information I provided was based on training I received in an alternative fuels class I took about 4 years ago - and it seems like the understanding is evolving.

First - the biggest source of misunderstanding is confusing Lithium and Li-Ion battery chemistry and the approaches to fighting a fire in both cases.

In Lithium battery fires - these are non-rechargable Li Batteries - known as primary batteries - there is significant metallic Lithium. This is a true metal class fire and requires class D extinguishing agents. Conventional extinguishers - ABC as well as Halon, and most especially water - do not work.
-> My training was focused on this - and either I missed the following, or it was not covered.

In Lithium-Ion rechargeable batteries - secondary batteries - there is little metallic Lithium. You can use water or class ABC extinguishing agents - though the efficacy of them is unproven. The primary fire hazard for a Li-Ion battery is 2 fold - heat due to thermal runaway and flammable electrolyte/vent gas. The big difference - which I have just learned - is that the electrolyte in a Li-Ion battery is more flammable that the electrolyte in other batteries (like NiCad or NiMH) because it is not water base. Those other electrolytes pose much higher corrosion and toxicity concerns, but lower fire concerns.

Tests seem to indicate that conventional techniques, if they could be applied, would be effective in extinguishing the flame - however, the danger posed by re-kindle is major.
For instance, Halon 1301 is shown to be effective extinguishing the flame (electrolyte/gas), but not cooling the battery. If you use Halon, you will likely face re-kindle. An effective suppression would need to persist - to remain on the fire long enough to extinguish re-kindles long enough for thermal runaway to terminate. Water is effective in cooling, except that the design of the battery makes it difficult/impossible to apply well enough to overcome the heating of a thermal runaway.

It is interesting to note the 2 methods discussed for aircrews to deal with runaway fires in consumer batteries (laptops) are to 1) douse them repeatedly with water or 2) put them in a containment bag. The containment bag is designed to contain the heat long enough for runaway to terminate and the fire to go out. No effort is made to contain vent gasses in these containment bags. The reports I read seemed to indicate the containment bag was a better approach - it was surer.

It is also unclear if "spreading" the electrolyte by washing it around with water is a concern.

So - the primary issue extinguishing a Li-Ion battery fire is that, while you can potentially extinguish the 'flame' you cannot effectively cool a battery in thermal runaway well enough to prevent re-kindle of either the electrolyte or gasses being expelled. A Halon extinguishing system in the EE bay would be ineffective - it may put out flames (if they are outside the containment), but would not cool the battery. Thermal runaway would continue and re-kindle would be likely.

BTW - the data I could find so far indicates that the flammability limit LFL to UFL for vented gasses is small. LFL is the concentration in air below which the gas is non-flammable (too lean) and UFL is the concentration above which it is not flammable (too rich). A narrow flammability range means that an effective control method is to either concentrate or disperse the gas. The latter is obviously the better choice. Therefore - effective and positive ventilation is important.

One of the better references I've been studying is research performed by the Fire Protection Research Foundation - funded by the NFPA (National Fire Protection Association) - an organization I work with a lot.

The report I reference is located at the link below and was dated July 2011. I might refer you to Chapter 6 (page 84) and beyond.

The obvious question one may ask is does this change my opinion on the situation the 787 and Boeing face. The answer I have is - I'm sure - not going to satisfy some. Simply stated - I don't know yet - I need more data.

It seems that containment and venting (if those are not contradictory terms) are still the best approach based on the data I have seen. Vent the gas to keep it below LFL. Contain the fire so it says in the 'box'.

I do have a concern about the leaked electrolyte. Based on the new knowledge I spent the afternoon gaining (not from a.net by the way), my level of concern is increased. If it is flammable - and it appears it may be (since we do not know the exact composition of the Yuasa batteries, I can't say for sure) it represents a hazard. Is it a hazard that can be managed by placing it in a location where, if ignited, it will consume itself and burn out without the fire extending - then - no. If it the fire could extend - then yes. I would caution you that even the NFPA report I'm citing states that Li and Li-Ion battery chemistry varies dramatically and they are careful not to point out that testing all the types of chemistry is beyond the scope of their research.

