Discussion:
Boeing 787 : Are the glitches normal ?
(too old to reply)
JF Mezei
2013-01-15 08:29:09 UTC
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There have been many reports of glitches on the 787 of late.

yahoo has a list:
> http://ca.news.yahoo.com/factbox-recent-safety-incidents-boeings-787-134642591--sector.html;_ylt=AuCfvRHYcLtMdxsFouRKU_I6ssB_;_ylu=X3oDMTUxaWprZWQ2BGNjb2RlA21pbWluZARtaXQDSW50ZXJlc3RzIE1vZHVsZSBBcnRpY2xlIFBhZ2VzBHBrZwM0MDlhNDFkMi05YWRmLTM0ODctODIzZS00NzFkMTI3MWNjNzEEcG9zAzMEc2VjA240dV9pbnRlcmVzdHNfY29udGVudAR2ZXIDZDk3YTI2YjEtNWU5Ny0xMWUyLWJlZmItMGE0MTM2NWY2OWNh;_ylg=X3oDMTJyZnRvZG9wBGludGwDY2EEbGFuZwNlbi1jYQRwc3RhaWQDN2VhNjE3YTktM2UwYy0zZTM4LWE3NDAtOGI1YTE4NDQ4ZjE0BHBzdGNhdANidXNpbmVzcwRwdANzdG9yeXBhZ2U-;_ylv=3


Are these normal growing pains with the media blowing things out of
proportion ? or is the number of occurences higher than one would expect
for a plane that has been so long into development ?

In terms of the engines, since the 747-8 uses the same engines, has it
also been experiencing similar failures ? (There is far less media
interest in the new 747)

Would differences in the GE-NX used for 787 and 747-8 be sufficient to
result in very different reliability stats ?

There is mention of a lithium ion battery pack "exploding" (they really
do explode when they get too hot and catch fire). How long before the
NTSB releases its findings on this ?

Lithium ion batteries are now known to be dangerous when mishandled
(overcharging, too much heat, over discharge rates). Burning laptop
episodes not long ago taught battery designers a good lesson. Is it
possible that Boeing had already finalised designs and they were not
retrofitted with the additional battery protection circuitry that are
now required/standard ?
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JF Mezei
2013-01-17 18:17:59 UTC
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Battery issue appears more serious than just a glitch. Montréal's
LaPresse newspaper said that all 787s were grounded (but no impact on
Canadians since none come to Canada).

But the FAA web site has the less "media" and more factual statement at

> http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14233

For Immediate Release

January 16, 2013
Contact: Laura Brown or Brie Sachse
Phone: ***@faa.guv or ***@faa.guv

As a result of an in-flight, Boeing 787 battery incident earlier today
in Japan, the FAA will issue an emergency airworthiness directive (AD)
to address a potential battery fire risk in the 787 and require
operators to temporarily cease operations. Before further flight,
operators of U.S.-registered, Boeing 787 aircraft must demonstrate to
the Federal Aviation Administration (FAA) that the batteries are safe.

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

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

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

United Airlines is currently the only U.S. airline operating the 787,
with six airplanes in service. When the FAA issues an airworthiness
directive, it also alerts the international aviation community to the
action so other civil aviation authorities can take parallel action to
cover the fleets operating in their own countries.
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JF Mezei
2013-01-17 18:21:51 UTC
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Note that there are different formulations for Lithium Ion batteries,
and some (Li-Po for instance) are less prone to accidental ignition.
Again, it would all depend on what battery tech was available at the
time the specs for this subsystem in the 787 were finalized and whether
they got upgraded as new Lithium Ion technologies were introduced.

Since the FAA certified the plane in late 2011 as I recall, it SHOULD
have known about risk of fire/explosion for those batteries and made
sure there were adequate protections.
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JF Mezei
2013-01-17 18:26:13 UTC
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In another press release FAA initiates a complete review of 787 Design
and Production.

