FAA Grounds 787s

[TeachMe]

SLF question,

On long flights I often plug in my laptop as the battery is not good for more than say 5 hours tops. If the charging of Li-ion batteries is a significant risk factor, why am I allowed to plug in my laptop in flight? Surely a discharging battery is safer than one that is floating? Has the attidude to Li-ion batteries in flight thus been a bit too commercial driven (reduce weight / make us SLF happy) than safety driven?

[Speed of Sound]

The charging/maintenance set-up for a laptop battery is tried and tested technology.

Even when Sony recalled the batteries for the old Apple Powerbook, there had only been two of them known to catch fire in use, out of something like 22 million of them installed.

(and thanks to BOAC for that link)

[Lyman]

Howdy glenbrook....

you write....

In the medium term, we may need to accept a higher risk that batteries occasionally catch fire, perhaps in the same way that we accept that engines do.

That ship has sailed, in the form of what was essentially a "waiver" of the concern you discuss, in the form of consideration for allowing the LiIon technology aboard in the first place....

The list of special considerations has been posted elsewhere, and shows that most of the defining limits of the waiver were exceeded (violated) in the first incident JAL.

In allowing the technology, FAA has also restricted its use, there is no possibility this new technology will ever be allowed to attain the waiver given, say, A modern TURBOFAN, which in including its use on modern aircraft, assumes that an "UNCONTAINED EVENT" need not be demonstrated to be mitigable...

There are other technologies, that make the continuing use of LITHIUM ION not exclusive....

The waiver by FAA in itself cannot be discarded, to do so is to admit that LiION is exclusive, the only way to provide standby power, and that is not the case.

Your comment is thought provoking, in that if Boeing can demonstrate that LiION is critical for the Dreamliner, a special waiver can be granted, the basis for such a determination would end up being perhaps an economic one, even a survival one for the airframer.

That is what the FAA did, whether the waiver is type specific or becomes the new standard is not known. Boeing have painted everyone into a corner.

Will it come down to "NOTICE of proposed rulemaking"? That will be an interesting PUBLIC HEARING......

imo

[G&T ice n slice]

So.... you are suggesting that they'll change the rules?

That's a bit unlikely isn;t it?

oh ... wait... who got the rules changed so that twins could operate where previously only quads could go...

silly me!

[deefer dog]

I'm sure that when these batteries were first mentioned, or even considered for the aircraft at the drawing board stage, eyebrows will have risen. It would be interesting to read the paper chain that then followed, those for and against, and either from the FAA, designers, battery makers etc etc.

I'll bet the farm that someone is already saying "I warned you," and I bet they have the email to prove it. I feel sorry for the recipient/s.

[toffeez]

I don't believe Boeing will go for a technically weak fix, one which will only pass the FAA after a few more free lunches.
They often appear dumb and clumsy, but behind the scenes they know they were very lucky to have these events now.
It's one thing to have an accident no-one could foresee, but losing a plane after these clear warnings would be unforgivable.
They will find a robust fix even if it costs a hundred or so kgs. And thank their lucky fairies they're not now searching the Pacific.

deefer, add ALPA to your list. They made a lot of (published) comments when the FAA's Special Conditions were being formulated.

[Taunusflyer]

@TU.114: The marks at the fuselage seems to come out of a valve/vent, good to see in this picture, direct under the first "7" of JA804A: http://img.planespotters.net/photo/247000/original/JA804A-All-Nippon-Airways-Boeing-787-8-Dreamliner_PlanespottersNet_247964.jpg

At the 1st look I also thought about a burnt through fuselage.

[Speed of Sound]

I'll bet the farm that someone is already saying "I warned you," and I bet they have the email to prove it. I feel sorry for the recipient/s.

Slightly off topic but a close friend of mine was heavily involved in the Millennium Dome project and as it got ever closer to Dec 31st 1999, panic set in and all sorts of technical and safety rules and regulations went out the window as well as some of the financial control.

She is convinced that one day there will be a proper audit of what happened and she has copies of 15,000+ e-mails on a hard drive somewhere just in case.

Some of these e-mails actually say "You do know that what you are proposing is actually illegal, don't you?" :ugh:

SoS

[Machaca]

The photo of the forward EE bay venturi vent port taped up with plastic is confusing. The battery is not adjacent to the port, and no damage to the hull occurred. Here's a shot that shows the port worked as designed:

http://i337.photobucket.com/albums/n385/motidog/ANAbatt09_zps7de0a00d.jpg

Adding some images to help understand locations:

http://i337.photobucket.com/albums/n385/motidog/ANAbatt804_zps31486855.jpg

http://i337.photobucket.com/albums/n385/motidog/787fwdEEbayVenturi3.jpg

The forward EE rack is centered in the barrel just aft of the nose gear support structure, and upon completion is walled off from the cargo hold.

[Machaca]

Pedantic comparisons between inexpensive mass produced batteries (over 2 billion mobile devices, laptops and tablets sold in 2012) and the 787 batteries is as foolish as equating the map application on your smartphone to the Honeywell navigation package on the 787.

[Chris Scott]

Quotes from Machaca:

(1)"The photo of the forward EE bay venturi vent port taped up with plastic is confusing."

Yes, it was. Thanks for the new pic, which I had searched for in vain! (The "smudge" from the port shows the airflow direction nicely.)

(2) "The battery is not adjacent to the port, and no damage to the hull occurred."

Depends what you mean by "adjacent"? The forward bay seems to be fairly small, judging from this location diagram (http://www.pprune.org/tech-log/505695-787-batteries-chargers.html#post7643262), and the BAT is at the L/H end, close to the fuselage skin. But the diagram makes it hard to see if the bay is forward or aft of Cabin Door 1L.

The original photo seems to show the plastic-covered port as being just below the first "7" 0f the "787" painted on the L/H side of the fuselage of this particular a/c (ANA seem to have several liveries for their B787s). Here's a link to a photo of an a/c in the same colour scheme (http://homepage2.nifty.com/good_day_itm/ana787.html). It suggests that the port is therefore just aft of Door 1L (and, of course, well below it). Here's the link to the article with the close-up photo of the port (http://news.sky.com/story/1040689/dreamliner-fire-investigation-widened).

So, is the port aft of the bay, or adjacent to it?

[grebllaw123d]

Chris Scott,

I think that the port is placed adjacent to the bay - far aft in the bay on the L/H side.

I wonder what function it has - looks just like a hole in the skin? Or is it a venturi?
Vent for the battery?

[Chris Scott]

grebllaw123d,

Not sure yet, but here's a link to a very good photo (http://haru-setsuyaku.com/wordpress/archives/1139) of the L/H forward fuselage of a/c 811, which has the same colour scheme as the incident a/c 804. (See the second B787 photo on this link.)

The port is just below the first "7" of "787". It doesn't look very venturi-like, so might be a drain hole. (There seems to be a large venturi well below it, almost behind the nose leg.)

[DozyWannabe]

Pedantic comparisons between inexpensive mass produced batteries (over 2 billion mobile devices, laptops and tablets sold in 2012) and the 787 batteries is as foolish as equating the map application on your smartphone to the Honeywell navigation package on the 787.

Well, quite! :ok:

Aviation-grade batteries will have to pass far more stringent regulations and certification requirements than their consumer-grade equivalents - it goes with the territory. Obviously, being a relatively new technology as far as aviation use is concerned, some of these requirements will probably need to be tightened as more real-world use cases highlight potential issues.

Talk of lead-acid (and probably even NiMH) technologies ignores the fact that
they cannot supply the required juice for the systems.

@TeachMe : If I recall correctly, the problems with consumer battery fires were traced to a combination of a sub-standard batch of the batteries themselves with poorly-made mains chargers. Are you using the mains charger when flying (I'd be surprised) or another device?

[peter we]

Pedantic comparisons between inexpensive mass produced batteries (over 2 billion mobile devices, laptops and tablets sold in 2012) and the 787 batteries is as foolish as equating the map application on your smartphone to the Honeywell navigation package on the 787.

The difference is that 'cheap' mass produced batteries and chargers are about a million times less likely to result in a battery fire than a 787 battery.

The 787 battery/electrically system has a statistically proven chance of failure every 25,000 hours. 3 years. That sort of reliability in consumer devices would see multiple daily phone/laptop fires in a office building of a 1000 people.

In the Uk there would be around 30million battery fires per year, every night would be like the Blitz, except with fires all around the country.

The acceptable level of risk is one in a billion flight hours, not one in 25,000

[grebllaw123d]

DozyWannabe,

You wrote:

"Obviously, being a relatively new technology as far as aviation use is concerned, some of these requirements will probably need to be tightened as more real-world use cases highlight potential issues."

You are so right - I would even omit "probably"!

You then say that other battery technologies cannot supply enough juice required for the systems.
This is not quite correct.

An example:
On the A340 we had 2 main batteries (NiCd as far as I remember) each with 37 Ah - makes a total of 74 Ah. The Boeing 787 has 1 main battery with 65 Ah.
We had an APU battery with 37 Ah - the BOEING 787 uses the same APU battery as the main battery, i.e. 65 Ah - quite a big battery just for APU starting and a few lights.

So enough power with the "old" battery tecnology, but with penalties in space and weight - double up I guess.

[DozyWannabe]

Fair enough, perhaps I should have qualified my statement with "enough juice per unit of mass".

[kilomikedelta]

Peter We, I think you are looking at it from the wrong point of view. Boeing is a marketing company not an engineering company. Saving weight with lithium cobalt dioxide batteries packed cheek by jowl saves space for more marketable and fee generating cargo and slf amenities which contribute to shareholder value. The stock market forgets much more quickly than the families of a few dead passengers.

[Lyman]

http://www.gpo.gov/fdsys/pkg/FR-2007-04-30/pdf/E7-8186.pdf


Read this. After a read, you will grasp the scope and letter of the standards set for Lithium Ion operation aboard the 787.

With a reasonable understanding of the events and the recent commentary, here and elsewhere, it will be impossible to continue to accuse the FAA of jumping the gun, nor will any attempt to defend continued operation without major changes be a reasonable position.

The aircraft failed in most, and (will after further investigation) likely all of the criteria. Withut changing the entire engineering approach to the rules, relative to standby power, the 787, without compliance, effectively has no type certificate.

But that is OK, what is needed now is for Boeing to implement their PLAN B.

There is no chance that, knowing the Lithium chemistry was not a lock, Boeing has nothing ready to refit.

In corporate domain, those who cannot parse the difference between confidence and hubris, fare not well.

short form....

The Proposed Special Conditions
Accordingly, the Administrator of the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for the Boeing Model 787–8 airplane.
In lieu of the requirements of 14 CFR 25.1353(c)(1) through (c)(4), the following special conditions apply. Lithium ion batteries on the Boeing Model 787–8 airplane must be designed and installed as follows:
(1) Safe cell temperatures and pressures must be maintained during any foreseeable charging or discharging condition and during any failure of the charging or battery monitoring system not shown to be extremely remote. The lithium ion battery installation must preclude explosion in the event of those failures.
(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.
(3) No explosive or toxic gases emitted by any lithium ion battery in normal operation, or as the result of any failure of the battery charging system, monitoring system, or battery installation not shown to be extremely remote, may accumulate in hazardous quantities within the airplane.
(4) Installations of lithium ion batteries must meet the requirements of 14 CFR 25.863(a) through (d).
(5) No corrosive fluids or gases that may escape from any lithium ion battery may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition, in accordance with 14 CFR 25.1309(b) and applicable regulatory guidance.
(6) Each lithium ion battery installation must have provisions to prevent any hazardous effect on structure or essential systems caused by the maximum amount of heat the battery can generate during a short circuit of the battery or of its individual cells.
(7) Lithium ion battery installations must have a system to control the charging rate of the battery automatically, so as to prevent battery overheating or overcharging, and,
(i) A battery temperature sensing and over- temperature warning system with a means for automatically disconnecting the battery from its charging source in the event of an over- temperature condition, or,
(ii) A battery failure sensing and warning system with a means for automatically disconnecting the battery from its charging source in the event of battery failure.
(8) Any lithium ion battery installation whose function is required for safe operation of the airplane must incorporate a monitoring and warning feature that will provide an indication to the appropriate flight crewmembers whenever the state-of-charge of the batteries has fallen below levels considered acceptable for dispatch of the airplane.
(9) The Instructions for Continued Airworthiness required by 14 CFR 25.1529 must contain maintenance requirements for measurements of battery capacity at appropriate intervals to ensure that batteries whose function is required for safe operation of the airplane will perform their intended function as long as the battery is installed in the airplane. The Instructions for Continued Airworthiness must also contain procedures for the maintenance of lithium ion batteries in spares storage to prevent the replacement of batteries whose function is required for safe operation of the airplane with batteries that have experienced degraded charge retention ability or other damage due to prolonged storage at a low state of charge.
Note: These special conditions are not intended to replace 14 CFR 25.1353(c) in the certification basis of the Boeing 787–8 airplane. These special conditions apply only to lithium ion batteries and their installations. The requirements of 14 CFR 25.1353(c) remain in effect for batteries and battery installations of the Boeing 787–8 airplane that do not use lithium ion batteries

PLAN B is the last sentence. So it becomes, as an airframer, how does Boeing feel about doing all the legwork to make Lithium Ion batteries acceptable to the regulator, including Airbus, (EASA) versus falling back to the existing rules.....14CFR 25.1353(c).

[WHBM]

There was an old adage that the best airliner would be designed by Lockheed, built by Boeing, and with Sales & Marketing by McDonnell Douglas.

Somewhere along the way Lockheed pulled out of commercial aircraft, while McDD pushed the profitability desire too far, didn't come up with much innovative, and priced it too high anyway, so production plummeted and they got absorbed by Boeing. Unfortunately some McDD executive attitudes came with the merger (those in the know may care to insert some individuals here) into the combined organisation, where from about the turn of the century it became the smart thing at the exec level to champion outsourcing everything while downplaying all those experienced in-house engineers who seemed so expensive. And thus they outsourced the future of the company to a whole string of lowest-bidders, with all that entails. Moving the exec offices from the city where they assemble their products to one 1,500 miles away didn't help.

We've already had the major fiasco of the fuselage production issues, which seriously delayed the production, and now the battery system which appears, somewhere along its own chain, unfit for purpose. Of course, if all that Boeing engineers' experience had not been got rid of, things might be a little different.

All this public talk of the battery manufacturer, the circuit manufacturer, and so on is not actually relevant to the purchasers of the aircraft, or indeed to others. This aircraft was built and sold by Boeing, they are the company that the airlines have the contractural arrangement with, they are responsible for integrating all their outsourcers, they are the ones responsible for the certification with the authorities, and they are the ones who receive the cash from their customers - or not, at the moment. One day I trust that Boeing will fully wake up to this.

[glenbrook]

Hi Lyman,

But that is OK, what is needed now is for Boeing to implement their PLAN B.

There is no chance that, knowing the Lithium chemistry was not a lock, Boeing has nothing ready to refit.
I would like to believe that, but I am not sure that plan B is all that simple.
Maybe you are right, perhaps they have a non-Lithium-ion replacement that will fit the slot. But if they do, it is going to be 4 times heavier and twice the volume. Even if they have another Lithium-ion battery on the drawing board, it is going to take some time before it is ready to go. I could be wrong, engineers are at their most creative under pressure.

But perhaps there is a way out for Boeing. I am sure the engineers will find some issue responsible for starting these fires. This will be fixed across the fleet, but it still leaves Boeing with a battery which is flammable. Even if it is much less likely to catch fire, it still can't be certified. After fixing the initial flaw perhaps a compromise can be arranged with the FAA. Boeing would propose a battery redesign and promise to fit the new units within a limited time period, say 6 months. The 787 would be allowed fly again during this period which would give Boeing enough time to build, test and certify the new battery.

[HalloweenJack]

@Lyman


are you saying that the FAA , by following its own rules MUST withdraw type certification for the 787 , thus rendering it `unairworthy` until either the Li-Ion batteries are replaced , or an acceptable engineering *within the rules* solution is found?


will they genuinely ground the type for that potential length of time?

[DozyWannabe]

There was an old adage that the best airliner would be designed by Lockheed, built by Boeing, and with Sales & Marketing by McDonnell Douglas.

Cheeky aside - I'd amend that to "designed by Lockheed, BAC or Hawker-Siddeley", because truth be told a lot of the innovation came from this side of the pond - Lockheed themselves tacitly acknowledged this when they hired ex-HS avionics engineers for the TriStar. Unfortunately for them they seemed to inherit our tendency to have production difficulties at the same time... :E

[sb_sfo]

Glenbrook,
I hope you're right, but can you imagine which bureaucrat at the FAA, having been "burned" twice now, is going to sign off on what you propose?

That would take giant brass ones, even if they believed the Boeing spin.

[Lyman]

glenbrook

It is a frame, within which there is regulatory, economic, and engineering wiggle room.

The hope is that the current problem is related to the Manganese, the addition of which, though approved, may be the weak link, and Cobalt Oxide may be the default solution. The rules were published in April 2007, almost six years ago, so Boeing have some, [I]some[I] latitude. Abandoning LithIon would be a complete nightmare, but at this point, FAA has no room to be flexible, there is not a soul in the biz who wouldn't be ready to accuse the administration of special treatment. With such an open ended and potentially catastrophic issue of safety, Boeing has to decide how much to invest in the "new standard" (LithIon) for the industry. It would be off ledger, since it doesn't correlate to the original certificate.