These are questions that need to be reviewed and answered. Of course - that is exactly what Boeing and the FAA is doing.
http://www.nfpa.org/assets/files/pdf...ch/rflithiumionbatterieshazard.pdf

My apologies for misinforming that re-chargeable Li-Ion secondary batteries require Class D

[Edited 2013-01-23 06:10:03]


rcair1
25 Stitch : That does appear to be the case with Lithium cobalt oxide (which is what the 787's batteries use). They are more susceptible to thermal runaway in ca
26 Post contains links rcair1 : The NFPA report I mentioned (re-linked here) discusses the energy content and flammability of a 16850 cell- this a typical cell used in consumer batt
27 moose135 : If it even got to that point, I suspect Boeing might eat some (or most) of the cost of repairs simply to avoid the PR issue of having a 787 written o
28 Kaiarahi : NTSB update from Jan 20 that I haven't seen referenced (although I could have missed it on the CivAv compost heap). Major points: JL battery being dis
29 Post contains links kanban : a revision from AV Herald http://avherald.com/h?article=45c377c5&opt=6144 "Attending emergency services found no trace of fire, however traces of
30 tdscanuck : I'm not sure...it looks like they took the battery and everything the battery interfaces with. That seems more like the shotgun approach (investigate
31 Kaiarahi : If I remember (not sure of the source of the info, though), the APU was running in BOS. Which means it was started relatively recently before the fir
32 TheSultanOfWing : Folks, I tried to have this question answered in the "other" dreaded thread as well, so here goes: Is Boeing physically checking each airframe deliver
33 Post contains links and images airmagnac : Hi CM (and everyone) I've been meaning to build on your thoughts in reply 38 from FAA Grounds 787 Part 4 (by iowaman Jan 21 2013 in Civil Aviation) f
34 CM : Thanks for this. I always do better when I can visualize things! Just a couple quick comments: First, I agree with your modification and distinguishi
35 Post contains images PITingres : I might be one of the (few?) non-chemistry-haters here, although I never studied it at an advanced level. (Did plenty of messing around in the basemen
36 rcair1 : I like your representation. I do have some comments. For instance, you show the "release of flammable electrolyte" and "battery fire inside container
37 tdscanuck : Do you think Poisson is the right distribution model to apply here? I know we don't know the underlying failure mechanism but I have a tough time thi
38 Post contains links faro : From the following thread in Tech/Ops: Battery Container Contributing To Li-Ion Failure? (by faro Jan 18 2013 in Tech Ops) I thought a couple of quest
39 Tristarsteve : I was reading a presentation on the B787 at work, and there was one slide about batteries. It showed that Yuasa also makes the batteries for the fligh
40 zeke : I think anyone that has flown electric models knows that if one tries hard enough, one can make any sort of battery technology from any manufacturer
41 CALTECH : Besides the Main and APU battery set, there are 3 sets of flight control emergency batteries. Haven't heard of any problems with these. In normal fli
42 rcair1 : I'm reposting portions of a previous post that was removed because it quoted a post that quoted a post that quoted a post that was removed because tha
43 Post contains images WingedMigrator : Ditto here... re-posting deleted stuff: If we assume the underlying failure rate is constant, i.e. we are not dealing with an infant mortality issue I
44 tdscanuck : I think so. The use of Li-ion in small backup emergency batteries is pretty well established (the A380's been doing it without issue for many years).
45 zeke : In brand A aircraft I am only used to seeing batteries receiving a short charge in flight and then disconnecting from the charge (to bring the batter
46 PITingres : I'll also repost my wild-eyed notion of using an aerogel within the containment case to enhance cell separation. The stuff is supposed to be an excell
47 Pihero : Anybody has gen on the NTSB press conference that was supposed to happen @ 0230pm est ? /[Edited 2013-01-24 11:06:38]
48 Stitch : Looks to still be planned to start in 10 minutes. There does not appear to be a public-facing option to follow in real-time - no webcast and CSPAN/CS
49 Post contains images Pihero : I know we can count on you for a report !
50 Post contains links BoeEngr : It's currently live on NBC: http://video.msnbc.msn.com/nbcnews.com/50575001/#50575001
51 Post contains links Stitch : Thanks. I came in at the tail-end of the Q&A session, but I heard the spokeswoman noting there was a thermal runaway and short-circuiting inside
52 BoeEngr : I didn't find it overly informative. She confirmed they have, to this date, ruled nothing out, and re-affirmed (multiple times) that they are investi
53 Stitch : Thank you. Reuters is reporting the NTSB chairman stated the systems designed to prevent a battery fire aboard a 787 did not work as intended. Did she
54 Kaiarahi : She