Is this something similar to how the original A320 was certified despite
serious software bugs because certification procedures hadn't foreseen
such problems ? Fuel leaks should be "legacy" technilogy and well
tested, but has the FAA ever dealt with lithium ion batteries being part
of aircraft systems ? (does the A380 use such batteries ?)


http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14213

Press Release – FAA Will Review Boeing 787 Design and Production

Print

For Immediate Release

January 11, 2013
Contact: Laura J. Brown or Brie N. Sachse
Phone: 202-555-1212

WASHINGTON – In light of a series of recent events, the FAA will conduct
a comprehensive review of the Boeing 787 critical systems, including the
design, manufacture and assembly. The purpose of the review is to
validate the work conducted during the certification process and further
ensure that the aircraft meets the FAA’s high level of safety.

“The safety of the traveling public is our top priority,” said U.S.
Transportation Secretary Ray LaHood. “This review will help us look at
the root causes and do everything we can to safeguard against similar
events in the future.”

A team of FAA and Boeing engineers and inspectors will conduct this
joint review, with an emphasis on the aircraft’s electrical power and
distribution system. The review will also examine how the electrical and
mechanical systems interact with each other.

“We are confident that the aircraft is safe. But we need to have a
complete understanding of what is happening," said FAA Administrator
Michael P. Huerta. "We are conducting the review to further ensure that
the aircraft meets our high safety standards.”

The review will be structured to provide a broader view of design,
manufacturing and assembly and will not focus exclusively on individual
events. The review is expected to begin in Seattle, but may expand to
other locations over the course of several months.

FAA technical experts logged 200,000 hours of work during the 787 type
certification and flew on numerous test flights. The FAA reviews 787
in-service events as part of our continued operational safety process.

United Airlines is currently the only U.S. airline operating the 787,
with six airplanes delivered. The worldwide in-service fleet includes 50
aircraft.
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Miles Bader
2013-01-18 00:04:41 UTC
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JF Mezei <***@vaxination.ca> writes:
> Fuel leaks should be "legacy" technilogy and well
> tested, but has the FAA ever dealt with lithium ion batteries being part
> of aircraft systems ?

The blogs I've read make it sound like the only actual issue here is
the battery thing, and that the other "problems" ("fuel leak", cracked
windshield, etc) are relatively common occurrences that don't really
have much to do with the plane model, but have gotten dragged along by
the press frenzy...

-miles

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JF Mezei
2013-01-18 08:57:16 UTC
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On 13-01-17 19:04, Miles Bader wrote:

> The blogs I've read make it sound like the only actual issue here is
> the battery thing, and that the other "problems" ("fuel leak", cracked
> windshield, etc) are relatively common occurrences that don't really
> have much to do with the plane model, but have gotten dragged along by
> the press frenzy...

Have fuel leaks been happening regularly but gone unnoticed by the media
until now ?

Does the 787 have "revolutionary" fuel handling systems ? Or are those
pretty much conventional in materials and designs ?

When they build homes, the plumbers are quite capable of welding the
pipes and ensure the house will operate without leaks for many many years.

Since Boeing has a lot of experience building planes, I would have
thought the same. Boeing would know how much torque to use on couplings
to ensure they don't come loose with vibration, they would know about
temperature extremes etc.

Why couldn't their experience with 737, 767, 747 and 777 allow Boeing to
select materials/designs that yield a reliable 787 fuel system that
lasts many many years without leaks ?


With regards to Batteries:

http://www.ntsb.gov/news/2013/130114.html
(pictures of burned battery pack)

http://www.ntsb.gov/news/2013/130108b.html
Initial finding.

In the initial finding, NTSB mentions that the APU was running at the
time the cleaning personnel were cleaning up aircraft and detected
smoke. (Shouldn't there be smoke detectors in the aft electronics rack
detect this before humans ?)

I take it that the battery is used to run an electric motor to start the
APU ? If the APU was running, it might mean that the charger was
deffective and overcharged the batteries.