HalloweenJack....

Yep, if FAA gets dug in, the certificate can be continued only with Ni batteries, or a bulletproof presentation of LithIon as the standard of safety. All "leniency" is over, done...If FAA get soft, and there is a problem, an accident, woe be tide....

[DozyWannabe]

I hope you're right, but can you imagine which bureaucrat at the FAA, having been "burned" twice now, is going to sign off on what you propose?

That would take giant brass ones, even if they believed the Boeing spin.

They're not going to sign anything off without sufficient proof - it's unlikely that they ever did, it just so happens that the lab-based certification tests failed to cover some of the eventualities in real-world operation. The issue here is that we're dealing with a type that has introduced a lot of new technology in one go and that is always going to have a higher risk of these "teething" issues. I'm certain both Boeing and the FAA were well aware of that going into this, and I'm equally certain that all parties involved will have laid out contingency plans to deal with the situation well in advance.

Any "spin" - as you put it - will be directed at investors and customers, not the regulators.

[peter we]

The APU is required for the ETOPS certification, which by definition has to be very reliable and therefore needs a very reliable battery.

I can see that this is going to be a long process.

[ozaub]

Please mods stop reposting of the li-ion special conditions. I listed them days ago back at #111. And no, 787 does not comply with it's special certification conditions so it must not fly

[Carbon Hybrid]

787 Battery

Include what you BELIEVE really caused the problem:
During battery operation, lithium at the negative electrode gives up electrons to become Li+, which dissolves into the electrolyte. This process is reversed during the recharge cycle, but the replated lithium adds unevenly to the electrode surface, and as the battery is charged and discharged, dendrites grow from the surface, which can cause short-circuiting in the battery and lead to explosions.

REALLY caused the problem:
Most of the batteries will pass all tests. During the manufacturing of the cells the annealing process has to be monitored Microscopically. Contamination or lack of proper cooling creates a Dendritic Structure.

And what can be done to prevent a recurrence:
Quality Control. Environment in manufacturing process.

OR correct the situation:
Work together!
:8

[DozyWannabe]

The APU is required for the ETOPS certification, which by definition has to be very reliable and therefore needs a very reliable battery.

Remember that the business case for the B787 was predicated on an increase in "point-to-point" journeys as compared to the traditional "hub-and-spoke" system. As such, it does not - at least initially - require ETOPS certification as it can fulfil that business case via intra-continental routes.

[poorjohn]

glenbrook: I would like to believe that, but I am not sure that plan B is all that simple.
Maybe you are right, perhaps they have a non-Lithium-ion replacement that will fit the slot. But if they do, it is going to be 4 times heavier and twice the volume
Do I incorrectly recall that the battery weighs some 65 lbs? Adding another 200 lbs doesn't seem significant. (Guessing that the APU battery was identical to the Main for spares commonality, I've not multiplied by two.)

I do think that lithium batteries do have other advantages e.g. low internal resistance that might make replacing them more than simply a weight-and-volume issue, though.

[glenbrook]

Remember that the business case for the B787 was predicated on an increase in "point-to-point" journeys as compared to the traditional "hub-and-spoke" system. As such, it does not - at least initially - require ETOPS certification as it can fulfil that business case via intra-continental routes.

Boeing have 800 orders to fill for a 330-minute ETOPS certified aircraft. A 787 without ETOPS is still grounded. Would Boeing even be able to deliver them?

[DozyWannabe]

Do I incorrectly recall that the battery weighs some 65 lbs? Adding another 200 lbs doesn't seem significant.

It's significant in that the aircraft was sold on the basis of fuel economy figures that have thus far proven optimistic even with the lightweight battery configuration.

Boeing have 800 orders to fill for a 330-minute ETOPS certified aircraft.

Which I'm sure it will be once the issues have been ironed out.

A 787 without ETOPS is still grounded. Would Boeing even be able to deliver them?

It's grounded at the moment with or without ETOPS, for sure. At this point, nobody outside of Boeing knows precisely what contingency plan is in effect or what that plan constitutes. It goes without saying that the airframes can be ferried without ETOPS - the limitations would only apply in fare-paying service.

[Willie Everlearn]

The history of Lithium Ion batteries is not very flattering and their adverse effects in aircraft not that reassuring despite some positive characteristics.
If I might point to the volatility of these batteries whilst adding I acknowledge they were NOT connected to an electrical system at the time, they did bring down a B747-400 in Dubai in recent times.
Were lessons NOT learnt?

Is their lightness of weight, their ability to quickly recharge despite the residual heat they omit with such potential for disaster truly worth it?
Apparently.

This is what we get when manufacturers are pressurized by an industry that is so driven by the bottom line.

That's not news but that too is reality.

Willie :eek:

[dunwawry]

I don't think it has been pointed out, but the power distribution and charging circuits seem to be made by Thales:
Actually Securaplane in the U.S. is making the Battery Charging Unit and doing the testing for Thales.
The batteries themselves are being made by Yuasa in Japan.

[DozyWannabe]

they did bring down a B747-400 in Dubai in recent times.

Did they? The FAA released a precautionary bulletin and restriction on carrying consumer-grade Li-ion batteries following UPS006, but as far as I know there has been no confirmation that the batteries were the cause of the fire...

[lomapaseo]

The acceptable level of risk is one in a billion flight hours, not one in 25,000

Define what you mean by "risk"

I have yet to see what evidence applies in this case to the level of risk (either regulated by statue or to somebody's concept of safety).

All this re-quoting of the Special Condition is meaningless and pedantic unless expert assessments follow of what paragraphs were not met. In the end the means to unground will be made by corrective actions that bring it back into specific paragraph compliance and/or equivalent safety actions.

Neither the completion of these assessments has been made nor the proposed means of compliance, This then is the thorn that produces the delay and feeds the rampant uneducated discussions on the internet boards

[Desert Dawg]

@lomapaseo

I would like to meet you and shake your hand. Your last line in your post is spot on! Well said!

[TURIN]

Since when has it been an ETOPS requirement to have a serviceable APU? Or is the 787 different due to it's reliance on electrical systems?

[TURIN]

The batteries are likely to be interchangeable to increase despatch reliability. (oh the irony!)
IE. If you have a main battery (or charger) go u/s away from main base then swap with the APU battery and away you go. MEL 49-1 refers.

[Sober Lark]

Although familiar with the long list of early in service problems with the 787, I'm finding it difficult to understand why the aircraft had to be grounded by the FAA rather than pilots or their representative bodies taking the initiative and refusing to fly them first.

[glad rag]

Turin, that's quite a MEL entry.

Bit like the one for purging system for the fuel tanks and allows it to be inop for how long??

Sound a bit F35'ish tbh.

[Swiss Cheese]

I was quietly amazed that the FAA grounded the 787, which of course was followed too by EASA (Can I hear EADS applauding in the background) . I was in shorts the last time the FAA grounded an airliner (DC-10 I recall) in the mid 1970s.

I have been critical of the FAA and EASA before for not grounding other aircraft when lives have been lost in highly dubious circumstances (Rudder PCUs in Boeing 737s, and ADIRU/Pitot problems in Airbus A330s).

I wonder what has changed the approach of the FAA, unless there really is something that bad with the 787....

[DaveReidUK]

Adding another 200 lbs doesn't seem significant.Adding 200lbs to the OEW of any commercial airliner, even one as large as the 787, is hugely significant.

Not so much for the impact on fuel burn, though it doesn't help, but for the effect on payload and therefore revenue potential over the life of the aircraft.

OTOH, if that's the price that has to be paid to get the type back in the air (and I suspect it will be) then that's what will happen.

[toffeez]

Adding 200lbs to the OEW of a commercial airliner is not hugely significant.

200lb on the OEW equals 200lb off the payload, and only if the latter is already limited for some reason.

This means no revenue loss on almost all flights, and 200lb less cargo revenue on the remaining few.

[BOAC]

Since when has it been an ETOPS requirement - it was in my company in 2008 for 737NG. Required to be started before entry into ETOPS area.

[vaschandi]

Interval: C
Installed: 1
Required: 0

May be inoperative or removed
a) VFSG systems operate normally
b) ETOPS beyond 180 minutes not conducted

[Romulus]

Adding 200lbs to the OEW of a commercial airliner is not hugely significant.

Quite possibly. But only if you know exactly where to add it at the time. If you allow the battery system 200lbs more who else do you give extra weight allowance to in your design budget? Give it to 9 others and you have a 2000lb weight problem.

Hindsight is a wonderful thing, helps make all sorts of decisions easy to make. Only problem is it's a bit late by then...

[hetfield]

Let's assume the 200lb additional weight of NiCd batteries instead of LiIon are realistic, IMHO the trade of for extremely more safety is out of question.

[cod liver oil]

The APU is required for the ETOPS certification, which by definition has to be very reliable and therefore needs a very reliable battery.

Power source for B787 APU starting may be airplane battery, a ground power source, or an engine-driven generator.

Wouldn't engine-driven generator be used as primary power source for APU in-flight lightup?

[Lyman]

And the 787 has two genset per side. That means at least two will be available, plus the RAT. When is 'redundant' beyond the pale?

Did Boeing 'miss' pushing for elimination of the standby power rule? Could they simply apply for offline Battery? Did they bite off a bit much in 'sampling' Lithium technology? Or did FAA deny such a proposal?

If batt is standby, why can't it be isolated in flight, even thirty minutes prior to and post flight?

ANA and JAL problems happened at TO and post parking. This problem may not be as critical as it might have seemed....

"INERTING" the batteries as part of the solution? It does say "STANDBY" in the regs.

Maybe someone who is not "uneducated" could respond?

[DaveReidUK]

Adding 200lbs to the OEW of a commercial airliner is not hugely significant.I suspect you have never sat on either side of the table in an airline/manufacturer negotiation, or indeed in a design review meeting.

Weight always comes at a cost.

[Lyman]

Absolutely. 200 Pounds is a seat. The argument will not be, "You will not have a full aircraft every time, so we'll just discount its elimination..."

It will be, "That seat is five hundred dollars iost in revenue per leg."

"And that is two hundred thousand dollars every year...." conservatively...

:ok:

[harpf]

All MC (small) batteries are made in China, Larger batteries(Car, Truck) are still made in the USA

[harpf]

x 20 years 2M/200 rule of thumb, serveral $1,000 per / pound is what will be paid to get a pound out of a large aircarft (per aircarft). Or 1M could invested in engieering, to get a pound out of new deisgn were several K will be produced. So if 200 pounds of batteries = 50M in egeering and 10K per aircraft is no brainer to go for it.

[toffeez]

"I suspect you have never sat on either side of the table in an airline/manufacturer negotiation"

I did exactly that for several years.

[Golf-Sierra]

Is there someone her more knowledgeable who might be able to answer this question:

Is it usually the case that there is just one type of battery fitted across a particular type of airliner? Would this differ by version (i.e. also say a -800 vs. a -900) and by customer spec?

What I am driving at is that it would be very shortsighted of the manufacturer to build a charger compatible with only one specific battery type - be it chemistry or capacity. So perhaps retrofitting a different type of battery as an interim measure with weight penalty is a straightforward option?

I presume what Boeing is struggling to do at the moment is work out what actually did go wrong as the issue might not be in the battery itself.

[WHBM]

Absolutely. 200 Pounds is a seat. The argument will not be, "You will not have a full aircraft every time, so we'll just discount its elimination..."

It will be, "That seat is five hundred dollars iost in revenue per leg."

"And that is two hundred thousand dollars every year...." conservatively...

Indeed. But that's just a negotiating ploy, which, presuming Boeing do have some aeronautical professionalism left, they should be able to competently rebut. Of course, the manufacturers have only themselves to thank for this perception that seat-mile costs are the be-all and end-all of life, as if every seat on every flight 24x365 can be filled with revenue pax at full fare (and, following on with the Boeing 787 marketing guff, as if there is no potential market any more for anything under 7,000 miles range - I wonder what they make of All Nippon using their 787s on domestic flights !)

[toffeez]

Between October 2005 and August 2008 the Manufacturer's Empty Weight of the 787-8 increased by 12500 lb.

[DaveReidUK]

the manufacturers have only themselves to thank for this perception that seat-mile costs are the be-all and end-all of lifeI've never come across an airline that laboured under that misapprehension. If they did, they would all be flying A380s.:O There are some circumstances when SMC is the most relevant metric, and other circumstances where aircraft-mile cost matters more.

That said, almost all airlines calculate their yield on a seat-mile/passenger mile basis.

[Jando]

... I'm finding it difficult to understand why the aircraft had to be grounded by the FAA rather than pilots or their representative bodies taking the initiative and refusing to fly them first.

Please note that - although many posters here only talk about the FAA - half the fleet was already grounded by their respective operators before the FAA grounded it.

[Sober Lark]

Thank you Jando

[Temp Spike]

What's the big deal with this Lithium-Ion battery? Don’t they have a Liquid Ni-Cad certified to replace it? Type Certificate Data Sheets? What a dumb idea to utilize a new concept battery without a ready replacement.

TCDS - T000215E

Lit Bat - Special Conditions - 25-359-SC

Any Body have 25-359-SC details?
I can't find it.

[Chris Scott]

Quote from cod liver oil:

“Power source for B787 APU starting may be airplane battery, a ground power source, or an engine-driven generator.
Wouldn't engine-driven generator be used as primary power source for APU in-flight lightup?”

Probably not. I cannot quote the ETOPS/EROPS requirements, but suspect one of the scenarios they address is likely to be that of complete electrical-generation failure. That MAY mean that the ability to start the APU is mandatory for some or all ETOPS legs. I doubt it would be acceptable to rely on the RAT and its limited generation capability to provide essential services for several hours (although I stand to be corrected).

However, as an interim measure, it might be acceptable to start the APU as a pre-emptive measure prior to commencing the part of the sector where the ETOPS rules apply. If the APU failed to start (due to cold-soak, or whatever), you would have to divert somewhere. So it might make sense to leave it running on departure (off-load), and not shut it down until the ETOPS leg has been completed. The fuel-flow on an idle APU at high altitude is relatively modest.

FOOTNOTE
Wouldn't it be nice to have full schematics of the B787 electrical systems in the public domain, nearly 18 months after this civil aircraft entered service? In April 1988, when we started airline ops on the cutting-edge A320, no one put any pressure on line pilots to treat the contents of the FCOM as sensitive commercial information. Why is Boeing so shy of divulging its engineering achievements?
In the present circumstances, public rumour and speculation becomes all the more rampant when hard facts are so thin on the ground.

[Rory166]

There do seem to be some wild figures being mentioned in this thread with regard to weight penalty. What we do know for a fact is that the 8 cells used weigh 22 Kg in total. Now multiply that by whatever factor you have for the existing approved technology subtract 22 and you have the weight penalty.

My fear in this instance is that the very fact of the approval process has in this case led to the use of a fundamentally less safe chemistry because it is already approved for aerospace use. The assumption being that the numerous fires that have occurred with LiCo batteries are down to careless use and this would not happen in aviation.

There can be no doubt that the charging arrangements include individual cell voltage monitoring and temperature monitoring seems most likely.

I think the idea mentioned in a much earlier post of isolating the battery during flight has merit as a wokaround solution. After all these batteries are only a standby and have negligible self discharge rates. So charge the batteries on the ground then switch off charging, continue to monitor cell temp and voltage during flight.

[DozyWannabe]

pressure on line pilots to treat [engineering documents] as sensitive commercial information

Are we sure that's the case here, or could it just be that the materials are a bit thin on the ground at the moment? Agree totally with your point though.

[Chris Scott]

Rory166,

The problem with banning battery charging in flight is that, for profitable long-haul operations, turnrounds are so short and infrequent, and flights so long...

[Chris Scott]

DozyW,

Am going partly on what TURIN wrote a few days ago.

However, there must be a fair number of grounded B787 crews at the moment, who are kicking their heels and presumably surfing the forums to see what is being speculated. Have you found something I've missed?

[TopBunk]

@Chris Scott

The following link has a basic overview of the electrical architecture in it. Worth noting the Boeing publication os from 2005, so it may well have changed since then!

B787 Systems and Performance (http://www.smartcockpit.com/aircraft-ressources/B787_Systems_and_Performance.html)

Hope that is of some use.

[Chris Scott]

TopBunk,

Thanks, I had that one. It does something to whet the appetite. A bit like Eiffel's sketch on the paper tablecloth...

Chris

[Rory166]

Bearing in mind these batteries are only a standby and not used in any routine situation.

The self discharge rate of these batteries is I believe 8% @ 21C and 15% per month at 40C. If we take 15% as a worst case. The maximum allowed charging rate for these cells is 1C ie. 65A, say for safety a max charging current of 30A has been selected by the designers that would require 20 mins per month of charging. Adjust the figures to the actual max charging rate.

I am confident enough time is spent hooked up to ground power to recharge these batteries.

[Chris Scott]

Rory166,

That's interesting, provided you assume that EXT power is always available on the ground. What would the crew do if none was available?

[TURIN]

Started the APU?


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[TURIN]

Started the APU?


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To be honest the beast needs so much power to run its systems you are better off on APU anyway. Less load shedding. Unless you have access to 3 GPUs of course!