55 BoeEngr : My interpretation was simply a statement that it shouldn't have caught fire, but it did, so the preventative measures didn't work. When asked for spec
56 Post contains links Stitch : Thanks again. The Seattle Times just posted an article on the press conference and the details announced.
57 Post contains images KELPkid : Would not short circuiting fall under the category of "manufacturing defect?" I know that in laptop batteries, there are fuses (tiny pieces of metal)
58 Pihero : Thanks for the link, Stitch. The picture of the aft electronic bay is quite impressive. Basically nothing new for another week, iF I understand correc
59 Post contains images KELPkid : I'm thinking that in the JL incident, sitting on the ground might have contributed to the problem. Seems like the systems designed to ventilate smoke
60 Tristarsteve : Just been looking at a B787 Schematics manual. There are too many abbreviations!, but The Main battery is connected to a Hot battery bus. This is cha
61 tdscanuck : That was *the* reason there was smoke on the main deck. None of the smoke containment features will work properly with the ECS off and sitting on the
62 Post contains links kanban : While we've all heard or read the words from the press conf. here are some interesting pictures of the disassembly.. I think picture three has the sec
63 Post contains links nomadd22 : Not sure how seriously to take information from anonymous Japanese sources, but they're reporting that the charge controller was burnt up. I'm not cle
64 CM : Not surprising. The charge controller is a small circuit board which is integral to the battery. It is not the same thing as the battery charger itse
65 nomadd22 : Got it. That was probably the part that tracked status of individual cells then. If it had quit first, I'd have expected the system to default to a l
66 Post contains links kanban : Aviation Herald has some new pictures including a hole in an electrode http://avherald.com/h?article=45c377c5&opt=6144
67 Post contains links Kaiarahi : NTSB update from Jan 24 (slide presentation). There are some new photos / graphics. http://www.ntsb.gov/investigations/2...3/boeing_787/JAL_B-787_1-24
68 Kaiarahi : There's also a new NTSB twitter update: "The battery charging unit passed all significant tests and no anomalies were detected." So far we have: - evi
69 Pihero : Thanks for these posts, Kaiarahi. My git feelein has always been on manufacturing defects and / or quality control of the battery manufacurer. That do
70 Post contains links Aviaponcho : Pihero, http://batteryuniversity.com/learn/article/lithium_ion_safety_concerns If i'm reading correctly, no protection system can prevent a thermal ru
71 KC135Hydraulics : So are we saying that the NTSB may be incorrect in stating that Boeing's protection systems did not work correctly? What I've been reading in the last
72 kanban : That's the way it sounds to me.. And I'm not sure how one would design a protection system that would preclude the failure from an internal defect. R
73 Pihero : I really do not think that would be acceptable for any certifying authorityhowever dearly we would like to see the planes back in the air where they
74 WingedMigrator : I'm not sure if that helps... all it would do for you is reduce the size of the fire, and maybe provide battery function during and after the fire. B
75 nomadd22 : Thanks for finding that Kaiarahi. It answers just about all the questions I had about the design. Packing the cells like that surprises me a little, g
76 Kaiarahi : My first thoughts around the packing are that Li-Ion is mostly used (and designed) for consumer electronic applications, where space is at a premium.
77 Seat55A : I think one must expand the scope of thinking about fault protection, to include the Quality Control (and production quality engineering) of the cell
78 Post contains images KELPkid : Aluminum is most assuredly flammable. You haven't thrown beer cans into the camp fire? Granted, it doesn't go up like magnesium in your high school c
79 Deltal1011man : Just got to say thanks to CM for starting a thread that isn't full of trolls. Ha! Or, say never mind to those degrees, go and get and A&P and a bu
80 Post contains images sunrisevalley : Am I correct in my understanding that in the two incidents in question ( JL and ANA) the batteries had relatively low "hours" and that there are other
81 Stitch : The Ship's Battery on the NH bird was replaced in October. The airframe was delivered in January 2012, so that would make the original battery upward
82 tdscanuck : Although not totally inflammable, CFRP doesn't burn as well as aluminum. It's harder to light and takes longer to burn through. In virtually ever con
83 Seat55A : Is extended quality testing of 100% of articles really normal for any manufacturing process? That's far more than Quality Control. It expresses zero
84 Post contains links zanl188 : Todays NTSB update: January 27, 2013 WASHINGTON – The National Transportation Safety Board today released a fourth update on its investigation into
85 tdscanuck : For safety critical applications, it's absolutely normal. No. It's the reality that complicated assemblies with hundreds or thousands of components h