The FAA AD mentions:

##
Before further flight, modify the battery system, or take other actions,
in accordance with a method approved by the Manager, Seattle Aircraft
Certification Office (ACO), FAA.
##

Meanwhile, the NTSB is conducting investigation on the Boston incident
and participating in the one that happened in Japan.

I take it that fixes allowing 787 back in service will be approved well
before NTSB issues a interim or final report on the incidents ? Will
NTSB informally advise FAA on what is needed in short term to secure
those batteries to allow 787s to return to service ? Or is there some
formal process for this ?

If one looks at the QF-32 A380 uncontained engine failure, the final
report isn't out, but the 380s has been back in service long ago. And it
hadn't taken very long for them to find the problem and solution.
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JF Mezei
2013-01-21 04:58:15 UTC
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NTSB provided a 3rd update on the 787 battery problems this sunday Jan 20th.

http://www.ntsb.gov/news/2013/130120.html

Apart from providing update on battery disassembly process, they provide
this factual piece of information:


##
Finally, examination of the flight recorder data from the JAL B-787
airplane indicate that the APU battery did not exceed its designed
voltage of 32 volts.
##

Lithium In batteries are rated at 3.7 volts, but this allows a range
from 3.0 to 4.2 (outside those voltages, the protection circuitry in
modern cells disables battery from further charge AND discharge.


The NTSB document mentions 8 cells, which indicates a total voltage of
32 volts giving average of 4.0 volts per cell, within limits. However,
if one cell was out of whack, it could have begun to overheat, heating
adjoining cells and causing them to also fail.





From Wikipedia:
http://en.wikipedia.org/wiki/Lithium-ion_battery


Safety requirements

If overheated or overcharged, Li-ion batteries may suffer thermal
runaway and cell rupture.[52] In extreme cases this can lead to
combustion. Deep discharge may short-circuit the cell, in which case
recharging would be unsafe.[citation needed] To reduce these risks,
Lithium-ion battery packs contain fail-safe circuitry that shuts down
the battery when its voltage is outside the safe range of 3–4.2 V per
cell.[35][44] When stored for long periods the small current draw of the
protection circuitry itself may drain the battery below its shut down
voltage; normal chargers are then ineffective. Many types of lithium-ion
cell cannot be charged safely below 0°C.[53]

Other safety features are required in each cell:[35]

Shut-down separator (for overtemperature)
Tear-away tab (for internal pressure)
Vent (pressure relief)
Thermal interrupt (overcurrent/overcharging)

These devices occupy useful space inside the cells, add additional
points of failure and irreversibly disable the cell when activated. They
are required because the anode produces heat during use, while the
cathode may produce oxygen. These devices and improved electrode designs
reduce/eliminate the risk of fire or explosion. Further, these features
increase costs compared to nickel metal hydride batteries, which require
only a hydrogen/oxygen recombination device (preventing damage due to
mild overcharging) and a back-up pressure valve.[44]


============

Last year, I spoke with a chinese manufacturer of Lithium cells. For
cars (China would like the business of replacing heavy and polluting
lead adic batteries with modern batteries) they prefer Lithium Polymer
batteries which require different charging logic to ensure balanced
charging. ( you can't charge 3 cells in serial with 12.6vdc , you need
to provide 4.2vdc to each cell individually because each cell may charge
at different rate)


Again, this all depends on when the battery systems for the 787 were
finalised and whether they were updated when lithium ion battery flaws
in laptops (causing fires etc) were discoered and protection circuitry
mandated right at the connection to the cell.
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JF Mezei
2013-01-27 02:37:38 UTC
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NTSB released a bit more information on the battery problems for the 787.

a issue specific page:

http://www.ntsb.gov/investigations/2013/boeing_787/boeing_787.html

Contains new images, including the APU electronics bay and the most
recent reports.

Interesting that "Aft Electronics Bay" is actually midship and not "aft".

Is this the first aircraft with APU under wings instead of being in the
tail section ?

The batteries are aren't "wired" in serial, they are bolted together
with solid metal brackets providing connection between battery terminals
to bridge 8 batteries serially. This would allow a HUGE amout of current
to flow.