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[Chris Scott]

Hi again, TURIN,

We were discussing how to avoid using the APU battery, I think, to avoid having to recharge it. (Sounds crazy, doesn't it?)

(Any schematics for us yet?) :}

[Lyman]

Chris Scott

Only part of the solution would be not charging enroute. It is off handedly suggested by the rule, since this portion suggests the requirement is for minimum (state of) charge for launch, not inflight....

(8) Any lithium ion battery installation whose function is required for safe operation of the airplane must incorporate a monitoring and warning feature that will provide an indication to the appropriate flight crewmembers whenever the state-of-charge of the batteries has fallen below levels considered acceptable for dispatch of the airplane.

So this is a checklist item for flightcrew pre launch.

Again, it seems counterintuitve that the rule would call for inflight charging (maintenance) in a standby system. It does not imply that enroute charging is not allowed, but it could be read that way. NTSB has said the voltage of the battery did not exceed its limit in the JAL accident.

It is hard to fathom that this was not considered long ago, I am sure it was. I would have lobbied for "no charging during flight", perhaps either side of wheels up by 30 minutes minimum. However, that implies charging enroute would need to be prevented, (defeated). If it was possible, some one would.

Technically, charging a standby system in flight is oxymoronic. If the batteries are on line, in an emergency, and the charger is active, the load is borne by the CHARGING SYSTEM, so why have standby batteries at all?

And begs the question I asked awhile back. If the Battery is on line, (under charge) and the draw is in any way variable, see below, @ edmundronald.:ok:

[aterpster]

Bound to happen:

http://i201.photobucket.com/albums/aa214/aterpster/787onMSFS_zpsa87b55d7.jpg

[edmundronald]

In some Lithium batteries, excessive discharge is as dangerous as overcharge. They are usually protected by discharge cutoffs.

[Chris Scott]

Lyman,

The point of a battery is to provide short-term electrical power when other sources of it are not available?

Turning to the APU again, I think we need to understand the raisons d’être (missions) of both the APU battery and the APU itself. There seems to be an assumption by some posters here that:
(a) the APU is only to be used during in-flight abnormal or emergency procedures; and
(b) it should always be possible to start it without recourse to the APU battery.

Lacking access to the FCOM, I can only speculate, but an APU – even one that does not have to supply copious amounts of bleed air - weighs a great deal more than a couple of lead-acid batteries, and occupies more space. It must justify its existence. The notion that it is not to be used in “Normal Procedures” is therefore unlikely. That would also assume that all the airports on your B787 network have rapid-deployment “ground-conditioning” units and high-rated ground power at every gate or stand at which you will ever have to park. (Preferably, the tugs would supply similar electrics, to enable engine start during push-back.) And that is to ignore your diversion airfields.

Think of an airline like Ethiopian. Does Addis Ababa have such facilities? And what about the other African cities on their network; such as Cairo, Dakar, Johannesburg, Lagos, etc., that they may be planning to send their B787s to later?

Even at the most sophisticated airports, there will be occasions when the crew arrives at the aircraft only to find no suitable ground power available. That’s what an APU is for, and the only way to get it started will be with its dedicated battery. 40 or 50 mins later, you may be getting airborne, with an ETOPS leg later in the flight. Ceasing recharging the battery before take-off could leave you with an insufficiently-charged battery, but we have no data on that.

Depending on the certificated ETOPS assumptions for the aircraft, as I wrote in an earlier post, banning in-flight charging might necessitate starting the APU in flight prior to the ETOPS leg (using generated electrics). If that was unsuccessful, however, you might have to divert. So an interim solution could be to start it before departure, and leave it running until the end of the ETOPS leg. Fortunately, an idle APU uses modest amounts of fuel at high altitude.

The banning of recharging the APU battery inflight would not be tolerable in the long term. The advantage of a dedicated APU battery, such as Boeing traditionally provides, is that it can be used to start the APU even in the event of total generation failure. Aircraft using the main battery for APU start normally cannot risk that.

[Lyman]

Hi Chris.

No, I do understand the role of the APU. Simplified: The APU must be available in an emergency, or other. The APU may need to acquire a start from the APU BATT. Fine. Let's say the APU starter circuit is not available, the APU BATTERY is used to spin up a start.

1. The APU starts, and provides power. Standby Batteries go off line.

2. Once started, the APU has two 225kva generators, capable of powering the aircraft without the need for additional power from APU BATT EMER.

3. The APU won't start in:

a. Normal flight? no problem, the Two main engines have ample power

b. Emergency? Now this is a problem, and the APU cannot supply power, it has not started. so,

c. The APU BATT can supply power to exhaustion, (What is that Requirement?)

d. The RAT deploys, providing ELEC. And HYDRAULIC.

I think my question would be: If using APU for ground power, the APU battery must be recharged in isolation, first, just as one would not attempt a start on APU with APU circuits open, the draw on its start BATTERY could be a serious problem....From the data of these two incidents, the problem seems to be around the BATTERY being on line when using the APU on the ground, and recharging the APUBATT at the same time.

So the answer in the interim may be to start the APU off the GEs before shutdown. And whilst airborne. GE starting Pratt Whitney, that's kind of....cute.....Keep the APU BATT as a STAND BY, unless in an emergency. It seems kind of, creepy, to see the APU started by a cleaning crew., using sensitive LITHION power.

As in JAL/BOS?

[sb_sfo]

In the BOS case, it is SOP to use APU power only for normal turns. There is a limitation on the APU that once it is shut down, it requires 25 minutes cooldown due to shaft bowing before it can be restarted. So, on a 90 minute turn, they start it on taxi-in to the gate, and leave it running for the entire turn. They don't even bother with GPU power unless the aircraft is going to be on the ground for a longer time.

[vaschandi]

The point of a battery is to provide short-term
electrical power when other sources of it are not available?


I would be not surprised if that is not the case for the 787!

I am sure you checked on Boeings´homepage their remarks about the
move from a hydraulic to an electrical brake system.

So may be one source of the multiple independant power distributions
to the brakes could be the battery itself.--For normal operation!

[Ancient Mariner]

Lots of talk about charging, discharging being the problem, fact is I had a Li battery, fresh from the manufacturer go bang while in storage. Not a big battery, but still. The manufacturer could not explain why.
Per

[TURIN]

Lots of questions here.
Here goes.
1. No way am I posting "EXPORT CONTROLLED-BOEING PROPRIETARY-Copyright unpublished work. IE SCHEMATICS.
Sorry but I have a mortgage and mouths to feed.
I will however enter into discussion to try to increase knowledge and understanding, especially mine.
2. Referring to my own hand written notes, the battery can be recharged on the a/c in less than 90 mins.
3. The APU can be started using power from either: APU Hot Battery Bus, AC Bus L1 or AC Bus R2. Depending on which busses are powered, which in turn will depend on what power sources you have available. EG Engine Gen, Ext Pwr (Two Fwd One Aft).
4. Brakes systems are powered from Hot Battery Bus when no normal AC Bus is available. IE. Towing without APU. In an emergency though, only three of four, brake systems are powered- from the Backup Bus, which of course, can receive power from the RAT Gen.



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[TURIN]

Lyman.
Cleaners do not operate cockpit systems. Unless they have been trained and authorised.


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[TURIN]

Lyman.
The APU Battery supplies the APU Hot Battery Bus ONLY. AFAIK it's job is to start the APU when no other power is available and power the Nav Lights when towing without APU. Thats it.


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[bsieker]

Ancient Mariner,


Lots of talk about charging, discharging being the problem, fact is I had a Li battery, fresh from the manufacturer go bang while in storage. Not a big battery, but still. The manufacturer could not explain why.


Of course that can happen if there is a defect (either from manufacturing, as in your case, or from prolonged use, e. g. through formation of dendrites), but it is much rarer than during charge/discharge, and having it happen on a relatively small fleet of aircraft twice within a few days is stretching credibility a bit too far.

So, yes, problems with charge/discharge control seems the best bet right now.

I smell software.

It is very hard to demonstrate software to have an "extremely remote" failure probability, so I read the special conditions for the Li-Ion exemption as requiring an additional (fail-safe) over-temperature and over-voltage cutoff, in case the (software-controlled) battery control system fails.


Bernd

[vaschandi]

Thank you very much Turin!

From your hand notes..., is the MAIN BATTERY for normal operation in flight
only a backup/emergency source, or is it also used as normal power distribution?
--Does it need to be charged in flight?

Braking system: Is there any hydraulic backup (accumulator), or is everything electric? --Battery= backup?

[TURIN]

From what I can see the only system that is supplied directly from the Hot Battery Bus in normal flight, is the Wireless control units for the emergency lights.
Does it need to be kept fully charged in flight?
I would say yes. If you are in such dire straights that any systems need power from your main battery, you need every amp for as long as possible.

Brakes are ALL electric. No hydraulic back up. Just multiple independent power sources.


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[glad rag]

I think you have to take a step away from the "normal" with this cab, and think what the advantages of all electric are.

My first has to be the electric compressors. Even with a double flame out surely there must exist the provision to, even partially, retain pressurisation to sustain the passengers? Well so long as you can get the apu running and both apu gen's online.....

Any thoughts?

[Rory166]

Thank you for lots of useful information.

Seems the maximum charging rate is 45 A. Fair enough.

So the battery load in normal flight is only the emergency light wireless receivers.

As we know there is a diode unit in the output of the main battery. My question is is not possible to have the hot battery bus fed from a transformer rectifier unit in normal flight thus keeping the diode reverse biased?

Without any doubt batteries need to be fully charged during flight and recharged during flight if used. The question is with a self discharge rate of less than 15% per month does routine inflight charging need to take place?

There has been speculation here about software in the charging system. As far as I know it is accepted practice to have software written by different teams for triplicate software flight control systems. Because you can never positively prove a software system is safe. Does this apply in some way to the quadruple battery charging system. Not that 4 is a suitable number for a voting system.

[Rory166]

There was reference earlier in the thread to 787 crew kicking heels. Presumably if their employer also has 777 then this need not be the case?

[bsieker]

Rory166,

[...] As far as I know it is accepted practice to have software written by different teams for triplicate software flight control systems. Because you can never positively prove a software system is safe. Does this apply in some way to the quadruple battery charging system. Not that 4 is a suitable number for a voting system.

I don't know about the 787, but this is rarely done in practice, because it doesn't really work. It is far better to have very good requirements specifications and then system specifications derived from that, and then make one very good implementation, rather than have several, which are merely "good". The resources saved from having only one team of software engineers is best put to use getting the requirements and specifications right.

Boeing tried diversity on the 777 but had to abandon it, and independent academic research also showed that diversity did not work well in practice. See this paper (http://www.coe.pku.edu.cn/tpic/20119263710178.pdf).

The most common error source is bad requirements, and since all diverse teams would be working from the same requirements, the software would contain many of the same errors. This is important, since it negates the whole point that diversely developed implementations would have different errors.

As far as I know, no airliner in wide use uses diversely developed software. All of them have had some problems, but none of them crashed because of flight control software problems, and the systems are generally extremely reliable. The only accident I know of concerns Qantas, where several severe injuries occurred when the flight control computers ordered an abrupt nose-down input resulting in a peak normal acceleraction of -0.8 G.


Bernd

[TURIN]

Glad rag.
If you lose both engine's gennies then you are relying on the APU to be started, quickly. The Cabin Air Compressors (CACs) can draw up to 105KVa each, so a battery is no use there.
There is also a Ram Air scoop that opens in the left wing/body fairing. This Alternate Vent System (AVS) cannot keep the cabin pressurised though.



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[Tu.114]

So is the APU a no-go item on the 787, or will the MEL 49.something allow a release?

[TURIN]

MEL. According to someone else who posted on one these threads.


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[cockney steve]

As an "outsider" I have so far resisted the temptation to post. However there seems to be a dire lack of understanding of fundamentals.

As an aside, the Bentley Arnage motor-car(carries 1 driver and 3/4 Pax.) has 2 batteries of~ 60 AH capacity. When parked, the "standby load" ( electronic "memories" and the like , is provided by ONE battery.

In an infrequently -used car, this gets discharged such that Central-Locking ceases to function...BUT the second battery has capacity to start the car and then all warning, self-check, courtesy-light-systems etc. come on -line POWER PROVIDED BY THE GENERATOR- which also , via a split-charge system, recharges BOTH batteries.

What's so different?- except the Plastic Fantastic sosts a few million more AND has 3 alternative power-sources as well as 2 batteries.

In both cases, system-power is generated "on demand" the batteries are purely a reservoir of energy to get a generator started. I'm astounded at the fact that a huge, power-hungry beast such as this, has such miniscule reserve-supplies, but there again, the chance of 4 main gennys + 2 APU gennys + a RAT genny (which "should" supply enough power to kick the APU into life) makes the need for big batteries superfluous.

As I've stated previously in other threads, the model helicopter world are early adopters of Li technology...these people WILL invest a couple of weeks' wages in a flying-machine which may well catch fire, have an electronics glitch or otherwise self-destruct.

THE RISK IS MINIMISED BY PROPER CELL-MANAGEMENT.
You note I did NOT say "Battery" Several other posters have pointed out - the charger MUST monitor EACH cell continuously.

Discharge is done also via an electronic circuit that eliminates out-of design- parameter excursions.

I find it difficult to understand why Boeing has not arranged their batteries and associated controllers on a modular basis...It should be feasible to" un plug" the battery/controller packs from the aircraft's main harness and substitute with an alternative Certified battery/controller pack......
Oh, Wait.... they had absolute blind faith in the unproven technology and didn't bother to make an alternative strategy, "just in case"

Regarding the "can't add weight, otherwise everything will demand a few extra pounds"-argument,- RUBBISH There isn't another on-board system with the KNOWN risk of unexplained spontaneous combustion .

These Lithium cells are the ONE issue where there are still unquantifiable risks.--Composites, you say?... plenty of light aircraft, racing-yachts and cars have come and gone and a huge database of knowledge has been aquired.

The Airframe is not the problem, nor the brakes, entertainment systems or aerodynamics....
Electricity and it's storage is the achilles heel of this aircraft and until it's sorted, the Press will have a field-day and feed sensationalist horror stories to the revenue-generating Pax.

Re-load-limitations.... Is the airframe Really load-limited by Pax+ luggage? -or are the majority of flights conducted mixed pax/freight.

Obviously, were one carrying lead-ingots, weight would be the consideration, but freighting, say, flowers, you run out of volume long before weight becomes an issue (other than balance )

Please don't all jump on me at once!

[DozyWannabe]

As far as I know, no airliner in wide use uses diversely developed software.

I'm certain the A320 does, and I'm pretty sure the other Airbus FBW models followed suit. They also had exhaustively reviewed requirements specifications. IIRC the academic paper you refer to actually said that it was impossible to verify at that stage whether multiple implementations had an appreciable benefit, but it did not say that the process had no potential benefit.

Boeing's T7 software was always going to be significantly more complex than that of the Airbus series, simply by nature of the systems design - that may be why they ran into probems and abandoned the methodology.

[Chris Scott]

Bernd and Dozy,

The flight control computers on the A320 - ELACs (2 off) and SECs (3 off) - each have a control channel and a monitor channel. IIRC, in both cases the software for the control side was written by a different team from the monitor side. (The ELACs come from a different vendor to the SECs.)

There is no voting system. If a monitor channel is in disagreement with its control channel, the relevant computer shuts down.

Bernd, you are of course right (correct!) to say that the design team has to know what it needs, and communicate its requirements to all the software teams without ambiguity. IIRC, they used either Maths or logic diagrams (AND/OR gates, etc.).

[DozyWannabe]

Cheers Chris, I was sure it was something like that.

[Lyman]

The genesis of the original discussion around discrete, or divergent (anomalous) design, originated with the initial EAD re: pitots, AF447, AFAIK.

Actually, before that, with BA038, and common (ICE/FUEL) failure that cost a Hull, and a compound fracture of a Femur.

EG: had 038 been powered by a GE on the starboard side, the accident would not have occurred.

That actually more precisely describes anomalous SPEC....

[Chris Scott]

TURIN and sb_sfo,

Thanks for all that! A number of morsels to chew over with relish. Should have remembered how paranoid the Yanks are on sharing their technology. (Unlike we Brits, who hand it all away for free!) When, in 1986, our two A310s ended up being sold to Colonel Gaddafi (RIP...), the US govt went mad about the possible leakage of info, in relation to the GE engines, IIRC.

First thoughts are it's very interesting that the APU is normally run throughout a 90-minute turnround. Just like the old days!!! In the late, increasingly "green", 1990s, many airports got very excited if we didn't shut ours down within 5 mins of arrival... Is this a particularly quiet, low-polluting APU?

Yesterday, I proposed on this thread that the APU could be left running off-load from the beginning of the flight until the end of an ETOPS leg. This might be an interim measure if charging of the APU battery in flight was considered unsafe until a new charge system is developed. From what you say now, is the APU battery already restored to a fully-charged condition by the end of a 90-minute turnround with the APU running? If so, it would solve that problem.



Chris

[bsieker]

DozyWannabe,

The way the A320's computers were developed is not the same as what we mean here by diversity. In the stricter sense this means identical functionality, fulfilling the same requirements is implemented by different teams of developers.