86 Seat55A : Is this code for "Boeing has a proposed fix and they need people to try and break it"?
87 Kaiarahi : Sounds to me that it's getting closer and closer to cell manufacturing defects (cue the shorted electrode), which are the cause of the majority of Li
88 HAWK21M : Anyone having the list of snags till date on the type. One Engine issue during test conditions. One Electrical fire during test conditions that was al
89 KC135Hydraulics : Quite a few generator failures in flight as well Hawk. Definitely on United and Qatar airlines, maybe others too.
90 Post contains images ferpe : I feel really sorry for the guys up northwest, the solution seems elusive.... Then it is good to know that one can always rely on our airline ground c
91 Post contains links canoecarrier : Good discussion here. I won't add much to the discussion and won't post other than this but as Kaiarahi mentioned the Civ-Av threads have become a sep
92 Post contains links Aviaponcho : Bonsoir, Tracking tweets I find this pdf from Airbus on Lithium batteries http://www.multimedia-support.net/fl...-safety-conference/docs/20-3-1.pdf
93 HAWK21M : I've heard the AI ones had Pack trip issues....
94 prebennorholm : I provided this link a week ago in the a.net GA forum. Maybe it made its way to Twitter from there??? Page #13 is interesting, especially: - Independ
95 okie : Lots of obvious things keep popping up that one would assume would be addressed long before now. There are a lot of systems on the 87 that are powered
96 tdscanuck : The VFD's "hide" behind the high voltage DC buses. The HVDC buses feed motor controllers that change the DC into appropriate frequency/voltage AC to
97 okie : Yes, I know, something I deal with everyday but larger drives with multiple 3,000+ amp DC busses. We deal with the harmonics issue with phasing trans
98 KC135Hydraulics : What is a VFD and what does it do?
99 okie : Varible Frequency Drive. Used to control speed and torque of a three phase electric motor. There are some exotic 5 and 11 phase out there but not inv
100 Aviaponcho : Sorry, I missed it I would have pointed the very same slide by the way !
101 Seat55A : Thinking about dirty power as a source of problems, do we know if the ground power sources and procedures have been checked out? One of the incidents
102 mham001 : What reaction could the charger have that would damage the separator without the BMS recording the event or being damaged itself? in the EV world, it
103 tdscanuck : You're really not going to like where they locate the engine computers... Tom.
104 okie : That is my point, if the SCR in the charger was firing it lets anything through as its gate signal firing angle is calculated off the end of the prev
105 JHwk : Been reading up and finally broke down and joined to post a question/comment. Really appreciate all the information people have shared and it is nice
106 tdscanuck : The battery chargers run off the 28VDC buses...I'm not an electrical guy but I can't see any reason the chargers would have SCRs. If the chargers are
107 Post contains links Seat55A : New York Times reports there was history of 787 battery issues at NH http://www.nytimes.com/2013/01/30/bu...battery-ills-before-the-fires.html Also on
108 JoeCanuck : Excellent thread...kudos all...keep it coming. There is a possibility that no precise cause of the fires will ever be found, or that the two fires wer
109 AirlineCritic : There was always (at least) two parts in the concern. The frequency of the events, and their treatment. Given that they now are saying multiple batter
110 Post contains links and images JoeCanuck : Here's something I found especially interesting in that PPrune thread. I'm a bit fuzzy on the protocol of posting from another board but I thought th
111 Post contains images Caryjack : I would be surprised if designers were still using SCRs in these types of switching power supplies when IGBTs have doing the job for at least 20 year
112 tdscanuck : My guess is yes, with the FAA agreeing that the risk of a high level event (loss of aircraft) is reduced to an acceptable risk while the NTSB screams
113 Litz : The Boston plane never got hooked up to ground power, and the other incident was airborne....
114 PITingres : I think Seat55A's suggestion was that something on the ground set the stage somehow for the ANA battery failure, but it took long enough to actually f
115 dalmd88 : The MD90 also has a wild freq system. I think it was the first one in a commercial jet. There were a ton of teething problems when it first came out,
116 Post contains links JoeCanuck : Logically, I find it heartening that the investigators are not jumping the gun and speculating about causes and effects, but emotionally, it sucks wai
117 Post contains links nomadd22 : It's not the only alternative. I'm going to cheat and copy a post from uncivil av. http://www.flightglobal.com/news/art...ttery-fundamentally-unsafe-
118 Post contains links rcair1 : I don't think it is so wild-eyed. Better individual isolation may be a useful idea. It would require a lot of certification testing tho. Depends upon