More importantly, based on info in the NTSB presenttation , individual
cells do NOT have protective circuitry as is mandated for current
consumer electronics.

So a short circuit between the bars that collect the power would cause
batteries to discharge at fire producing rates since there would be no
protection.


There are also small wires form each battery terminal to the circuit
board. So the electronic would be able to monitor voltage between
positive and negative terminals of each battery. But there is no
physical way to disconnect one cell.

NTSB says that the electronics in the battery compartment are too
damaged to yield any information.

The NTSB readily says they think there has been a short circuit, but
they are not really telling if this short was inside an individual cell,
within the battery box, or outside of the box.

The NTSB has provided a copy of the press conference on Youtube. (link
on the page I linked at top of post).
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Uwe Klein
2013-01-27 10:21:07 UTC
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JF Mezei wrote:
> NTSB released a bit more information on the battery problems for the 787.
>
> a issue specific page:
>
> http://www.ntsb.gov/investigations/2013/boeing_787/boeing_787.html
>
> Contains new images, including the APU electronics bay and the most
> recent reports.
>
> Interesting that "Aft Electronics Bay" is actually midship and not "aft".
>
> Is this the first aircraft with APU under wings instead of being in the
> tail section ?

the APU is in the tailcone.

Most of the heavy switching is done in the Aft E-Bay.
.. and the P100/P200 panels are located in that place too.
See the image with the "investigator on his knees"
Front and rear are left/right in the image. behind him
is the P200 panel and behind the photograhper is the P100 one.
( or vice versa?) the modules placed left from the battery place
are said to be switching/control for electric deice.


uwe
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Roland Perry
2013-01-29 12:49:19 UTC
Permalink
In message <***@vaxination.ca>, at 21:37:38 on Sat, 26 Jan
2013, JF Mezei <***@vaxination.ca> remarked:
>There are also small wires form each battery terminal to the circuit
>board. So the electronic would be able to monitor voltage between
>positive and negative terminals of each battery. But there is no
>physical way to disconnect one cell.

Reports circulating now that the fault probably wasn't with the battery,
but perhaps with the battery charging/monitoring circuits. Which seems a
rather pedantic distinction.
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JF Mezei
2013-01-29 23:47:32 UTC
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On 13-01-29 07:49, Roland Perry wrote:

> Reports circulating now that the fault probably wasn't with the battery,
> but perhaps with the battery charging/monitoring circuits. Which seems a
> rather pedantic distinction.



NTSB may have stated they did not observe total voltage going above 32
volts. But they haven't discussed about voltage drop before/during the
event. If there was a short, the total voltage would be dropping.

Based on the photographs, I am not sure if there is any
breaker/relays/fuses between the combined batteries and the outside world.
Power from batteries is carried by metal bars, not wires. Not easy to
plug large metal bars into a logic board.

The tiny wires from each cell to the circuitry in the battery box are
too thin to "carry" a short that would cause a fire. The wires would
burn out almost instantly. There are also sensor wires from the combined
power bar to the logic board, this would seem to indicate that the power
bars themselves don't touch the logic board (otherwise there wouldn't
need to be a separate sensor wire from the power bars to the logic board).

There may be some big hunky relays at the bottom of the box before power
is allowed in/out of the box. Or maybe not.

Since this battery box is identical to the one up front which provides
emergency power to plane, the design philosophy may have been to "keep
it simple" and perhaps centralise breakers in one location so pilots can
re-instate power it breaker trips. The downside is that a short between
batteries and the first breaker will cause batteries to catch on fire.
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John Levine
2013-01-30 02:42:57 UTC
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>Reports circulating now that the fault probably wasn't with the battery,
>but perhaps with the battery charging/monitoring circuits. Which seems a
>rather pedantic distinction.

I expect it makes a major difference as to whose insurance company has
to pay for the damages.