The paradigm for the A320 was two-fold, but both aspects are different from diversity:

- There are different types of computers that perfom different, but partially overlapping functions. These may or may not be made by different developers or even different companies. E. g. there are the ELACs performing elevator and aileron control in normal and alternate laws, and the SECs, which could also perform elevator control, but in degraded laws. So both types were not developed to the same requirements, but to different ones.

- The other idea was hardware-diversity, in that all computers have independent command and monitor channels, that perform the same functions, and according to the same requirements, but run on different hardware, in case of the ELACs Motorola 68000 for the command channel and Intel 80186 for the monitor channel, if I recall correctly. If command and monitor channel disagree, the computer considers itself failed and shuts down.

In large parts already for the A320, and more so for later models, automatic code generation was used from formal specifications. Still not sure about different teams for command and monitor channel.


See, e. g. Chapter 12 of The Avionics Handbook (http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_12.pdf).

(I just saw this crosses with Chris Scott's post ...)

Bernd

[sb_sfo]

From the 2010 study guide, the Boeing MMEL says the APU battery can be inop (or maybe removed?) if all engine VFSGs are OK and you stay within ETOPS 180.

[Chris Scott]

sb_sfo,

Thanks for the MMEL reference. 4 ED gennies does seem a safe situation to start ETOPS 180, particularly as you have the Main battery and the RAT to cater for a (temporary) double flameout.

The double engine failure, leading to a forced landing/ditching, is not part of the ETOPS remit, I guess, but the Main battery and RAT should give you enough EIS to perform it.

[Turbine D]

Hi Chris,

A little info for you on the B787 APU. It was designed and built by Hamilton-Sundstrand, now part of United Technologies. The model is the APS5000. It weighs 540 lbs. and develops 1,100 shaft horsepower. It is a variable speed APU, speed determined based on temperature and altitude. It is 50% quieter and has 10% lower emissions compared to a B767 APU. This makes it less objectionable to being run on the ground at a gate during a relatively short turn around situation. If it is shut off during flight, it is capable of being started at any altitude during flight up to 43,100 feet which is remarkable for a turbine engine, usually they don't like to start very well at high altitudes.

My understanding is that for a B787 ETOPs flight to take place, the APU and associated generators must be operable or the plane can't fly an ETOPs route.

sb-sfo pointed out:
There is a limitation on the APU that once it is shut down, it requires 25 minutes cooldown due to shaft bowing before it can be restarted.
This is surprising to me in that the usual problem with small turbines is core lock or near core lock. This is because the tolerances between the rotating parts and the outside diameter casing are tighter to prevent leakage and efficiency losses, much more important on a small engine verses a large engine. The down side is the casing cools much faster and shrinks around the internal rotating components. Since the engine is so short forward to aft, I would think the shaft would not bow.

and Lyman, Pratt & Whitney doesn't start either GE or RR engines on the B787, UTC does, P&W is a separate division entirely...

TD

[sb_sfo]

You're probably right about core lock- shaft bowing was a translation from Japanesehttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

[Lyman]

TD

and Lyman, Pratt & Whitney doesn't start either GE or RR engines on the B787, UTC does, P&W is a separate division entirely...

Don't mind me, I was reminiscing about some work I got to do on a generation plant that backed up a substantial wind farm. The energy came from a stack of JT8Ds, and I was thinking the HS APU puts out just about the same power as the much larger Turbine. My bad.....

[Machaca]

The Chicago Tribune reports (http://www.chicagotribune.com/business/sns-rt-us-boeing-dreamlinerbre90m0zo-20130123,0,4295551.story):

Japan: overcharging unlikely cause of Dreamliner woes

TOKYO/WASHINGTON (Reuters) - Japanese regulators have joined their U.S. counterparts in all but ruling out overcharged batteries as the cause of recent fires on the Boeing Co 787 Dreamliner, which has now been grounded for a week worldwide.

Solving the battery issue has become the primary focus of the investigation, but with excess voltage more or less off the table, investigators are still hunting for a possible cause.

Last weekend the U.S. National Transportation Safety Board said the fire on a Japan Airlines Co Ltd 787 in Boston was not due to excess voltage, and on Wednesday, Japanese officials all but ruled it out for the incident on an All Nippon Airways Co Ltd plane there.

"On the surface, it appears there was no overcharging," said Norihiro Goto, chairman of the Japan Transport Safety Board, at a media briefing.

[Lyman]

If the discussion was to halt now, and a spontaneous ignition solution had to derive, dendrites due age and lack of monitoring would be my posit....Maybe an MRI of each cell periodically? (I jest)...sort of

in the scheme of things, I give Boeing an A+ for the composite solution to efficiency, an A+ for its elegant electrical system, an A+ for their part in powerplant development, and an F for the ironic and more or less last resort choice of Lithium chemistry.

A two hundred million dollar ship grounded by regulated, demanded back up batteries

Probably unnecessary, so long as all served aerodromes have a start cart. Maybe Airbus can get the archaic requirement for batteries extinguished in time for the 350?

Dendrites as "Fossils"? Likewise FAA regs?

[peter we]

The final straw for LOT, apparently they are paying around $300k per month each for their 787's

PLL LOT to transfer its assets to Eurolot?

22nd January 2013

According to Rzeczpospolita, the Polish government will soon decide to transfer all assets in national airline PLL LOT to smaller state-owned airline Eurolot. “Restructuring the airline by transferring everything that is left in it to Eurolot is the only way to save the Polish carrier,” an unnamed official told Rzeczpospolita.

LOT currently doesn't have many assets to transfer. It only owns its logo and airport slots (a time window for planes to take off and land). The LOT planes are rented and its headquarters has been sold, and carrier only leases it.

According to the newspaper, the government has obtained unofficial information from the European Commission that it disapproves of public financial aid for the airline.

PLL LOT to transfer its assets to Eurolot? - Warsaw Business Journal - Online Portal - wbj.pl (http://www.wbj.pl/article-61636-pll-lot-to-transfer-its-assets-to-eurolot.html?typ=pam)

[sb_sfo]

it was rather inconsiderate for the rest of the world to rain on LOT's inaugural service to Chicago last Wednesday. As I understand it, they sent the airplane to ORD, and there it sits, grounded.

[gas path]

B787 APU does suffer from shaft bow. (The problem will be modded out sooner rather than later).
It does not require a 25 minute 'cooldown'. IIRC any limitation is for a restart after it has been shutdown
B777 APU is also capable of being started at altitude.

[RR_NDB]

bsieker (http://www.pprune.org/members/183953-bsieker):

(http://www.pprune.org/rumours-news/505455-faa-grounds-787s-17.html#post7650130)So, yes, problems with charge/discharge control seems the best bet right now.

I smell software. (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-17.html#post7650130)

It´s possible to implement an electronic discharge control. The adoption of higher voltage (32 V) allows. I don´t know if it is being used. We will learn.

The traditional batteries are quite "fault tolerant" (charger included in this comment).

It´s possible to implement this in the "analog world" but i also don´t think these approach is being used. May be should be considered to save the "wonderful but dangerous batteries" (When abused expel hot spray and even fire) :E Like a furious dragon :)

[sb_sfo]

DOT chief pledges total transparency in 787 review | ATWOnline (http://atwonline.com/aircraft-engines-components/news/dot-chief-pledges-total-transparency-787-review-0123)


Responding to media criticisms (http://www.prnewswire.com/news-releases/too-close-for-comfort-pentons-air-transport-world-questions-governments-proximity-to-boeing-before-grounding-787-fleet-187504361.html) about how DOT and FAA publicly handled the 787 issues after the Japan Airlines 787 incident, LaHood said, “We did what we did, we did the right thing … on the day we announced the planes were safe, they were.”


And then, they weren't

[lomapaseo]

Responding to media criticisms (http://www.prnewswire.com/news-releases/too-close-for-comfort-pentons-air-transport-world-questions-governments-proximity-to-boeing-before-grounding-787-fleet-187504361.html) about how DOT and FAA publicly handled the 787 issues after the Japan Airlines 787 incident, LaHood said, “We did what we did, we did the right thing … on the day we announced the planes were safe, they were.”

Makes sense

safety is a state of mind prediction of the future based on the data at hand.

Just because something has broken doesn't mean that it is now unsafe.

[RR_NDB]

toffeez (http://www.pprune.org/members/399249-toffeez):

Your # 259 (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-13.html#post7646656)

Agree!

:ok:

Mac

[RR_NDB]

WHBM (http://www.pprune.org/members/59838-whbm):

There was an old adage that the best airliner would be designed by Lockheed, built by Boeing, and with Sales & Marketing by McDonnell Douglas. (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-14.html#post7647328):ok:

One day I trust that Boeing will fully wake up to this.

:ok:

[RR_NDB]

SaturnV:

Still, safeguards for lithium-ion batteries have progressed to the point that a fire on an airplane should never have happened, said Sanjeev Mukerjee, a chemistry professor at Northeastern University and an expert on batteries.

“If a battery of that size catches fire, then a whole bunch of mechanisms didn’t work,” Mr. Mukerjee said. “Whoever is making that battery is doing a really bad job.” (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-7.html#post7640522)

I agree! (Battery system)

[RatherBeFlying]

LiFePO4 batteries seem to have been developed too late to get into the 787 design, but something tells me retrofit may be getting serious consideration;)

[jcjeant]

Hi,

EADS (Airbus) don't like more security !
EADS, Airbus' parent company, fears that the damage that ground 787 Boeing delays obtaining the certificate of airworthiness of the A350, its trump card to break into the market for long-haul.
EADS craint que les problèmes du 787 retardent l'A350 d'Airbus | La-Croix.com (http://www.la-croix.com/Actualite/Economie/Economie/EADS-craint-que-les-problemes-du-787-retardent-l-A350-d-Airbus-_NG_-2013-01-22-902238)
Google*Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.la-croix.com%2FActualite%2FEconomie%2FEconomie%2FEADS-craint-que-les-problemes-du-787-retardent-l-A350-d-Airbus-_NG_-2013-01-22-902238&act=url)
He feared they reinforce accordingly test procedures and certification of new aircraft, and therefore that of the A350.

[peter we]

Define what you mean by "risk"

I have yet to see what evidence applies in this case to the level of risk (either regulated by statue or to somebody's concept of safety).


Makes sense

safety is a state of mind prediction of the future based on the data at hand.

Just because something has broken doesn't mean that it is now unsafe.

You really believe in the 'I don't know anything about it, so it doesn't exist' approach to safety, don't you?

Fortunately the FAA (who have a clear definition of risk, BTW) is going to have to persuade the Japanese and European's - as well as Congress- with scientific method not bull****.


but something tells me retrofit may be getting serious consideration

Airbus stated it would take them 3-4 months to change the battery in the a350, its not something they would consider doing if they didn't have to.

Identifying what went wrong with the battery will probably take a long time. Even if its a manufacturing fault you will have to determine that the fault could not occur again and you can detect it. It was already supposed to be the most reliable technology available.

[cockney steve]

As RR NDB has stated, It's NOT just the voltage that's critical, but the current as well .
Maybe you thought (previous post) I was talking about "Toy" helicopters?....

Think about a 90 cm rotor-disc (six foot in old money), that can,and has caused fatal injuries, and you'll appreciate that these people are pushing Lithium batteries to their limits.
Motors get so hot,the field-magnets actually demagnetise.!!!! Battery-packs commonly give 5-15 minutes of intensive aerobatic flight, their life is limited to ~100 cycles in this very demanding application.

Battery self-destruct is an accepted risk ,simply because of the high energy-density and massive discharge-rate capability.

These batteries need[B] individual cell-monitoring on [B]both charge and discharge..they are now well-enough understood andthe monitoring technology well enough established, that thousands, if not millions of serious hobbyists are willing to put a month's wages in the air, powered by Lithium technology.

Direct connection to a bus is NOT an option...charge/discharge MUST be through appropriate monitoring -regulators.

Perhaps it's a problem with getting approval for an unorthodox connection-interface?

Total demand is irrelevant, the total capacity of ALL the battery-reserves on the 787 is only a few minutes of full demand.

I'm sure that properly monitored and conservatively rated, these batteries could become acceptably safe....effective controllers will keep them fully charged and prevent an unsafe discharge regime.

I strongly suspect the control interface (charge/discharge) is the primary culprit.
Agree with LYMAN. dendrites destroying a cell are probably caused by defective cell/battery management.

[hetfield]

Dr. Olaf Wollersheim:

»Im Moment bin ich mir nicht sicher, ob die Lithium-Kobalt-Dioxid-Technik für Flugzeuge überhaupt geeignet ist. Ich würde derzeit nicht in ein Flugzeug einsteigen, in dem solche Batterien arbeiten.«»Den Schaden zu beheben, könnte lange dauern« – elektroniknet (http://www.elektroniknet.de/power/news/energiespeicher/article/94373/0/Den_Schaden_zu_beheben_koennte_lange_dauern/)

Basicly he is saying, he is not sure if Li-Cobalt batteries are appropiate for airplanes and (up to now) he wouldn't enter an airplane with this kind of batteries.

[cldrvr]

The U.S. National Transportation Safety Board is looking at issues raised by more than one whistleblower as it investigates battery failures that have grounded the global fleet of 50 Boeing Co. 787 Dreamliners for a week.

Michael Leon, one of the whistleblowers, said he spoke with an NTSB investigator this week and gave him extensive materials about his claim that he was fired around six years ago for raising safety concerns about Securaplane Technologies Inc., an Arizona company that makes chargers for the highly flammable lithium-ion batteries at the heart of the probe.

In an interview with Reuters on Wednesday and in earlier court papers, Leon said Securaplane was rushing to ship chargers that by his assessment did not conform to specifications and could have malfunctioned.

A federal administrative judge later dismissed Leon's complaints after concluding he was fired for repeated misconduct, according to court documents. The Federal Aviation Administration (FAA) concluded that the pieces of equipment he complained about were never installed in the aircraft, as they were prototypes.

Leon appealed the federal court's ruling in 2011, but no decision has been reached.

Now the NTSB is taking a closer look at some safety concerns people have previously raised as part of a widening investigation by U.S., Japanese and French authorities into two 787 battery failures this month. One involved a fire on a parked 787 at Boston airport, the other forced a second 787 to make an emergency landing in Japan.

Kelly Nantel, NTSB director of public affairs, confirmed the NTSB was pursuing information provided by "more than one" whistleblower, but declined comment on any specific cases.

"We have been notified about whistleblowers and are pursuing that information where warranted," Nantel told Reuters, adding it was "not uncommon" for individuals to come forward with information during such investigations. The number and identity of other possible whistleblowers being interviewed in the 787 case remained unclear.


Boeing whistleblower: NTSB talking to fired Boeing worker - chicagotribune.com (http://www.chicagotribune.com/business/breaking/chi-boeing-whistleblower-in-787-case-20130124,0,4703462.story)

[lomapaseo]

Fortunately the FAA (who have a clear definition of risk, BTW)

of course they do ... but the data has not been presented in front of us for analysis and a clear understanding of the likely time frame to bring the product back into compliance.

As an investor I damn well need to have a feel for this.

As a passenger I don't give a damn since I know that neither Boring, its Operators nor the regulator will fly it in a high risk condition as defined by regulations governing Continued Airworthness

The only thing on the viewing table so far in this regard are minor issues like a battery failure to perform and a lot of hand wringing after that minor failure condition.

[DozyWannabe]

The way the A320's computers were developed is not the same as what we mean here by diversity. In the stricter sense this means identical functionality, fulfilling the same requirements is implemented by different teams of developers.

Oh, I'm sure it wasn't in the strictest sense, as such concepts were bleeding-edge back in 1982. Certain aspects were certainly used, however.

In large parts already for the A320, and more so for later models, automatic code generation was used from formal specifications.

Correct, and in line with what I was taught.

Still not sure about different teams for command and monitor channel.

Well, that's what Prof. Mellor taught us.

Anyway, back to the thread topic at hand! :)

[Machaca]

The NTSB held a press briefing today.

Here's a running synopsis compiled by Leeham News & Comment (http://leehamnews.wordpress.com/2013/01/24/live-coverage-ntsb-787-briefing/) on Deborah Hersman's (Chair of NTSB) remarks:


Expectation in aviation is never experience a fire on an aircraft. In two weeks time saw two battery events and groundings.
Significance of these events can’t be overstated.
Been working since Jan. 7 to understand what happened and why Lithium ion battery experienced thermal runaway, short circuits and a fire.
Still trying to find out why.
10:49 to 12:15 fire fighters fought the JAL blaze.
Fire confined to an area within 20 inches on the battery.
The batteries are unique to the Boeing 787.
The main battery is the final power source should all other power fail.
Minor faults found, not unusual following damage. Trying to determine the significance.
Still trying to gather data.
Boeing, FAA conducting more activities. NTSB is participating as well.
Evaluating failure modes, manufacturing records for potential issues or trends, supplier audits.
Tremendous amount of work going on around the world and around the clock.
Still trying to analyze failure modes.
[NTSB will post its PPT presentation on its website later today.]
[Going through slides right now of components of battery construction]
Independent examination in DC area for NTSB has been conducted.
Examining electrodes individually and a number of other methods looking for contaminates or defects.
We’ve done CT scan of the entire battery.
We’re looking for signs of thermal runaway (uncontrolled runaway), short circuits, manufacturing defects that could be foreign materials or material defects.
We have found some short circuits.
There is bulging present, signs of thermal runaway and short circuiting.
Still have lab testing on damaged battery and will do testing on an exemplar battery.
We’ll look at airworthiness, design components, to evaluate the safety of the systems that are integral to the battery.
FAA and Boeing are parties to investigation, Japan JTSB, GS Yuasa, Japan Airlines, France’s BEA, Thales
Naval Surface Warfare also assisting; have used lithium ion batteries for decades
JTSB in Japan is leading investigation on ANA 787 incident.
Japan ATC did see smoke around ANA aircraft.
We have to understand why there was a fire when there were so many protections built into the system.
Not yet determining the cause of the event; just sharing characteristics right now.