119 Post contains images KELPkid : Irregardless, the laptop solution is that there is a fuse in every battery cell, and if a short happens, the fuse blows. The battery is useless at th
120 JoeCanuck : Very true...I'm just going by what I have some experience with...and with what Cessna seems to have chosen for their CJ-4. Boeing, the manufacturers
121 Post contains links and images Starlionblue : It is quite large; much bigger than the 787 battery. Here's a pic of the 53kWh Tesla Roadster battery. The model S battery is up to 85kWh and even la
122 mham001 : I happen to have in my garage a pack of 8 LiFePo4's for 24v (25.6 nominal), 180Ah for an off-grid home. Dimension of the Huggy box they fit in so nic
123 JoeCanuck : Fantastic, thanks. My batteries have somewhat different properties. Mine actually have a higher rated voltage as well as nominal voltage, though the
124 Post contains links ferpe : It seems that B is having at least one path that may work and not require the long lead times of a new battery and changes to the electronics, also th
125 Aviaponcho : Hello Thank you all, JoeCanuck, mham001 Cessna had a 18 months homework for its not new (same technology) reinforced battery. In these 18 months, how
126 dynamicsguy : Regarding the choice of Tesla to use thousands of smaller cells: quite some time ago I went to a talk hosted by a guy from Tesla for a group of mostly
127 Pihero : Same article I just discovered on Leehamnet. The interesting excerpt : " Boeing CEO Jim McNerney did not talk about solutions, but said the company p
128 Stitch : As I understand it, the containment vessels for the four Li-Ion batteries on the A350XWB are directly vented to the outside so leaking electrolyte an
129 okie : Ok, but I am just not sure you can just bore a couple holes for the two battery vents in CRFP. Doable but would seem unusual to charge a battery need
130 Stitch : Sure you can. The plane has plenty of holes drilled into it for other things (potable water, fuel, sewage, air flow, etc.).
131 nomadd22 : I'd think the most you would need is a thick spot where you made the vent. Maybe nothing but the fitting if it's a low load spot. We use liquid acid
132 Aviaponcho : Hello Stitch The piping work will certainly be easy. But you must be sure that you won't vent smoke from the forward Avionic bay in air conditioning
133 strfyr51 : Boeing seems to be standing by the Lithium Ion battery for now but I think it's a lost cause. that battery is not ready for Commercial Airline use and
134 Stitch : The front EE bay already has an outflow vent for smoke and a drain plug for electrolyte and other liquids and they don't put material into the Pack S
135 nomadd22 : If they can mess with the container without screwing up certification, I wonder if they might be able to make it a few inches bigger in order to put b
136 Humanitarian : Agreed, and I think they just file an for an expedited STC or being the OEM, do they need to file an STC or just amend the type certificate?
137 tdscanuck : You can. And the lord said...let there be titanium doubler plates... If you mean *that* battery, the evidence seems to point that way. The evidence f
138 okie : The crumbs seem to be leading a trail back to the cell manufacturer from what I can see with the public information available. Whether it is a QC iss
139 kanban : probably another unanswerable question, however the other 48 planes out there, have the batteries been removed, are they being monitored.?.. will some
140 Aviaponcho : Thank you Stitch All right, but then can this vent still be use for venting the avionic bay ? You still need to vent the forward EE bay don't you ?
141 zeke : The cell inside a battery itself is a relatively simple chemical process, however it is integrated into a part that probably includes a housing, and
142 strfyr51 : Thales didn't build or design that particular Lithium Ion Battery, the Company is GS Yuasa out of Japan. They designed it for light weight and ease o
143 rwessel : The voltage per-cell is a function of chemistry. Something near 3.7V is normal for most of the Lithium Ion variations, just like 1.2V is normal for a
144 bradmovie : I'm wondering about using the APU battery for ground power and whether anything is different about battery monitoring and lockouts/shutdowns/safety pr
145 Stitch : I don't believe the APU battery is used to power anything other than the APU start. The Ship's Battery (the main battery under the flight deck) is th
146 dalmd88 : I also think this is true. Every other Boeing works this way. It is a redundancy factor. If you kill the ship battery you can still attempt to start
147 Tristarsteve : Not every! The B737-200 and 300 have a single battery that does both functions. The B737-400 had the option of a second battery. This was usually ded
148 gigneil : Cessna and Airbus are going to keep the Li batteries as well... its going to be fine. Its the fire and containment issue that's going to cause the ET
149 okie : I am aware that Thales out sourced the battery to GS Yuasa. The battery carries a Thales part number on every picture Okie has seen. I am back to the