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JF Mezei
2013-01-30 22:56:58 UTC
Permalink
On 13-01-29 21:42, John Levine wrote:
>>Reports circulating now that the fault probably wasn't with the battery,
>>but perhaps with the battery charging/monitoring circuits. Which seems a
>>rather pedantic distinction.
>
> I expect it makes a major difference as to whose insurance company has
> to pay for the damages.

Thales is main contractor hired by Boeing. Thales does the
charging/monitoring circuit and subcontracted with the japanese firm for
the battery packs.

So who'se going to sue who ? I have to assume that everyone signed off
on the design specifications. And *if* all manufactuers built their
components according to specs, can everyone sue each other ?

My guess is that Boeing will have to absorb "complaints" from airlines
about their grounded planes and delayed deliveries. From what I read,
Boeing is still building the planes but not delivering them.

However, once planes are allowed to fly again, it doesn't mean that
Boeing can deliver all the planes in its wharehouse right away. Airlines
can only absorb so many new aircraft per month. (checkout, outfitting,
training of crews etc all limit how many new aircraft you can process
and put into your schedule per month).

Some more info was released by NTSB:
##
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.
##

So this was basically a brand spanking new aircraft, so this wouldn't be
a question of "wear and tear" or aging. Had this been one of the older
aircraft in the fleet, questions about dirability of batteries could
have arisen.
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Roland Perry
2013-01-31 09:36:29 UTC
Permalink
In message <***@vaxination.ca>, at 17:56:58 on Wed, 30 Jan
2013, JF Mezei <***@vaxination.ca> remarked:

>can everyone sue each other

They can and do. Who wins is an entirely different matter.
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Uwe Klein
2013-01-31 09:52:02 UTC
Permalink
JF Mezei wrote:
> So this was basically a brand spanking new aircraft, so this wouldn't be
> a question of "wear and tear" or aging. Had this been one of the older
> aircraft in the fleet, questions about dirability of batteries could
> have arisen.

Since EIS ~ 150 batteries have been exchanged for various reasons.
10 Batteries had nonsimple faults ( like being irreversible run below threshholds.)
2 batteries had thermal runaway ( 1 with ignition of the combustible gases/electrolytes )

Having the battery level significantly lower than expected seems to be
a regular issue.

Batteries with the "no return" cutoff activated are returned to the manufacturer,
checked, <some maintainance> and (probably) returned into service.

uwe
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Miles Bader
2013-01-31 13:42:44 UTC
Permalink
Uwe Klein <***@klein-habertwedt.de> writes:
> Having the battery level significantly lower than expected seems to be
> a regular issue.

A recent newspaper story mentioned that part of this is a "user
interface" issue -- the batteries supply power for various maintenance
tasks (e.g. lights for fuel-loading, etc), and apparently it's not
uncommon for the maintenance people to inadvertently drain the
batteries...

http://seattletimes.com/html/businesstechnology/2020241385_787deadbatteriesxml.html

-miles

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Uwe Klein
2013-01-31 14:10:55 UTC
Permalink
Miles Bader wrote:
> Uwe Klein <***@klein-habertwedt.de> writes:
>
>>Having the battery level significantly lower than expected seems to be
>>a regular issue.
>
>
> A recent newspaper story mentioned that part of this is a "user
> interface" issue -- the batteries supply power for various maintenance
> tasks (e.g. lights for fuel-loading, etc), and apparently it's not
> uncommon for the maintenance people to inadvertently drain the
> batteries...
>
> http://seattletimes.com/html/businesstechnology/2020241385_787deadbatteriesxml.html
>
> -miles
>
yes.
though unexpected does imho not apply to having left the fridge door open.
that is not really "unexpected". draining the battery that way is an expected result.

Looks more like the linkage between certain actions and the activation of powersinks
is not obvious, covered by the manual or some other known explanation.

I had a smartphone once that never returned to sleep mode after having received
a text message, draining the battery in an hour or two. ( standy expectations were 48..72 hours)
you had to reboot it. then everything was Ok till the next text message arrived.