Q&A:


Would not answer a question if the plane would be safe to fly based on information known today. Deferred to FAA’s authority on this.
It’s very hard to tell how long investigation will take. Working hard to understand failure mode and the solution.
Grounding is unprecedented and we are very concerned. We don’t expect to see fire on an aircraft.
We are seeing symptoms right now but have to determine whether these are cause or effect. We need to understand why and how and what came first. Haven’t identified this.
We are working with JTSB to determine if there is a common cause between JAL and ANA. NTSB is a bit ahead because JAL happened a week earlier, but as yet not enough data to know if there is a common thread.
Does not answer question if Boeing thought grounding was an over-reaction, again deferring to FAA.
This JAL airplane had been in the air less than 100 hours and would not expect to see a fire.
We do not have any data to suggest the battery over-charged beyond design limit.
Still unsure if there are internal defects to the battery. This is why we are tearing down the batteries.
It is still open question if this is only the battery or if other components are involved.
We don’t know if it is possible for one cell to overcharge but the battery overall is not overcharged.
The ANA event has not been called a fire event, it’s a smoke event.
We are looking at certification standards, whether they were adhered to and whether they were appropriate. What we have seen in these two events do not comport with any design to protect against the battery events. Those systems did not work as intended. We need to understand why.
We are still evaluating all failure scenarios.
[NTSB expert]: damaged cell, short circuits could result in thermal runaway.
[NTSB chairman]: Testing exemplar batteries and how long it will take: this is interesting technology and are looking for other expertise to assist us. It can take a week to do one of the tests. This is not something we expect to be solved overnight. If we have a breakthrough, and find something that will point to a cause, we’ll get that out. But prepared to be methodical.
Our investigation will certainly look at the certification process and if we find there are vulnerability we will make recommendations. In past focused on aircraft type but could be global if safety of flight issue.
We’re looking to see if batteries were from the same batch. Looking at flight data recorders from ANA and JAL events.
We don’t know if short came first or thermal runaway came first. Have not identified sequence of events. Trying to establish why the events occurred and the sequence.

[SaturnV]

New York Times article on NTSB briefing.

http://www.nytimes.com/2013/01/25/business/the-ntsb-sees-lengthy-inquiry-into-787-dreamliner.html?hp

This particular battery was built specifically for the 787 and, according to the safety board on Thursday, used an aluminum strip coated in lithium cobalt oxide in its positive electrode. That is an older technology and is more prone to thermal runaway; it also generates oxygen as it heats, making combustion more likely.

[BARKINGMAD]

Aha! Now I know what they meant in ground skule when discussing "hot battery bus" and "switched hot battery bus".

As mentioned frequently in B737 variants' tech manuals.

I hope the NGs current Ni-Cads don't follow this trend...............

"There has been an alarming increase in the number of things I know nothing about?!" Ashleigh Brilliant quote.
:confused:

[Lyman]

I experienced one catastrophic electrical failure (marine) last year, involving a wiring problem.

The system was deactivated, rewired, and reactivated, the system had one short, and a loss of polarity. The heat, smoke and damage was breathtaking.

Lithium Ion......

The extent of the damage to a battery that is so well known suggests a major, and not entirely unknown, fault.

If Elemental Lithium plates out, and shorts a cell, there is a chaotic loss of polarity, as well as major discharge.

So the prominent suspect remains dendrites, causing dead short, polarity diffusion, heat, fire and smoke.

I think that is why such emphasis is placed on tomography, and chemical analysis of the remnants of the APUBATT by NTSB. These batteries burn, the record is clear. Boeing and FAA knew (know) this, and the Lithium requirements in the considerations are outdated.

Regulatory/certification, construction/monitoring, integration/mitigation, maintenance/service life....

Dendrites? Sound easy? I don't think so....

Hersman impresses, she has my confidence. LaHood and Huerta, not at all.

[HalloweenJack]

it would seem the FAA has the `devils alternative` in regards to the 787 - whatever choice they now make , someone will get rather upset about it... they ground it till its fixed , airlines come down on boeing , possibly cancel orders or even go bankrupt (look at LOT)

if the FAA allow it to fly and 1 catches fire in the air - lots of legal action against both boeing and the FAA , and consideration that the FAA is ` unfit for purpose`.

just some rambling thoughts that is all.

[Avionista]

Qoute from the NY Times:

“It means that the 787 is going to be grounded for an indefinite period — whether that’s two months, four months or six months, the 787 is not going to get back in the air soon,” said Scott Hamilton, managing director of the Leeham Company, an aviation consulting firm in Issaquah, Wash.

What are the financial implications for Boeing and its customers should the above prediction prove to be correct?

[old dawg]

Hello

I am new to posting anything on pprune, but I have actively read pprune forum threads for several years.

I am an engineer but not in aviation. At one stage in my career I was an EMC engineer (electromagnetic compatibility), and I spent some time actively trying to break military comms systems as well as studying their EMC behaviour.

I have no doubt that aviation EMC requirements are stringent before anything gets bolted in to an aircraft and that is right and proper.

I would however like to mention that if software and hardware upgrades are made to any system then the performance of a system may change and unintended electrical signals could be generated. EMC testing is intended to evaluate systems to make sure nothing unintended takes place that is detrimental to the correct operation of a system. If there is a problem then EMC control measures are employed which might be filters, shielding material etc. If it is a big problem then redesign might be required.

The above is a general statement but it is clear that a battery fire when an aircraft is in flight is a big problem. On the 787 the battery charging system will no doubt be studied to see if any changes have altered it's behaviour. The real issue is the extent of the 'system' boundary in EMC terms. This might be the whole aircraft or just a bit of it.

I'll be interested in the outcome of the 787 investigation.

[RR_NDB]

Hi, old dawg

787 EMI/EMC certainly were a big issue in the design. ("non metal" body and extensive use of new electric solutions)

Welcome to the Thread(s).

A lot of questions to you...

(I was at Phoenix area for a seminar in this complex subject many years ago.)

[derbyshire]

[I][I]•The main battery is the final power source should all other power fail.

No RAT?

[cwatters]

If that NY Times article is correct....

Here is a comparative study of different types of Lithium-Ion Batteries dated 2010 that mentions lithium cobalt oxide batteries...

http://www-scf.usc.edu/~rzhao/LFP_study.pdf


Lithium Cobalt Oxide Manufacturing

Current manufacturing of lithium cobalt oxide batteries is highly automated. This is because speed and quality is desired, and because some of the chemicals used are either toxic or known carcinogens. The process starts by creating a cathode paste (LiCoO2+binders). This paste is thinly spread onto both sides of a sheet of aluminum foil. Similarly, an anode paste (graphite) is created and spread onto both sides of a sheet of copper foil. Next, a separator (polymer film) is sandwiched between the anode and cathode sheets. This sheet is then wound up and placed into a cylindrical housing. Then, the cell is filled with an electrolyte (lithium salt) and the cell contacts are connected. Finally, the cell is sealed. Usually, a circuit is attached to each cell to control charging and discharging. These circuits prevent discharge past a set voltage to prevent being discharged too deeply.

snip

Though lithium cobalt batteries are equipped with safety electronic devices
along with the safety shell on its body, still they are not fully used in cars and other vehicles because of the safety concerns as they can catch fire or explode due to the extreme heat, overcharging or thermal runway.

My bold.

Another comparison of different Lithuim cell types

Types of Lithium-ion Batteries (http://batteryuniversity.com/learn/article/types_of_lithium_ion)

Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2)

The Lithium Nickel Cobalt Aluminum Oxide battery, or NCA, is less commonly used in the consumer market; however, high specific energy and power densities, as well as a long life span, get the attention of the automotive industry. Less flattering are safety and cost.

Figure 8: Snapshot of NCA

High energy and power densities, as well as good life span, make the NCA
a candidate for EV powertrains. High cost and marginal safety are negatives.

[Golf-Sierra]

One of the battery spec sheets mentioned in this thread mentioned a maximum operating temperature of 50C. That does not seem right - surely on a hot day the temperature in the EE bay is likely to exceed that.

[grebllaw123d]

The 787 battery is equipped with 8 cells of type LVP65.

Look at this link from an earlier post:
http://www.s399157097.onlinehome.us/SpecSheets/LVP10-65.pdf

[cwatters]

http://gsyuasa-lp.com/SpecSheets/LVP65-MSDS.pdf

"Do not expose to high temperatures (50C, 122F)"

Sorry if that's a repost.

[rotornut]

Pilot's take on problem: a rational view:

Video - Breaking News Videos from CNN.com (http://edition.cnn.com/video/?hpt=hp_c4#/video/business/2013/01/25/intv-boeing-787-dreamliner-mark.cnn)

[Golf-Sierra]

During any of the press conferences held so far or in any of the statements issued, has the possibility of an act of sabotage been referred to or ruled out?

Given the amount of electronics this thing has, all of it presumably controlled by field upgrade-able software, the possibility of some kind of malware being introduced cannot be ruled out.

I wonder how the aircraft systems are hardened against such threats, though I don't expect this to be information readily shared by the manufacturer or the authorities ;-)

[old dawg]

Hi RR_NDB

Thanks for the comment.

I've no doubt that the EMI/EMC design of the 787 was extensive and there will be some interesting technology in there.

I anticipate we'll all learn some more about it this year, although I also note other threads looking in depth at this particular battery design, automated manufacture, and operation.

[old dawg]

Reference posts on the battery temperatures, and a couple of questions.

It would seem that 50 deg. C is the maximun storage temperature which I interpret to be sitting in the store and not wired up.

The Operative Ambient Temperature Range is quoted as -18 deg C through to 65 deg. C

I don't know the answer to the following questions but someone might?

If the temperature in the battery system within the EE bay is towards the end of the hot end of the scale, and the charging system is active, what happens then? My understanding is that the charging system is always active but the extent of charging varies.


What are the factors that govern the charging system?
i.e. Are there particular times when there has been a heavy electrical load on the battery and subsequently the charging system is operating at a peak rate. Do any of these time periods coincide with reported battery incidents?

[a1anx]

There is quite a long piece on this in The Register (http://www.theregister.co.uk/2013/01/25/boeing_787_ntsb_report/). Apologies if this has been posted previously.

[lomapaseo]

A lesson was learned decades ago at the time of the grounding of the DC10 following the AA accident at Ohare.

Never ground unless you know the criteria necessary for ungrounding.

This is still a blank to most people at this time

I would bet that 99% of people who read these pages and all the publications linked herein believe that fixing the battery will take care of it.

The problem is that all you can fix is what you know is wrong. That still leaves any aircraft exposed to a yet to be learned unknown cause occuring some day to another battery resulting in similar circumstances. In all this the FAA must have accepted assurances of mitigation should the battery fail. Nowhere have I seen the NTSB findings of these facts against the certification standards set forth in the Special Condition.

Now we even have congress in the act of reviewing something ? Just what standards are they reviewing against?

If there would be some simple finding of a standard that wasn't met then the timimg to fix it and revoke the grounding would be known. If it is a new realization that the standards are not good enough then this problem grows immensely beyond just a single aircraft model currently being grounded.

[Cool Guys]

Good point lomapaseo. A few pages back we heard some politician spouting off that he will have to be 1000% sure the 787 is safe before it goes back into service. It seems this has become a vague criteria for ungrounding. Everyone knows 1000% safe is imposible, however 100% safe is also not posible. Unfotunatly nothing is 100% safe. We can probably get to a point where it can be 99.999% safe but with all the hysteria I dont think any politician or FAA official will be brave enough to make that call. Some poor engineer low down in the chain will probably have to make that decision. Just like pilots become the scape goats for any SW assisted flying errors, engineers become the scape goats for any political/media assisted hardware issues .
From what I have read here about Li batteries there seems to be only 2 ways that would come close to meeting the ungrounding critera:
1. Fit a Ni Cad battery.
2. Provide a battery casing which will contain any fire that may happen to occur if the tripple redundant battery managment system fails.

[ozaub]

Agree with cool guys option 2. Paraphrasing the special conditions listed at #111; the batteries shall not burn except perhaps once or twice in life of aircraft type. If batteries do burn fire must be safely contained and any emission vented overboard. So far the plane has failed on both counts

[lomapaseo]

If batteries do burn fire must be safely contained and any emission vented overboard. So far the plane has failed on both counts

I'm not so sure that I agree yet with your pass-faill assessments. I'm awaiting the NTSB facts on this.

Just take black boxes for instance. They may look burned all to hell on the ouside but the inside is still readable. The batteries are a mirror image of this. It's the harm they cause that is the measure.

As for venting overboard, that is for under-flight-conditions. It sure seemed to vent, but how much vs how much was it certified for?

[Lyman]

AD Requirements
This AD requires modification of the battery system, or other actions, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA.

............unquote FAA

1. If the authority knew exactly what was wrong, the issue never would have come up.

2. Likewise, the grounding would not have happened, so,

3. It is not possible to delineate the method of ungrounding (specifIically), prior to grounding

It is vague, not because of some systemic flaw in the wording of the AD, but because there is insufficient data to plot a solution. The onus is on the airframer, not the FAA, nor the manager of ACO.

Boeing is not entirely wrong in claiming the grounding was not necessary, from the standpoint that the special regs. were "met". They were completely in the weeds when their people officially petitioned the FAA to "tell us what we need to do....." the AD explained that in its text.......

ANA could have continued its flight, and the system may have met the parameters, or there may have been a catastrophic blaze in the forward EE Bay, and the a/c might have been lost.

I think the FAA got it right.....

[fdr]

some politician spouting off that he will have to be 1000% sure the 787 is safe before it goes back into service. It seems this has become a vague criteria for ungrounding. Everyone knows 1000% safe is imposible, however 100% safe is also not posible. Unfotunatly nothing is 100% safe. We can probably get to a point where it can be 99.999% safe but with all the hysteria I dont think any politician or FAA official will be brave enough to make that call. CG

The standard is pretty much set by 25.1309, not sure what the fuss is over by the politician's, maybe they need to learn to read n' rite while they stuff pork into their constituents, and the columnists may benefit from doing some research instead of parroting opinions from a website, and then squealing like the aforementioned piglet. That standard has it's basis in MIL STD-882 (now rev D) FWIW.

[lomapaseo]

The standard is pretty much set by 25.1309, not sure what the fuss is over by the politician's, maybe they need to learn to read n' rite while they stuff pork into their constituents, and the columnists may benefit from doing some research instead of parroting opinions from a website, and then squealing like the aforementioned piglet. That standard has it's basis in MIL STD-882 (now rev D) FWIW.

Just a casual read of airplane accident statistics would confirm that this standard is not met by many factors of ten across world wide fleets. This standard only applies to those issues not specifically covered in other parts of the regulations. In this case a Special Condition

[Cool Guys]

The NTSB breifing mentioned a page back stated: "Fire confined to an area within 20 inches on the battery." This infers that the fire was not contained within the battery casing.
Live coverage NTSB 787 briefing « Leeham News and Comment (http://leehamnews.wordpress.com/2013/01/24/live-coverage-ntsb-787-briefing/)

[Mark in CA]

Did Boeing choose GS Yuasa to supply the batteries to ensure plane sales to Japanese carriers? This report in today's NY Times seems to suggest thats exactly what happened.

http://www.nytimes.com/2013/01/26/business/selection-of-the-boeing-787s-battery-maker-raises-questions.html?ref=todayspaper

A former Boeing executive confirmed this when we spoke this week. After asking not to be named because of the diplomatic fragility of the topic, he said: “Let me put it this way: we knew the Japanese market would be Boeing’s in return for our selecting these Japanese partners. It was a silent understanding, and there was nothing in writing.” He added that Boeing’s Japanese suppliers had received low-interest loans from the Japanese government repayable only out of future profits.

[pax2908]

Fully contained also would mean that the steel box will never get hot enough to ignite some materials in close proximity. Not so easy... Was the EE bay designed with the idea that the battery box might get very hot? Any specification?

[Heathrow Harry]

I think the fact that GS Yuasa also provide batteries to things such as the International Space Station as well as 90% of US built sports vehicles would suggest that they are a major supplier across the board of high tech batteries

Boeing trying to blame Japanese airlines for THEIR decision to use them seems a little to much

[hetfield]

@Mark

thx for the link!
Very interesting...