150 KELPkid : Apparently, according to the Civ/Av discussion, the NTSB is now interested in the "Battery Contactors" and has focused the investigation in that direc
151 Caryjack : This is stupid. From all accounts the fuel supplying the fire would be contained and consumed before the airliner reached the water. Even if I'm wron
152 Post contains images Deltal1011man : Like it or not this is the future. Boeing will get it worked out. (Only way i see the NiCad talk is if we start looking at years when talking about t
153 Tristarsteve : Bit big for an aircraft! Biggest ones are about the size of your fist and weigh a kilogram. They are changed as an LRU and not opened up.
154 Seat55A : Wonder if the interest in the Contactors is just the next thing, or if it is specifically related to findings? I am having a hard time believing that
155 JoeCanuck : After doing some googling, I've discovered that Cessna is using Lithium Iron Phosphate batteries, not Lithium Cobalt, and it was using LiFePo4 batter
156 strfyr51 : Nothing more than large Relays, used to power the airplane from the batteries and facilitate charging TO the batteries from whatever charging source
157 Post contains images Caryjack : I was looking for something like "29.8 Vdc nominal with 125 mV full load ripple". I'm sure it's from 3 phase alternators so it's going to be fairly s
158 Litz : We used to toss lithium in water in chemistry class... "land in the ocean" now sounds like an even worse idea than before..
159 JoeCanuck : If you're landing in the ocean...you may have other things to worry about than burning batteries.
160 Post contains links kanban : per http://avherald.com/h?article=45c377c5&opt=6144 here is the latest JTSB addition On Feb 5th 2013 the JTSB released a second progress report in
161 Post contains links Kaiarahi : The equivalent photo of the JL battery is here http://www.ntsb.gov/investigations/2...3/boeing_787/JAL_B-787_1-24-13.pdf (slide 18).
162 KC135Hydraulics : So are we back to saying it might have been a battery manufacturing issue and not a problem specifically with the jet? Or perhaps higher than anticipa
163 Post contains links Seat55A : Boeing' is wanting test flights to get data on vibration and temperature change - possible working hypothesis on root cause is something about conden
164 rcair1 : Unlikely. Nobody can assure batteries cannot run away. The containment system must contain it. So if the FAA determines the issue is with containment
165 nomadd22 : It's not irrelevant when calculating overall odds of an event affecting safety.
166 kanban : Maybe a better way of putting it is: If a new containment system meets the FAA criteria and the planes are flying again, then Thales/Boeing/Yuasa can
167 HAWK21M : If Boeing plans a replacement Battery type to those used on its previous types,incur a load penalty, get the B787s flying & then work on a mod fo
168 Post contains links Kaiarahi : NTSB presentation and press release, Feb 7: http://www.ntsb.gov/investigations/2...13/boeing_787/JAL_B-787_2-7-13.pdf http://www.ntsb.gov/news/2013/13
169 strfyr51 : in thi statevthe 787's apu battery is used aqs welllas the main ships battery for ground towing operations so getting the airplane to the gate could
170 Post contains links AeroWesty : The video of the press conference is online now, too. I also posted this link in the CivAv thread, but know some no longer follow that thread. It's 4
171 Pihero : Letter from Leeham.net : FAA Authorizes 787 Test Flights by leehamnet Statement from Secretary LaHood and FAA Administrator Huerta: As part of our ong
172 kanban : I would read that as .. since they are using a test a/p, that they ensure these items have not be rearranged with testing and test equipment. I read
173 Stitch : Boeing evidently has some theories regarding vibration and moisture penetration within the battery enclosure and these items are some of those that w
174 RickNRoll : It is quite possible they were instructed to do so by their company in the event of any battery anomalies.
175 kanban : You missed the point. the statement being referred to is: "While airborne, the crew must continuously monitor the flight computer for battery related
176 RickNRoll : I was referring to the post by Pihero. The last sentence seems to me a bit harsh... unless the alerting / message / alerting levels and priority syste
177 sunrisevalley : Any ideas how long it will be before the FAA declare themselves as satisfied and tell the NTSB to f.... off ? Nothing that I have read suggests that t
178 strfyr51 : Well, It seems I'm right, the FAA just granted Boeing the right to conduct test flights for the Lithium Ion Batteries On the B787. Boeing should get t
179 ltbewr : My question is how these grounded 787's are being kept. I would assume there are procedures to cover engine openings, for example, but what is done sh
180 strfyr51 : most every airline has storage procedures for short mid and long term storage. (can't say all because I don't know) At United we continue the #1 and