To summ it up:
should it be so easy to brick a Dreamliner !?

uwe
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Miles Bader
2013-02-01 00:00:17 UTC
Permalink
Uwe Klein <***@klein-habertwedt.de> writes:
> should it be so easy to brick a Dreamliner !?

Clearly not, and they'd obviously better address that stuff.

Still, it's a separate (and much easier to deal with) issue from the
more serious battery issues that are on the front pages now.

-miles

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JF Mezei
2013-02-01 04:58:35 UTC
Permalink
On 13-01-31 09:10, Uwe Klein wrote:

>> http://seattletimes.com/html/businesstechnology/2020241385_787deadbatteriesxml.html

> To summ it up:
> should it be so easy to brick a Dreamliner !?


Something is weird here. So there is some undervolt protection, but it
still allows batteries to be drained to "battery is permanently damaged"
because someone left the fuel door open too long.

Definitly a design problem here. Only critical systems IN FLIGHT should
be allowed to draw power below battery minimum voltages.



Considering the small size of 787 fleet flying since first delivery, 100
events where a battery had to be replaced due to damage is a large number.

In fairness, lithium ion battery chemistry degrades over time and loses
nominal capacity after 2 years. (the formulation used by Boeing may have
different longevity).

However, loss of capacity does not affect safety, only affects how much
power the battery can store when fully charged.


Non critical devices should not be allowed to draw power below the low
voltage limit. Only the most critical instruments should be allowed to
do so and only in flight. If aircraft is running on batteries only (such
as when parked overnight with APU off and no airport power), then the
power system should not allow any one device to deplete batteries when
aircraft is idle.

Consider that Lithium batteries are hard to charge when frozen. If you
leave aircraft idle overnight with no power/heating and you allow some
fuel gauges to deplete the batteries, then when they start the plane in
the morning, it may end up in flight before the batteries have had time
to warm up and begin charging up. This means that should an emergency
happen early in flight, they may not have power.


The image I get from this is that they designed those battery systems
before the issues of lithium ion batteries were known and they did not
revise those designs since then. (fact that there appears to be no
protection circuit inside each or the 8 cells is a dead giveaway of this).

It is somewhat ironic since the delays for the rest of the 787 would
have given Thales plenty of time to update the design of the battery and
power system to incorporate the latest in knowledge about behaviour and
safety of those batteries.


They may institute some temporary maintenance/operations procedures (for
instance requiring that 78s7 overnight "plugged in" to airport supplied
power to prevent battery depletion.

But my guess is that they will want to have some redesign of the logic
which allows power to flow out of batteries (don't power anything below
battery voltage unless in flight emergency), and probably mandate that
each cell has its own protection circuit between the leads and the
battery itself.
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Uwe Klein
2013-02-01 08:23:24 UTC
Permalink
JF Mezei wrote:
> On 13-01-31 09:10, Uwe Klein wrote:
>
>
>>>http://seattletimes.com/html/businesstechnology/2020241385_787deadbatteriesxml.html
>
>
>>To summ it up:
>>should it be so easy to brick a Dreamliner !?
>
>
OK, to work ;-)
>
> Something is weird here. So there is some undervolt protection, but it
> still allows batteries to be drained to "battery is permanently damaged"
> because someone left the fuel door open too long.
The things have "popped their internal fuse". It is open if they are damaged.
But the intrinsic properties are such that further usage is a game of chance.

> Considering the small size of 787 fleet flying since first delivery, 100
> events where a battery had to be replaced due to damage is a large number.
YES. Most of the frames were delivered in Q3/_Q4_ of 2012.
>
> In fairness, lithium ion battery chemistry degrades over time and loses
> nominal capacity after 2 years. (the formulation used by Boeing may have
> different longevity).
2 years is for consumer products _and_ Li-Po(lymer) technology.