“The greatest enemy of good aircraft is people who interfere with the freedom to shop for the highest quality,”

[cwatters]

Interesting comments here on use of different chemistry batteries in electric bikes. Comments pre date recent events.

lithium cobalt battery v lifepo4 (http://www.pedelecs.co.uk/forum/electric-bicycles/8052-lithium-cobalt-battery-v-lifepo4.html)

Lithium batteries with cobalt cathodes were abandoned for e-bikes after numerous fires caused by their intrinsically dangerous properties. Batteries with manganese cathodes replaced them.

and

Lithium Cobalt have a higher power density, can defo get more Wh/kg than LiFePo4, the difference is the Li-Co is the most dangerous type which had a bad past full of explosions. LiFePO4 is on the other hand the safest one but weight more and can get less Wh/kg. LiFePo4 are most suitable for heavier vehicles (cars, mopeds) where weight isn't such an issue.

[hetfield]

Albeit it's not possible in the moment anyway, a 2nd battery expert besides Dr. Olaf Wollersheim (Germany) wouldn't fly with 787...

Meanwhile, batteries expert George Blomgren, who worked for Eveready for 40 years told CBS news (http://www.cbsnews.com/8301-18563_162-57565753/battery-expert-i-would-not-fly-in-a-dreamliner/) that from what he knows about the incidents on board the Boeing 787s he would 'not fly in a Dreamliner tomorrow.'
'I just wouldn't feel that it was appropriate or safe,' he said


Boeing 787 Dreamliner's burnt out battery 'spewed out molten electrolytes', reveal investigators | Mail Online (http://www.dailymail.co.uk/news/article-2268152/Boeing-787-Dreamliners-burnt-battery-spewed-molten-electrolytes-reveal-investigators.html?ito=feeds-newsxml)

[TURIN]

As I have said previously. My information (directly from Boeing) is that the batteries are Lithium-MANGANESE. Where has all this talk about Cobalt come from? Or did I miss something? Posted from Pprune.org App for Android

[hetfield]

The Boeing 787 Dreamliner (http://en.wikipedia.org/wiki/Boeing_787_Dreamliner) uses two lithium cobalt oxide batteries manufactured by GS Yuasa (http://en.wikipedia.org/wiki/GS_Yuasa).[12] (http://en.wikipedia.org/wiki/Lithium_cobalt_oxide#cite_note-12)Lithium cobalt oxide - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Lithium_cobalt_oxide)

American Manganese Inc.: Boeing 787 Dreamliner Lithium Ion Batteries Based on Cobalt Not Manganese

American Manganese Inc.: Boeing 787 Dreamliner Lithium Ion Batteries Based on Cobalt Not Manganese (http://www.marketwire.com/press-release/american-manganese-inc-boeing-787-dreamliner-lithium-ion-batteries-based-on-cobalt-not-tsx-venture-amy-1748371.htm)

GS Yuasa’s lithium ion cells were chosen for the Electrical Power Conversion System in Boeing’s next generation commercial airliner, the 787 Dreamliner. This contract is a historic first as it marks the first commercial aviation application of Li-ion technology anywhere in the world. Partnering with Thales Alenia for the battery system electronics and integration, GS Yuasa’s lithium ion cells will play a key role in on-board power, providing both Auxiliary Power Unit start and emergency power back-up capabilities......Aviation | GSYuasa Lithium Power (http://www.gsyuasa-lp.com/aviation-lithium-batteries)
http://www.s399157097.onlinehome.us/SpecSheets/LVP10-65.pdf

In the last document it's clearly said..., cobalt.

[Romulus]

Did Boeing choose GS Yuasa to supply the batteries to ensure plane sales to Japanese carriers? This report in today's NY Times seems to suggest thats exactly what happened.

http://www.nytimes.com/2013/01/26/bu...ef=todayspaper


A former Boeing executive confirmed this when we spoke this week. After asking not to be named because of the diplomatic fragility of the topic, he said: “Let me put it this way: we knew the Japanese market would be Boeing’s in return for our selecting these Japanese partners. It was a silent understanding, and there was nothing in writing.” He added that Boeing’s Japanese suppliers had received low-interest loans from the Japanese government repayable only out of future profits.

If true that will now cause massive WTO ructions. As is often the case statements which sound sensible when made regarding one situation have a massive impact on another.

[HalloweenJack]

@lomapaseo (http://www.pprune.org/members/48942-lomapaseo)

The FAA grounded the aircraft because of the 2 incidence of battery fires within a shot time , the headline of ` 787 falls from the sky on fire` wouldn't sit well with them now would it.....

[Lyman]

Whatever will come of it, the FAA are looking closely to their process regarding the use of Lithium batteries.

In my opinion, we are looking at what amounts to a "waiver". Going against prior restrictions, the considerations seem rather "special case". While granting their use, the authority seem to be asking merely for a "be careful" in return.

Generally, in contravening traditional safeguards, the applicant is required to demonstrate an excess of proof, test, and mitigation.... In this situation, it seems the favorable view from FAA is careless, hence their open ended command to Boeing: "Prove the safety of this equipment...."

That may prove to be impossible, especially so when considering that the horses have bolted the corral.

Right wrong or indifferent, it will be tempting for FAA to prohibit Lithium. That may let Boeing off the hook with Yuasa, and cause Boeing to do what is clearly an expedient, but a political one, return to and refit with proven technology...

[1stspotter]

Seattle Times has an interesting story about the battery in the 787.
787 battery blew up in ’06 lab test, burned down building | Business & Technology | The Seattle Times (http://seattletimes.com/html/businesstechnology/2020199686_787batterysafetyxml.html)


In 2006, a devastating lab fire in Arizona showed just how volatile Boeing’s 787 Dreamliner lithium-ion battery can be if its energy is not adequately contained.

A single battery connected to prototype equipment exploded, and despite a massive fire-department response the whole building burned down.

[Avionista]

As I have said previously. My information (directly from Boeing) is that the batteries are Lithium-MANGANESE. Where has all this talk about Cobalt come from? Or did I miss something?

According to GS Yuasa's own website, their aircraft battery cells use Lithium Cobalt oxide:

http://www.s399157097.onlinehome.us/SpecSheets/LVP10-65.pdf

Perhaps, Boeing would not be in its present trouble if it had used SAFT Lithium Manganese oxide cells, which is what AB has done.

[hetfield]

@avionista

Look.... #415

[poorjohn]

The FAA grounded the aircraft because of the 2 incidence of battery fires within a shot time , the headline of ` 787 falls from the sky on fire` wouldn't sit well with them now would it.....What happens to a composite hull (787-style) when locally heated to an appropriately high temperature by e.g. molten metal? A self-limiting hole, uncontrolled conflagration, something in between?

[TURIN]

Well, I am confused.
The info I have is dated January 2012, Boeing official training material. It clearly states Lithium-Manganese. Odd.


Posted from Pprune.org App for Android

[hetfield]

@Turin


That's very interesting, indeed...

Another change in the fast (haste makes waste) development of the nightmareliner?

[archae86]

Well, I am confused.
The info I have is dated January 2012, Boeing official training material. It clearly states Lithium-Manganese. Odd.
NTSB chair Deborah Hersman gave a briefing on the 787 battery matter yesterday, January 25, which is posted to youtube with official-looking NTSB markings here:

Chairman Deborah A.P. Hersman briefs the media on the JAL Boeing 787 battery fire investigation. - YouTube

If you skip to time 9:06, there is a graphic on-screen depicting the electrode composition. Both the graphic and the spoken text clearly specify lithium cobalt dioxide. I'd hope they have this point correct.

[Lyman]

It was Boeing's intention to shift the batteries to Manganese for the delivered 787, evidently they changed their mind. That would be an interesting discussion.

[Taunusflyer]

NTSB with current status of investigation and lots of infos about the batteries: http://www.ntsb.gov/investigations/2013/boeing_787/JAL_B-787_1-24-13.pdf

[cwatters]

Another interesting article mentions cobalt v alternatives..

Faulty Lithium-Ion Batteries Ground Boeing's Dreamliner: Should EV Drivers Be Concerned? - Translogic (http://translogic.aolautos.com/2013/01/25/faulty-lithium-ion-batteries-ground-boeings-dreamliner-should/)

..it's worth noting that the Dreamliner's lithium-ion batteries use different cathode materials than the batteries found on most electric cars. According to Green Car Reports, the cobalt oxide (CoO2) battery chemistry found on the Dreamliner "has the highest energy content, but it is also the most susceptible to overheating that can produce 'thermal events' (which is to say, fires)." The report goes on to note that the only other electric car to use cobalt oxide battery chemistry is the Tesla Roadster, which is no longer for sale.

Boeing's battery problem can be traced back to 2005, when Dreamliner engineering stages were still ongoing. At the time, only lithium-ion cells made of cobalt oxide (CoO2) were deemed air-worthy. Since then, the FAA has approved additional cathodes, including the safer lithium iron phosphate compound (LiFePO4). LiFePO4 batteries are being used by some EV manufacturers like Chinese automaker BYD, who claim their Fe batteries offer "excellent safety performance" because of the material.

Using cobalt oxide (CoO2) as a cathode material has begun to fall out of favor, as lithium iron phosphate, nickel, manganese and other metals have been found to be safer, although cannot offer the same capacity. In all types of battery design, safety is a top priority. Lithium-ion batteries contain safety devices to prevent overheating, but if contaminants enter during production, the safety systems fail.

[cwatters]

Another change in the fast (haste makes waste) development of the nightmareliner?

Sounds more like the exact opposite. With most switching away from Cobalt were Boeing perhaps a bit too slow in doing likewise?

[hetfield]

Well, if the 787 FCOM is not identical with the reality it's haste and waste IMHO.

[Lyman]

syseng68k

Quote:
Boeing demonstrated no need for the Lithium Battery (sorry, my quote)

And, they would not have. If FAA requires a performance level that cannot be met with current technology, then they have gone into the design business. And Boeing would not design an aircraft that could not be built under current regs. Would they build a bird that was dependent on concurrent rule change? No, the rule predated the design...

If that is the case, the Dreamliner is dead. It is at least cemented in concrete to Lithium....because without back up electric, no current a/c can be airworthy. And if 787 won't certify with anything but Lithium.....

The Lithium choice has got to have been discretionary for Boeing. If mandatory, then a huge problem exists.

"Demonstrate the safety of the system....".....AD

That gives credence to Boeing asking FAA to provide a design for compliance....

"We're Stuck.....what do we do now?"

Maybe the bridge back to NickelMH burned in the EEbay?


Trouble ahead....

[Machaca]

NTSB Update on JAL Boeing 787 Battery Fire Investigation (http://www.ntsb.gov/news/2013/130127.html)

January 27

WASHINGTON - The National Transportation Safety Board today released a fourth update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston. The fire occurred after the airplane had landed and no passengers or crew were onboard.

The event airplane, JA829J was delivered to JAL on December 20, 2012. At the time of the battery fire, the aircraft had logged 169 flight hours with 22 cycles. The auxiliary power unit battery was manufactured by GS Yuasa in September 2012.

NTSB investigators have continued disassembling the internal components of the APU battery in its Materials Laboratory in Washington, and disassembly of the last of eight cells has begun. Examinations of the cell elements with a scanning-electron microscope and energy-dispersive spectroscopy are ongoing.

A cursory comparative exam has been conducted on the undamaged main battery. No obvious anomalies were found. More detailed examination will be conducted as the main battery undergoes a thorough tear down and test sequence series of non-destructive examinations.

In addition to the activities at the NTSB lab, members of the investigative team continue working in Seattle and Japan and have completed work in Arizona. Their activities are detailed below.

ARIZONA

The airworthiness group completed testing of the APU start power unit at Securaplane in Tucson and the APU controller at UTC Aerospace Systems in Phoenix. Both units operated normally with no significant findings.

SEATTLE

Two additional NTSB investigators were sent to Seattle to take part in FAA's comprehensive review. One of the investigators will focus on testing efforts associated with Boeing's root cause corrective action efforts, which FAA is helping to lead. The other will take part in the FAA's ongoing review of the battery and battery system special conditions compliance documentation.

JAPAN

The NTSB-led team completed component examination of the JAL APU battery monitoring unit at Kanto Aircraft Instrument Company, Ltd., in Fujisawa, Kanagawa, Japan. The team cleaned and examined both battery monitoring unit circuit boards, which were housed in the APU battery case. The circuit boards were damaged, which limited the information that could be obtained from tests, however the team found no significant discoveries.

Additional information on the NTSB's investigation of the Japan Airlines B-787 battery fire in Boston can be found at Accident Investigations - Boeing 787.

The NTSB will provide another factual update on Tuesday, Jan. 29, or earlier if developments warrant. To be alerted to any updates or developments, follow the NTSB on Tw!tter at www.twitter.com/ntsb.

[ozaub]

"SEATTLE

Two additional NTSB investigators were sent to Seattle to take part in FAA's comprehensive review. One of the investigators will focus on testing efforts associated with Boeing's root cause corrective action efforts, which FAA is helping to lead. The other will take part in the FAA's ongoing review of the battery and battery system special conditions compliance documentation."

Good, now we'll get honest scrutiny of the extent to which Boeing self-certificated battery installation under the relatively new "Organization Designation Authorization" procedures. If self-regulation worked, God would have given Moses 10 guidelines!

[hetfield]

(Reuters) - Japan's government stepped in to give Boeing Co's now-grounded 787 Dreamliner and its made-in-Japan (http://www.reuters.com/places/japan) technology a boost in 2008 by easing safety regulations, fast-tracking the rollout of the groundbreaking jet for Japan's biggest airlines, according to records and participants in the process.
The concessions by an advisory panel to Japan's transport ministry reflected pressure from All Nippon Airways (ANA) and Japan Airlines (JAL) and a push to support Japanese firms that supply 35 percent of the 787 from the carbon-fiber in its wings to sophisticated electrical systems and batteries used to save fuel, people involved in the deliberations told Reuters.
Exclusive: Japan eased safety standards ahead of Boeing 787 rollout | Reuters (http://www.reuters.com/article/2013/01/28/us-boeing-dreamliner-japan-idUSBRE90R05C20130128)

[rottenray]

Just to keep it balanced for those who won't read the whole story:

"We have not brought down our standards in comparison to other countries. This was a pragmatic revision," Tatsuyuki Shimazu, Chief Air Worthiness Engineer at the Civil Aviation Bureau, said....and...

QUICKER TURNAROUNDS
Changes endorsed by the aviation group, including 40 revised safety guidelines, were presented as an effort to bring Japan into line with the framework of regulations in other markets, including the United States. At least five recommendations in the advisory report benefited the 787. Four mentioned support for the Dreamliner directly.
Three of the rule changes dealt with abbreviated testing and approval of pilots who had been cleared to fly the Boeing 777 and were preparing to switch to the 787. "It (787) is highly innovative and its safety is also advanced, but it's also very similar in design to the 777," said Kinya Fujiishi, an aviation journalist who sat on the panel. "This is why we thought it would be fine to revise the rule." Bold mine.

[E_S_P]

Just throwing a thought out there...

If I am reading this correctly and the main battery IS supposed to be the last chance saloon if all other electrical power fails on-board, could the battery circuit design have been 'compromised' to allow the battery to be able to deliver 100% power in that particular scenario and be able operate outside the 'safe' operating limits ?

Or put another way, could the charging/conditioning/regulating circuits that are required to keep these batteries operating safely within their exacting operating environment, hinder the ability to allow the battery to provide the higher sustained current that is required in such a critical situation?

With a more direct (high current) connection from the batteries to the DCbuses in these emergency/failsafe situations, it now lacks the finesse needed to keep these batteries operating within safe working limits. Or due to the connection, the control circuitry isn't up to protecting the batteries from the higher running voltages that are present on the buses when the aircraft is powered up? I know someone further back has mentioned a blocking diode in one of the 787 threads – can’t remember if something similar is fitted or not :O

As Lyman mentions above, could the certification tick box requirements by playing some part ?

[Lyman]

That is the nub...

It is either a "backup Battery" or it is in use in normal flight. If in use, and recharging takes even a few minutes, it is not legal per the regulations.

It can be designed to be, but that opens up the squishy part of "BackUp".

In scuba, if you routinely dip into your back up air, you will get caught out. Likewise in fueling , if you get to using up reserves, you have no reserves.

It strikes me that utilizing a back up battery for mundane power defeats the concept, hence the "Emergency Select" switch I assume is on board.

As with the United Airlines emergency diversion to New Orleans, a loss of a generator caused a distribution problem, blank areas of the panel, etc. What was the state of charge of the two emergency batteries?

Likewise ANA. Did they Take off while charging?

Was the Battery at full charge? Both of them? Did APUBATT start the APU?

Keeping a regulated level of charge (FULL?) throughout the flight means the system is incorporating a safety system into normal flight.

I think the investigation will go in this direction. Lithium actually does look promising as a back up system, but in day to day, not so much.

Service life, maintenance and charging seem to be a weakness in

[Feathers McGraw]

Interesting little infographic here:

Lithium Battery Failures (http://www.mpoweruk.com/lithium_failures.htm)

Essentially says that an excursion in any direction outside voltage and temperature limits on a Li-ion cell will lead to problems of one sort or another, any of which could lead to a cell fire if the electrolyte ignites subsequently due to further abuse.

[Mac the Knife]

787 - batteries not included...

(Sorry, couldn't resist it)

[cwatters]

syseng68k - It's very unlikely the battery/charger doesn't have monitoring of the type you suggest. Earlier they said there was no evidence the battery had been overcharged so presumably some data is available. I'd be looking at the data in other grounded aircraft to see if there is any evidence that battery operation gets close to any limits.