181 Post contains images Caryjack : I hate to say it but as far as the 787 program is concerned, storing unflyable 787s is the one task where is Boeing the unchallenged expert. Thanks,
182 HAWK21M : The AMM has a listed of Storage and preservation checklist to be adhered too.This frequency can be a weekly , forthnightly,monthly,3 monthly,6 monthl
183 Post contains links kanban : here's an expansion on some of what they're looking into http://www.bloomberg.com/news/2013-0...-787-battery-probe.html?cmpid=yhoo http://finance.yaho
184 nomadd22 : I've had problems with carbon whiskers in rf filters. They were from contamination during manufacturing. I'm not familiar with the ones in lithium ba
185 okie : The 787 battery pack is 8 batteries in series with each battery having 6 cells in parallel. From what I understand and from looking at the pictures r
186 prebennorholm : This is not correct, even if it could look like that on the ANA battery. The Yuasa LVP65 cell has the an active internal unit which is almost one met
187 okie : The drawings, pictures, and CT scans show distintly 6 positive collectors and 6 negative collectors for each battery what is being called a cell. The
188 Post contains links Seat55A : I assume you are referring to the NTSB Jauary 24 presentation:in particular the diagram on page 12 http://www.ntsb.gov/investigations/2...3/boeing_78
189 nomadd22 : Even if you were right, the pictures only show six points total, which would be three parallel cells. And, you're not right. Those triangles are just
190 Post contains links prebennorholm : It seems to me that you are unaware that LVP65 is exactly the cell used on the 787. When reading this: http://www.s399157097.onlinehome.us/SpecSheets
191 okie : I started there but The pictures of 10 meter long electrodes has me confused with your one meter reference. Okie
192 strfyr51 : just read today that Boeing is re-designing the lithium Ion Battery to make each cell isolated in an attempt to isolate malfunctioning cells from othe
193 sweair : IMO Airbus has a choice that Boeing doesn't, they have not yet certified its batteries, why risk unnecessary hard certification when there is an easi
194 bonusonus : How big is the 787 battery? I'm calculating 8 cells * 65 amp-hr *27 V nominal = about 14kWh... does that sound correct?
195 Kaiarahi : I doubt it. Yuasa might be.
196 Post contains images KELPkid : I'm sure they *both* are. I'm pretty sure that any redesign of the battery to better contain a failure of the individual cells is going to make the b
197 prebennorholm : It sounds very incorrect. Nominal cell voltage is 3.7V, therefore 8 * 65Ah * 3.7V = 1.924kWh - or about 2kWh. A 14kWh battery would be a 500 lbs mons
198 kanban : I'm not sure the box is a Boeing design.. Boeing is providing the space envelope but the battery pack is a vendor designed LRU, whether that is a Tha
199 WingedMigrator : So an 85 kWh battery (such as is found in the Tesla Model S) would be a 6000 pound monster. Amazing.
200 nomadd22 : Interesting math. How do you get a battery 6 times the capacity weighing 12 times as much? As it is, the Tesla 85kwh pack runs about 1400 pounds. The
201 bonusonus : Thanks for the clarification. That makes more sense. Strangely, I read an article that states that typical energy drawdown to start an APU is 15kWh (
202 Post contains images prebennorholm : Each cell is 2,750g, so 8 cells without box etc. is exactly 22kg or 48lbs and 7oz. 76.9% is little more than half, so yes, you are right...
203 Post contains images WingedMigrator : Oops. Must have been stuck in octal. My apologies.
204 Post contains links and images Caryjack : From today's Seattle Times, which covers airline news of Boeing. http://seattletimes.com/html/busines...ology/2020373450_boeing787xml.html From the ar
205 Stitch : Boeing is also evidently looking into increasing the spacing between the batteries to improve cooling and to prevent short-circuits from cascading to
206 bellancacf : It's good to hear that those cells won't be pressed against each other (albeit with partition), as the recent diagram from Boeing makes it appear that
207 JoeCanuck : Through this entire ordeal, it's easy to forget, (except for the diehard tin hatters), that the crappy containment of the original batteries, actually
208 Stitch : I am of the opinion that the current batteries won't be in service by the end of the year unless it is definitively proven that the cause of both the
209 Post contains images KELPkid : Should be simple enough to test-build a ground mockup of both E&E bays, and intentionally short out a cell, and watch what happens Oh, and it woul
210 CALTECH : Think you have it right. It seems that on the 787, after takeoff, gear up or a few minutes pass and the MainBatteryRelay opens to isolate the Main Ba
211 rcair1 : I share this opinion - but I have no data to support it... BTW - the civ thread has gone seriously off into the weeds again... oh well.
212 okie : I am afraid you are correct. My guess at this point is that there is an issue with the battery cells themselves, either design or QC. In any case it
213 rcair1 : Nicely stated!