[pax2908]

syseng, how do you set the thresholds to decide that (presumably) the battery needs to be put off-line and replaced ASAP? How are the data collected during normal ops. used to refine the automatic monitoring? How often are the data downloaded and analyzed by a real person?

[hetfield]

Check this (UPS 6):

http://upload.wikimedia.org/wikinews/en/a/a5/UPS_Flight_6.jpg

and this, UPS 1307

http://evworld.com/press/N748UP_DC-8_7.jpg

[Chinookflyer]

I hope this is not too much off topic - is it common to have the APU running during ground operations without somebody in the flight deck monitoring?

[flyingchanges]

Yes, common to have APU running on it's own. Almost all have auto shutdown and some even fire a bottle on their own.

[pax2908]

hetfield, not sure I understand exactly - are you saying a runaway takes place so rapidly that no monitoring can flag the problem more than ~minutes before it's going off?
I'm obviously not familiar with batteries but presumably cell imbalance (voltage or temperature or something else) can be measured, and it's slowly (or not so slowly) getting worse over time?

[fantom]

Yes, common to have APU running on it's own. Almost all have auto shutdown and some even fire a bottle on their own.


Do you mean like Airbus has had for the last twenty years?

[hetfield]

hetfield, not sure I understand exactly - are you saying a runaway takes place so rapidly that no monitoring can flag the problem more than ~minutes before it's going off?
Exactly.

The messenger (BMS) may be shot, if one cell :mad: off.
IMHO, wrong place to put in a monitoring unit.

Just have a look to upper left/right with the PCB after/before:http://avherald.com/img/ana_b788_ja804a_takamatsu_130116_1.jpg

[TURIN]

Do you mean like Airbus has had for the last twenty years?

And the B777, so lets not try and turn this into another a A v B thread shall we fantom. :zzz:


There are few here getting hung up on this battery and its purpose. It isn't much different to any other big jet.

The battery type is unusual but it does the same as most others. Boeings and Airbus.

[hetfield]

The battery type is unusual but it does the same as most others. Boeings and Airbus. Don't get it:ugh:.

It doesn't matter to be "unusual".

It matters, is it safe?

[Lyman]

My point being that if the Main and APU batteries are in casual use in flight, and the FAA has specified a "minimum Charge" to adhere to the definition of "BACKUP", then one or the other or both are constantly being charged, discharged, and for most of the time, the Battery is merely a "conductor" in line, neither powering or being reharged alone, but in constant connection.

My assumption is that the "Minimum charge" is somewhere near "Maximum Charge", so the Battery will be in line enroute. Especialy so with the MAINBAT.

Once the APU starts, can it shutdown whilst the APUBATT is below minimum charge? Since the APUBATT is charged by the vdcSG, the BATT must be restored to full charge, or may not be able to start the APU (a second time) in an emergency.

Having started the APU, perhaps draining the Battery, how can the Battery comply in flight?

This is the thing. Using a Backup Battery in its emergency configuration, not in an emergency, fails even the definition of BACKUP.......

[Dengue_Dude]

Well surprise, surprise, they're now looking at the battery charging circuit.

It was drilled into us early doors on the Tristar and DC 10 that one of the worst malfunctions was thermal runaway of batteries caused by a malfunctioning battery charger.

I don't blame Boeing for going for the easiest option, but (from this distance) I always thought that it looked just like thermal runaway - symptoms fitted perfectly. Sadly, not as cheap a fix as a different battery - unless of course the battery charger is controlled by software.

[TURIN]

Lyman.
The Main Bat is only connected to a live bus when no other electric source is available and Bat Switch 'on'. Therefore it is not discharging unless there is a power failure.
The APU Bat is charged from the F/O's Instrument Bus. This can be powered from a variety of sources, not just the APU. EG. Ext power, Eng Gen. After starting the APU, the APU Bat does nothing but sit there and get recharged. (Unless towing without APU/ENG GEN in which case it powers the Nav lights)

[hetfield]

The Main Bat is only connected to a live bus when no other electric source is available and Bat Switch 'on'. Therefore it is not discharging unless there is a power failure.
The APU Bat is charged from the F/O's Instrument Bus. This can be powered from a variety of sources, not just the APU. EG. Ext power, Eng Gen. After starting the APU, the APU Bat does nothing but sit there and get recharged. (Unless towing without APU/ENG GEN in which case it powers the Nav lights)

That's totally irrelevant!

The Main Bat as well as the APU bat f:mad: up!

[Lyman]

TURIN

Many thanks. From that, ANA Main Battery had a spontaneous failure? It must meet basic charge level to launch, so would not be charged after T/O, right?

Is the only start voltage available for APU the APUBATT? It seems unusual to require a backup battery to Start the APU in normal ops. Because if an airborne start, the APU BATT might go below legal level, and be unable to start the APU in an actual abnormal?

Not for use during Flight?

:ok:

[syseng68k]

Apologies, deleted that post because it should have been sent to tech log as
a follow up to a previous post :uhoh:

cwatters:

They must have some sort of diagnostics internal to the charger / monitoring and
data would ideally be stored locally. The fdr only has limited storage capacity,
but a subset of that data, say bus voltage and any fault codes, might be sent to
it as well. If the data from the charger / battery is lost, the limited fdr data
may be the reason why we have only been told thus far that a battery over charge
condition didn't occur. The fdr data may be the only thing they have at present.

pax2908

As for the thresholds, they would be set below cell voltage and temperature
limits. If the charger is really smart, it should also be able to predict cell
failure before it causes a problem, by comparing known good cell characteristics
against data from individual cells over time. Where data logging is used, it's
normally stored to non volatile memory within the subsystem. Often flash memory,
much like you would find in a usb memory stick, but manufactured and qualified to
a much higher specification.

[HazelNuts39]

ANA Main Battery had a spontaneous failure? It must meet basic charge level to launch, so would not be charged after T/OYou seem to be referring to item 8 of the B787-8 special conditions pertaining to lithium ion batteries:
(8) Any lithium ion battery installation whose function is required for safe operation of the airplane must incorporate a monitoring and warning feature that will provide an indication to the appropriate flight crewmembers whenever the state-of-charge of the batteries has fallen below levels considered acceptable for dispatch of the airplane. Does that exclude the possibility that the main battery would be charging after takeoff?

[Lyman]

Hi HazelNuts39,

The language is not specific, though I anticipate changes in the text.

"....must incorporate a monitoring and warning feature....etc."

The operant is "for dispatch". Since charging is not prohibited, specifically, it leaves rhe option open. BUT, any use of the battery would drop the voltage below minimum (possibly) and instantly violate the condition.

However, "for dispatch" is a threshold.

The meaning of "backup" stands alone, it must take precedence over any function that is not part of the definition. So launching, having met the threshold, implies that the voltage should be available throughout the flight, barring malfunction.

FAA regs are minimums, so I fall back on TURIN......"The Main Bat is only connected to a live bus when no other electric source is available and Bat Switch 'on'. Therefore it is not discharging unless there is a power failure."

A guess would be that ANA charged the batteries to legal, isolated (sel off), and took off. The runaway having begun prior to T/O, the charger would not be in use, but the die was cast....why would one charge after T/O? If the voltage drops below minimum, I suppose the battery could be charged, but still isolated from live bus.......that may change.

The solution is in the interface between FAA and Boeing, each working at cross purpose, but theoretically in concert. Cross purpose is not defeating, it is entirely logical, they have a different mission. FAA has to walk the tighter line, imo; they want Boeing to succeed, (promote aerospace business), while ensuring high standards of safety.

Each of them work to the edge of the mission, and the result is safe prosperous travel....

[ExSp33db1rd]

Sorry, haven't the time or energy to go through the whole of this thread, so apologies if this has been covered.

A Chemical Engineer friend of mine told me that Lithium Cobalt mix is a Fire Chiefs worst nightmare, a by product of the fire is oxygen, so there is no chance of smothering it, it just goes on to make its' own O2, and pouring water on it causes a very big bang, so they can only concentrate on cooling the surrounds until it burns itself out.

I've read a couple of posts that suggest that Boeing changed to Lithium Magnesium -so that's alright then, I'd rather be on board a 787 suffering a serious Lithium Magnesium fire than a Lithium Cobalt fire. Much more comforting on an ETOPS sector.

Interesting that these batteries are forbidden to be carried in bulk as freight on passenger aircraft - freighter crews being expendable as recently proved by UPS - but it's OK to have the equivalent of a shipload of them under the floor of a passenger 787.

I wish I was a US Lawyer, I guess there will be a lot of rich ones soon, wonder of Boeing will survive the Loss of Revenue litigation from the airlines with grounded 787's ? Or will they sue the FAA ? US taxpayer are you listening ?

Not good.

[TURIN]

Hetfield.
I am not apologising for the failures, just trying to explaine to Lyman about the system as he/she is misunderstanding lots.

Lyman. The bat switches stay selected on in flight. The breakers and contactors are controlled automatically.
The batteries will still be charging if necessary after engine start. Maintenance and flt crew check list items will determine if bat state is ok for dispatch. This is standard on all big jets. In flight the APU Bat will only be used to start the APU if NO OTHER SOURCE IS AVAILABLE.

Hope this helps.

[RR_NDB]

Note: The rationale for this post will be reviewed . The "unprecedented" is not what was imagined. Post will suffer revision, corrections or even deleted.

Hi,

TURIN:

Therefore it is not discharging unless there is a power failure. (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-23.html#post7661768)

This is unprecedented. Boeing innovated designing the first airliner using Li Ion batteries (as the main battery) AND ALSO:

Using a battery that only delivers (higher) current when there is a (very rare) failure in the DC bus.

This means:

The ANA battery (certainly older than JAL APU unit) probably NEVER* WAS USED. I.e. never delivered (high) current. Just was kept "floating" since was manufactured.

This is a radically different use of a typical battery. At least we can say this could introduce new (and unknown) possibilities. It is a truly backup unit. Not being "exercised" like (as i imagine) in practically 100% of vehicles (land, water and air, main batteries)

AFAIK the designers made the same in A380 (emergency lighting).

The failure mode of the ANA battery (or the reason for the failure) now becomes clear to me could be another completely different. Even with the same charger could be another reason. I am assuming BOS JAL 787 started the APU using the battery. And ANA 787 had no DC bus failure requiring main battery use before the incident.

The timing between both cases (intriguing) could be just a coincidence.

APU battery operates differently than main battery that just waits (charged) an emergency (in the DC bus)

I am assuming something (that will be verified) from what i learned so far on 787. (Use of Diode, APU opp. etc.) Unfortunately we don´t have yet all information (schematic diagrams, etc.) to understand completely the issue.

(*) Unless there is a discharger (between the battery and the diode unit) to cycle it (cycles of charging and discharging, during normal operation) Something not feasible for deeper discharge. (you may need it when it was recovering from the "exercise")

Note: The rationale for this post will be reviewed . The "unprecedented" is not what was imagined. Post will suffer revision, corrections or even deleted.

[RR_NDB]

Hi,

Maintenance and flt crew check list items will determine if bat state is ok for dispatch. This is standard on all big jets.
(http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7662317)

And with Li Ion there is another reason for this. It can increase it´s voltage (during charging) providing a false indication of "health" and not be able to deliver the required energy (to the bus) if an emergency situation requires it (bus voltage below, i estimate ~ 30 V). A cell that fall below a given threshold very probably will never recover. Lead Acid in this aspect can go to zero, exhibit a high internal resistance and FULLY RECOVER. I faced this situation and after charging (longer time was required) it returned to the same (anti) capability.

In flight the APU Bat will only be used to start the APU if NO OTHER SOURCE IS AVAILABLE.

Question:

JAL in BOS probably started the APU using the battery? If so the runaway probably started with hot cells (after high current use starting APU) and when receiving high current (with regime to recharge "fast")

[fergineer]

Why would they start the APU using the battery when starting with the engines running and providing power is the normal way to start an APU.Or if on the ground an Aux Power unit would be connected surely.

[RR_NDB]

fergineer:

Why would they start the APU using the battery when starting with the engines running and providing power is the normal way to start an APU.Or if on the ground an Aux Power unit would be connected surely. (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7662360)

Sure! i was concentrated thinking on main battery and was supposing APU battery as the only source. Certainly is not.

Thanks for questioning. Must go bed...:) Fatigue could explain.:\:O

This means both Li Ion (main and APU) on 787 are kept "floating" most of their life.

[Walnut]

A previous posting suggested a Lithium Cobalt mix is a Fire Chiefs worst nightmare since a fire is self sustaining as it produces its own O2. So despite the latest news that the Japanese have found no faults with their battery manufacture, should such a battery be on an a/c.?

I ask myself why have Boeing gone with this technology?

My suggestion is because the a/c is all electric then there are ultimate failure situations where high energy is needed. On every a/c I have flown before the brakes for example have a brake accumulator. The brakes on this a/c are electric, so the backup has to be the same. A high energy battery?

[tom775257]

ExSp33db1rd: The Yuasa ones involved were confirmed by NTSB as Li-ion cobalt. But yes it sounds like the BOS fire brigade didn't so much put the fire out as keep the surrounding area cool until it burnt out.

Does anyone know what Airbus plan to use on the A350? The safer, but lower performance Li-ion-manganese or the cobalt?

[hetfield]

I ask myself why have Boeing gone with this technology?

My suggestion is because the a/c is all electric then there are ultimate failure situations where high energy is needed. On every a/c I have flown before the brakes for example have a brake accumulator. The brakes on this a/c are electric, so the backup has to be the same. A high energy battery?

You are not the only one who wonders why Boeing took that risk for the benefit of a few kilogramms....

[deptrai]

You are not the only one who wonders why Boeing took that risk for the benefit of a few kilogramms....

Ambition. The 787 was a very ambitious project, on so many levels. And the sum of all the few kilograms here and there adds upp. Evolution in technology is mostly a continous, incremental process.

It's easy for us who have the benefit of 20/20 hindsight to know which kilograms might better not have been saved. Airbus has also planned to use lithium batteries on the A350, and they were not highly controversial before the recent incidents.

It's a bit ironic that a battery which is only there as a redundant contingency measure, to add to safety, now instead causes trouble, but I applaud Boeing for being ambitious- and I applaud the Japanese carriers for temporarily grounding their planes, and the FAA for issuing an AD. Every now and then there will be idiosyncratic teething problems with new technology, but no one has been physically harmed, aviation safety is better than ever, and I'm confident the issues will be resolved. Technology will continue to evolve.

[syseng68k]

deptrai:


It's a bit ironic that a battery which is only there as a redundant
contingency measure, to add to safety, now instead causes trouble, but I
applaud Boeing for being ambitiousbut I applaud Boeing for being
ambitious....
...and so do I. It's a very advanced design from the info available.
There's no progress without change and as technology and engineering solutions
become ever more complex, so will the risks multiply. There's no free lunch
and engineering will always be a devil's compromise between cost, reliability
and performance.

The A340 fbw design is still controversial in some areas, even years after
introduction, but let the record speak for itself...

[bsieker]

ExSp33db1rd,
[...] I've read a couple of posts that suggest that Boeing changed to Lithium Magnesium -so that's alright then, I'd rather be on board a 787 suffering a serious Lithium Magnesium fire than a Lithium Cobalt fire. Much more comforting on an ETOPS sector.

Just to clarify, the talk is about Lithium-Manganese (http://en.wikipedia.org/wiki/Manganese), as an alternative to -Cobalt, not Magnesium (http://en.wikipedia.org/wiki/Magnesium). Totally different stuff.

Technically both types use oxide, and not elementary metallic Cobalt or Manganese.

Yes, Magnesium can burn very hot, and continues burning under water and under CO2, but Manganese is quite different.

[harpf]

I would expet the final design to switch to LFP these are the very saftest Li chemistry. Much better weight then Pb or Nicad long cycle life. Slightly more weight than most other Li chemistry :8

[harpf]

I/m sure the battery is load tested on a regular bases, perhaps before every flight.

[Lyman]

bsieker (bernd).....


Thanks for clearing that up. It is nice to be able to share the "uninformed" yoke of criticism....

The irony is instructive, for there must be a balance among progress, risk, innovation, and SAFETY.

It is by no mistake that our Supreme Court has labelled a CORPORATION as having the attributes of an "individual".

EGO, GREED, AGGRESSION, etc. They belong in the Boardroom, not on the floor, or in the "discussions" between Airframer and Regulator.

Every bit as important as the technical, is the procedural.....

Corporations invest other people's money, to put at risk other people's lives.....

And collect the benefits therefrom. Without imbalance, there is no progress.

Without Delta, there is no velocity. Herein is a tutorial for those who wish to see it.

I am a betting man. And my money is on the FAA.

Hell hath no fury like a bureaucrat, shamed...

Relative to ops, and maintenance. This area was presented early on, and got some criticism.... The airframer has an obligation to support its product in the field. Whether Battery, or Controls system, "sink or swim" won't 'Fly'.

[robdean]

RR_NDB makes a thought-provoking point. The life-cycle and failure rate of Li batteries is very much determined by environment and pattern of usage. For instance they tend to degrade much faster if stored fully charged and/or at high temperature.