214 rcair1 : Couple of questions: - Can the RAT on the 787 start the APU? - Can the main battery on the 787 start the APU? - Are the 2 engines on the 787 (or any p
215 Stitch : No. It should, since it is the same battery as the APU battery. And when starting the APU via battery power, normal operation is to use both the Ship
216 Post contains links Stitch : Leeam.net notes that Boeing is likely following a similar path that Cessna has done for the lithium-ion batteries that are planned for use on Citation
217 bikerthai : And if Cessna has the patent on that technology, then win one for the little guy. Either ways, someone will get some nice royalty checks. bt
218 Post contains images okie : I am not sure anyone has a patent on a "battery incinerator box" I do not think the aircraft industry is going to lose the Li-ion battery. Just disap
219 JoeCanuck : I know...it seems odd that a root cause hasn't been exactly pinned down. I am a bit disappointed with how Boeing seems to have dealt with the issue o
220 nomadd22 : Just deleted a tirade against idiotic patents out of respect for CMs purpose for this thread. I don't think there's any realistic possibility of ensu
221 hivue : And an X% increase in battery, BMU, etc. complexity, right? Boeing may not have thought of an increased rate of battery replacement as "inconsequenti
222 Stitch : I expect it is because Boeing has money burning while those planes sit on the ground that they're moving with the most expedient way to satisfy the F
223 JoeCanuck : I have no doubts that Boeing is doing whatever it takes to get things back to normal the safest, most reliably way possible taking into consideration
224 Stitch : You do it through education and a damn good public relations campaign. I have to believe that a NiCad or Lead Acid battery can leak or catch fire, so
225 kalvado : So what happened to a swiss cheese model? If battery fire is now an expected nonevent condition, we are down to single (containment) failure being en
226 bikerthai : To be fair, it would require 1) A battery failure plus 2) Containment Failure 3) Fire detection and suppression failure 4) Airplane Structural or Fli
227 PITingres : If I understood previous postings correctly, if a situation like that truly existed, the design would not be certifiable. An on-board fire does not a
228 Post contains images KELPkid : And it seems that Boeing's hands are tied on that one...the FAA won't allow them to fly the current design around to try and figure that one out Abou
229 kalvado : 1. business as usual - at least many people on this forum are willing to believe in that. Something like a go-around, which is positively non-newswor
230 kalvado : It took only 1 event for the type to go from top to very bottom in terms of casualties per flight hour. Two airlines had to go long way to restore a
231 Post contains images Stitch : A failure of containment does not automatically lead to loss of the airframe - both NH692 and JL8 are proof of that. Concorde was withdrawn from serv
232 Post contains images KELPkid : Yes, but if the problems are being caused by things unique to the aircraft they occurred in, then Boeing shall never know in ZA005... No two aircraft
233 Post contains links zanl188 : Link to NTSBs interim report on the JAL incident: http://dms.ntsb.gov/pubdms/search/hi...D=54251&CFID=2871&CFTOKEN=67900912
234 Post contains images Stitch : If the issues are airframe-unique, then the FAA never should have grounded the fleet since only certain frames would be susceptible to this issue and
235 Stitch : So reviewing the latest NTSB interim update, at 1021:15 the EICAS reported the APU battery failed. However, the APU continued to run until 1021:37 whe
236 Post contains images KELPkid : So, when did the cleaning crew note the smoke and alert the ARFF guys? Sorry, at work, and way too busy to look at the "War and Peace" sized NTSB rep
237 RickNRoll : Given that we don't know yet if it is or isn't, then surely we have to find out. There is only one way to find out, flying a plane that has not had t
238 Post contains links 777ER : Next thread is here: B787 Grounding: Tech/ops Thread Part 2 (by 777ER Mar 9 2013 in Tech Ops) All posts made after this post will be deleted for house
Top Of Page
Forum Index

This topic is archived and can not be replied to any more.

Printer friendly format

Similar topics:More similar topics...
Tech/ops Glossary Of Terms/equipment :) posted Sun Mar 24 2002 00:07:23 by EGGD
What Does All Of This Equipment Do On The 787? posted Tue Jul 20 2010 07:10:03 by c5load
Boss Of Delta Tech Ops posted Sat Apr 21 2007 23:56:05 by Ma2mw
DL Conversion Of The 764ER To Int. Ops posted Thu Feb 9 2006 17:13:56 by Fanoftristars
Old Photo Of DC-10: Tech/ops Question posted Wed Jun 22 2005 16:38:12 by September11
To My Friends In The Tech/ops Forum... posted Wed Jan 29 2003 20:35:36 by NormalSpeed
Idea For The Tech/ops Forum... posted Sat Feb 23 2002 09:53:51 by EGGD
Load Factors On Each Day Of The Week posted Sun Jan 6 2013 09:44:51 by Evan767
What Is FWD Of The O2 Mask? - KLM 737 posted Sun Dec 9 2012 12:46:34 by barney captain
Landing Gear Length On The 787-10 Inadequate? posted Fri Nov 16 2012 16:35:34 by Max Q