When the technology is relatively new, the application/deployment environment novel and the associated battery charge/discharge cycling pattern possibly rather unusual, it leaves open the possibility of some unrecognised factor in physics/chemistry, as there was when metal fatigue started downing early passenger jets.

[Walnut]

I believe it was the superior reserve power capacity of the Lithium battery rather than weight which led Boeing to their battery choice.
This all electric a/c is fine whilst in the air, even with say a double engine failure, as windmilling engines, RAT, an APU (if it starts) will provide sufficient electrics to power high load items like flying controls.
On the ground its a different matter.
It is interesting the A380 has a very high pressure hydraulic system 5000psi? in order to provide the necessary power for high load items.
Boeing decided electric cables were lighter? & simpler to transfer high load items. However unlike hydraulics which tend to leak in failure mode, electric cables if overloaded tend to catch fire.

[RR_NDB]

Hi,

deptrai @ (#469) (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7662827)

Perfect. I fully agree!

[RR_NDB]

Hi,

Harpf @ (#473) (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7663051)

How? Automatically? Who manages?

I hope the batteries (required to be able to deliver power when necessary) that must be kept charged sometimes are tested to show it´s "readiness".

But, this is a TESTABILITY ISSUE (frequent when you must have REDUNDANT items kept "offline")

[RR_NDB]

Hi

Robdean @ (#475) (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7663168)

Paradox:

You put "redundant for contingency" * items, keep both "ready" at full capacity, OFFLINE, and they fail twice in few days.

Murphy law put this to Boeing and US in a critical moment.

Concerning.

(*) As mentioned by deptrai @ # 469 (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7662827)

[cwatters]

A partial recap for late commers...

When they designed the 787 I think Lithuim Cobalt was the most proven of the Lithium cell technologies available.

Since then some/many other users have switched to Lithium Manganese for because of possible concerns over the safety of Lithium Cobalt.

It's possible Boeing were/are considered changing to Lithium Manganese but don't appear to have done so yet.

[Ex Cargo Clown]

If Boeing switch to Li-Mn batteries will they have to recertify the A/C?

[Lyman]

cwatters


Lyman: (post #426)
It was Boeing's intention to shift the batteries to Manganese for the delivered 787, evidently they changed their mind. That would be an interesting discussion.

As I recall, the first Limn was to be in the ANA that had the problem....

[Speed of Sound]

Does anyone know what Airbus plan to use on the A350? The safer, but lower performance Li-ion-manganese or the cobalt?

I'm not a betting man but if I were, my money would be on Li-Mn! :ok:

[ExSp33db1rd]

Just to clarify, the talk is about Lithium-Manganese, as an alternative to -Cobalt, not Magnesium. Totally different stuff.

Thank you.

[Taunusflyer]

For all of the battery affraied ones here: Currently there is no hint that the battery itself failed. The investigations are more concentrated to find the malfunction within the surrounding electrical system. We should stop the discussion which bat ist more dangerous than others. :ugh:

[Pinkman]

We should stop the discussion which bat ist more dangerous than others

Why? are both battery chemistries equally fault-tolerant and do they have identical thermal runaway characteristics in the event of a fault in the surrounding electrical system?

[RR_NDB]

Hi,

Walnut:

Boeing decided electric cables were lighter? & simpler to transfer high load items. However unlike hydraulics which tend to leak in failure mode, electric cables if overloaded tend to catch fire. (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-24.html#post7663238)

One of the most studied, discussed, quantified, checked is the Design Philosophy and the concepts adopted. Boeing decision for the change to this innovative design involved even the engines (bleed issue) and the mentioned 1.45 MW shows the "magnitude of the electrification".

Would be fascinating to discuss in a Thread the comparison of hydraulics/pneumatic vs electric. I´m mulling the idea. After the crisis recedes. :)

[Rory166]

I took the poll but got no results. Is that because I was not logged in? Can you copy the results here.

[sb_sfo]

Results:
Bad luck <5%
Poor FAA/regulatory oversight <5%
Poor QC 6%
Substandard materials 6%
Poor design 6%
Too many innovations at one time 15%
Outsourced design and manufacture 24%
Insufficeint testing for worst-case scenarios 35%

For what its worth...

[syseng68k]

RR_NDB


Would be fascinating to discuss in a Thread the comparison of
hydraulics/pneumatic vs electric
Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two. Hydraulics need heavy pumps, valves and lines to withstand the
high pressure and conversion efficiences are low.. Compressed
air needs a lot of ducting to get it to the right place. Wire does it
at a fraction of the cost and weight.

Moderen a/c need loads of electrical power and have large generating
systems anyway, so why not make as much of the system as possible
electrically powered to maximise efficiency ?. Sounds like a very
smart idea to me...

[RR_NDB]

syseng68k:

Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two.

Let´s look to an example:

Taxiing using electric motors instead of noisy turbines. (http://www.pprune.org/rumours-news/506512-i-suppose-airbus-going-ahead-electric-taxi-idea.html)

:)

Will need to go to a subroutine in next days in order to think about this comparison: Electrics, hydraulics or pneumatics.

But it seems electric "will be the future". (some exceptions, obviously)

And after this :sad: and painful teething of 787 i FIRED a big Li Ion pack (18650) in my electric bike and yet installed a micro APU :)

My only problem is: 787 battery issue ended my love with this wonderful battery. She created a trauma for me. :{ Now i am reviewing to the least possible use of batteries in my projects. Maximum cell size? 18650. thermal runaway? Make it impossible: SEPARATED cells. Worst case scenario? (a virtually impossible one): Inerting gas and a manifold to exterior from each cell. Charger? PARALLEL!!! etc. etc. etc. :mad::mad::mad:

[Ex Cargo Clown]

"Inerting gas and a manifold to exterior from each cell. " Inert with what exactly? on an ETOPS flight it will just reignite. If you keep on flooding it with halon, then you'd kill everyone onboard.

Going to have a pop at Li-Mn batteries tomorrow in the lab, far better conditions than a pumpkin lol

[RR_NDB]

Ex Cargo Clown:

Inert with what exactly?

To be studied. If not existent the manifold will be more elaborated. :)

on an ETOPS flight it will just reignite.

Each cell could die (smaller ones and with any behavior) and the remaining cells does the task (An stack is voltage redundant. Remember the parallel charger.)

If you keep on flooding it with halon, then you'd kill everyone onboard.

Fire will not be allowed to happen. Will be forced out. Like an afterburner. Batteries will not be near electronics. May be the cells distributed. :8

Ok, let´s go back to the proven Ni Cd´s. :) LOL I concede. Big problem!

Teething or GROSS ERROR? :{

[westerndh]

Tesla / SpaceX CEO Elon Musk tweeted a few days ago he's approached 787 Chief Engineer to offer help, just saw this article:

Elon Musk: Boeing 787 battery fundamentally unsafe (http://www.flightglobal.com/news/articles/elon-musk-boeing-787-battery-fundamentally-unsafe-381627/)

[vaschandi]

...may be there is no other choice...


Now Elon Musk Is Helping Boeing Save The 787 Dreamliner - Business Insider (http://www.businessinsider.com/now-elon-musk-is-helping-boeing-save-the-787-dreamliner-2013-1)

[TURIN]

1.45 MW is the TOTAL generating capacity of the engines & APU. It is not what the a/c needs. EG. Dispatch with one VFSG inoperable is allowed under MEL. Limit is 180 mins ETOPS.

The 787 still has lots of hydraulics by the way. Electrical actuators have replaced the brakes, 4 spoilers and (I think) stab trim. The rest is still hydraulic.
It is pneumatics that are the big change. No ATA CH 36 in the AMM on this beast.


Posted from Pprune.org App for Android

[Chuck Noris]

Since the grounding of the 787 and many other incident (DXB UPS) involving lithium battery. I would like to know if your airline have banned those on a passenger flight? Should they?

[hetfield]

Let's get started: Electrics, hydraulics or pneumatics, are
all means to transfer energy from one place to another. Electrics
are far more efficient and have less weight than either of the other
two. Hydraulics need heavy pumps, valves and lines to withstand the
high pressure and conversion efficiences are low.. Compressed
air needs a lot of ducting to get it to the right place. Wire does it
at a fraction of the cost and weight.

I fully agree.

The two batteries of the 787 have NOTHING to do with that, they are common for all airliners.

- APU start
- Elec Essential backup

[plasticmerc]

Inerting the battery could be done much like the inerting of the center fuel tanks!
Nitrogen generation system seal the battery bay/ isolate the battery and plumb in a feeder line to it with a nitrogen system.
But having read previous posts I don't think that would be very successful as when the battery goes off with a bang it produces Oxygen. Would the nitrogen rich area be enough to dilute the O2 content???

This is an interesting situation many airlines world wide have pinned their hopes and dreams on the 787, new routes, fuel saving replacements.
Just goes to show as the world gets more densely populated and a/c get bigger we realize how much we need a particular aircraft.
Turbo props have grown from the original 19-30- 50 now 70 seaters. now we see 90 seaters on the horizon, unfortunately regional airports and towns/cities can't fill the increase and then you end up having no regional services to such places.
Boeing have tried to do a shorter range 787 but that has been a flop, many airlines rely on 767 a/c not too big not to small good range good operating conditions. but it is old and there is nothing that would have replaced it until now.
I understand I have drifted off topic a bit but in my opinion it is all relevant.
This battery/ electrical defect will have huge ramifications to the whole aviation environment.

[The Dominican]

Latest report from the NTSB (came out on CNN) is that they couldn't find any problems with the battery maker nor its method of construction, the investigation is now focused on the charger.
Aviation authorities find no big problems at Dreamliner's battery maker - CNN.com (http://edition.cnn.com/2013/01/29/travel/boeing-dreamliner/index.html?hpt=hp_bn1)

[Arjaysee]

Hi Dominican. Looks like the focus is on the monitoring systems now rather than the chargers. The most recent NTSB release I saw indicated that the chargers passed all tests and "no significant anomalies were found".

[deptrai]

[snip...thread merge took this post out of context]

[robdean]

Just because the battery and charger 'check out ok' in investigative tests is no guarantee that redesign will not be mandatory.
Irrespective of the initial cause of malfunction (which may be upstream of the battery/charger or may be due to some overlooked variable) the outcome was a non-extinguishable burning battery. Which implies at least that this system is significantly intolerant to external contingencies.
A corollary is hydrogen in airships: it is lighter and cheaper than helium, but has distinct chemical properties which can on occasion prove disadvantageous...

[fdr]

If Boeing switch to Li-Mn batteries will they have to recertify the A/C? ECC

25.1351
25.1353
25.1355
25.1362
25.1363

§ 25.1351 General.
(a) Electrical system capacity. The required generating capacity, and number and kinds of power sources must—

(1) Be determined by an electrical load analysis; and

(2) Meet the requirements of § 25.1309.

(b) Generating system. The generating system includes electrical power sources, main power busses, transmission cables, and associated control, regulation, and protective devices. It must be designed so that—

(1) Power sources function properly when independent and when connected in combination;

(2) No failure or malfunction of any power source can create a hazard or impair the ability of remaining sources to supply essential loads;

(3) The system voltage and frequency (as applicable) at the terminals of all essential load equipment can be maintained within the limits for which the equipment is designed, during any probable operating condition; and

(4) System transients due to switching, fault clearing, or other causes do not make essential loads inoperative, and do not cause a smoke or fire hazard.

(5) There are means accessible, in flight, to appropriate crewmembers for the individual and collective disconnection of the electrical power sources from the system.

(6) There are means to indicate to appropriate crewmembers the generating system quantities essential for the safe operation of the system, such as the voltage and current supplied by each generator.

(c) External power. If provisions are made for connecting external power to the airplane, and that external power can be electrically connected to equipment other than that used for engine starting, means must be provided to ensure that no external power supply having a reverse polarity, or a reverse phase sequence, can supply power to the airplane's electrical system.

(d) Operation without normal electrical power. It must be shown by analysis, tests, or both, that the airplane can be operated safely in VFR conditions, for a period of not less than five minutes, with the normal electrical power (electrical power sources excluding the battery) inoperative, with critical type fuel (from the standpoint of flameout and restart capability), and with the airplane initially at the maximum certificated altitude. Parts of the electrical system may remain on if—

(1) A single malfunction, including a wire bundle or junction box fire, cannot result in loss of both the part turned off and the part turned on; and

(2) The parts turned on are electrically and mechanically isolated from the parts turned off.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-41, 42 FR 36970, July 18, 1977; Amdt. 25-72, 55 FR 29785, July 20, 1990]

§ 25.1353 Electrical equipment and installations.
(a) Electrical equipment and controls must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other electrical unit or system essential to safe operation. Any electrical interference likely to be present in the airplane must not result in hazardous effects on the airplane or its systems.

(b) Storage batteries must be designed and installed as follows:

(1) Safe cell temperatures and pressures must be maintained during any probable charging or discharging condition. No uncontrolled increase in cell temperature may result when the battery is recharged (after previous complete discharge)—

(i) At maximum regulated voltage or power;

(ii) During a flight of maximum duration; and

(iii) Under the most adverse cooling condition likely to occur in service.

(2) Compliance with paragraph (b)(1) of this section must be shown by test unless experience with similar batteries and installations has shown that maintaining safe cell temperatures and pressures presents no problem.

(3) No explosive or toxic gases emitted by any battery in normal operation, or as the result of any probable malfunction in the charging system or battery installation, may accumulate in hazardous quantities within the airplane.

(4) No corrosive fluids or gases that may escape from the battery may damage surrounding airplane structures or adjacent essential equipment.

(5) Each nickel cadmium battery installation must have provisions to prevent any hazardous effect on structure or essential systems that may be caused by the maximum amount of heat the battery can generate during a short circuit of the battery or of individual cells.

(6) Nickel cadmium battery installations must have—

(i) A system to control the charging rate of the battery automatically so as to prevent battery overheating;

(ii) A battery temperature sensing and over-temperature warning system with a means for disconnecting the battery from its charging source in the event of an over-temperature condition; or

(iii) A battery failure sensing and warning system with a means for disconnecting the battery from its charging source in the event of battery failure.

(c) Electrical bonding must provide an adequate electrical return path under both normal and fault conditions, on airplanes having grounded electrical systems.

[Amdt. 25-123, 72 FR 63405, Nov. 8, 2007]

§ 25.1355 Distribution system.
(a) The distribution system includes the distribution busses, their associated feeders, and each control and protective device.

(b) [Reserved]

(c) If two independent sources of electrical power for particular equipment or systems are required by this chapter, in the event of the failure of one power source for such equipment or system, another power source (including its separate feeder) must be automatically provided or be manually selectable to maintain equipment or system operation.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 35 FR 5679, Apr. 8, 1970; Amdt. 25-38, 41 FR 55468, Dec. 20, 1976]


§ 25.1362 Electrical supplies for emergency conditions.
A suitable electrical supply must be provided to those services required for emergency procedures after an emergency landing or ditching. The circuits for these services must be designed, protected, and installed so that the risk of the services being rendered ineffective under these emergency conditions is minimized.

[Amdt. 25-123, 72 FR 63406, Nov. 8, 2007]

§ 25.1363 Electrical system tests.
(a) When laboratory tests of the electrical system are conducted—

(1) The tests must be performed on a mock-up using the same generating equipment used in the airplane;

(2) The equipment must simulate the electrical characteristics of the distribution wiring and connected loads to the extent necessary for valid test results; and

(3) Laboratory generator drives must simulate the actual prime movers on the airplane with respect to their reaction to generator loading, including loading due to faults.

(b) For each flight condition that cannot be simulated adequately in the laboratory or by ground tests on the airplane, flight tests must be made.


How big a deal? Probably not too bad, it is a package but then there is a few DER's there in Boeing looking at improving their resume a bit, a fair incentive to keep it going. Pretty sure that the FAA ACO will put all the rest of us doing certification programs on the back burner, I for one won't object to that, the B787 program is a key program.

[Chuck Noris]

I fully understand that it is impossible to totally band them, but since I personally witness my own laptop auto combustion and that it is almost impossible to extinguish. I think that tolerating those should be enough. We don't need to have more on the NOTOC of a passenger flight.

If the legislation approved it doesn't make it safe.

This extract is taken from IATA website regarding some change in the regulation.

(The ICAO DGP does not consider however that these changes will necessarily reduce incidents involving lithium batteries. To significantly improve safety, IATA advocates for enhanced outreach of regulations applicable to the transport and testing of lithium batteries by manufacturers as well as shippers.)

[deptrai]

"ANA said it replaced 10 of the batteries in the months before [the recent incidents].

In five of the 10 replacements the main battery had showed an unexpectedly low charge. An unexpected drop in a 787’s main battery also occurred on the flight that had to make an emergency landing in Japan on Jan. 16.

In three instances, the main battery failed to operate normally and had to be replaced along with the charger. In other cases, one battery showed an error reading and another, used to start the auxiliary power unit, failed. All the events occurred from May to December of last year.

According to investigators in Japan, the battery on the jet that made the emergency landing showed a stable reading of 31 volts, near its full charge capacity, until 15 minutes into the flight when pilots detected a strange smell. About that time, sensors detected a sudden unstable discharge of the battery to near zero for reasons that Japanese investigators still cannot explain."

http://www.nytimes.com/2013/01/30/business/boeing-aware-of-battery-ills-before-the-fires.html?pagewanted=all