Airbus and Lange Aviation expect 3000SAE cycles or 20years service life
in a controlled ( 20°C environment. ) from the product they use : Saft VL45E
cylindrical cells.
>
> However, loss of capacity does not affect safety, only affects how much
> power the battery can store when fully charged.
loss of capacity is in lockstep with increase in impedance.
>
>
> Non critical devices should not be allowed to draw power below the low
> voltage limit. Only the most critical instruments should be allowed to
> do so and only in flight. If aircraft is running on batteries only (such
> as when parked overnight with APU off and no airport power), then the
> power system should not allow any one device to deplete batteries when
> aircraft is idle.
>
> Consider that Lithium batteries are hard to charge when frozen. If you
> leave aircraft idle overnight with no power/heating and you allow some
> fuel gauges to deplete the batteries, then when they start the plane in
> the morning, it may end up in flight before the batteries have had time
> to warm up and begin charging up. This means that should an emergency
> happen early in flight, they may not have power.
Lange Aviation uses the Saft cells for electric propulsion.
Their battery pack sits in the leading edge of the Antares 20
in a carefully controlled environment ( heater/cooler, 20°C )
>
IMHO Boeing hogs the parametric envelope in every direction.
the e-Bays are hot they charge to the brim, they charge at the highest rate
they discharge at high rates and very deep.
>
> The image I get from this is that they designed those battery systems
> before the issues of lithium ion batteries were known and they did not
> revise those designs since then. (fact that there appears to be no
> protection circuit inside each or the 8 cells is a dead giveaway of this).

The technological issues for each Li-Ion variant were always known.
Boeing choose the variant with the best theoretical performance
ignoring all caveats and abusing the battery in a way that might be
acceptable for NiCd or LeadAcid but certainly not for _any_ Li-Ion chemistry.

Airbus and Lange decided earlier and for a less fickle cell setup.
The more benign chemistry, the more robust formfactor ( cylindrical cells )
and choose to handle the battery in a more "respectfull" way.
>
> It is somewhat ironic since the delays for the rest of the 787 would
> have given Thales plenty of time to update the design of the battery and
> power system to incorporate the latest in knowledge about behaviour and
> safety of those batteries.
Everybody was busy fixing all the other problems on that bird.
Everything that only had reduced service life was seen as a godsent gift.
>
>
> They may institute some temporary maintenance/operations procedures (for
> instance requiring that 78s7 overnight "plugged in" to airport supplied
> power to prevent battery depletion.

A peripheral issue seems to be that older ground power units
create significant problems when being attached to the 787.
Thus the preference is to start from battery.
>
> But my guess is that they will want to have some redesign of the logic
> which allows power to flow out of batteries (don't power anything below
> battery voltage unless in flight emergency), and probably mandate that
> each cell has its own protection circuit between the leads and the
> battery itself.

A lot of the fixes won't be made public.

And those published will get a floury explanation attached like so
many other design decission on this bird.

uwe
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JF Mezei
2013-01-31 17:36:11 UTC
Permalink
On 13-01-31 04:52, Uwe Klein wrote:

> Since EIS ~ 150 batteries have been exchanged for various reasons.
> 10 Batteries had nonsimple faults ( like being irreversible run below threshholds.)
> 2 batteries had thermal runaway ( 1 with ignition of the combustible gases/electrolytes )

If you are in engine-out situation, the RAT failed to deploy and need
power from batteries as long as possible to increase odds of landing
instead of crashing, I can see why they would allow batteries to run
below treshold even if it means batteries become inop afterwards.

Emergency batteries in a plane have a different mission. Not the same as
your laptop with the fancy lighted fruit logo shutting down while you
are at Starbucks.

However, if this situation happens during normal day to day operations,
then there is a problem. There should be battery protection circuitry
which protects during day to day, but which can automatically be lifted
in an emergency.

A modern laptop has circuitry which will first put laptop to sleep.
Before voltage gets to the undervolt limit, the laptop will write RAM to
disk and fully shutdown before the battery's own protection kicks in.

> Batteries with the "no return" cutoff activated are returned to the manufacturer,
> checked, <some maintainance> and (probably) returned into service.

When you say "no return cutoff" do you mean that there is circuitry that
cuts off the battery in an undervolt situation ?

It was my understanding that a lithium battery that has been allowed to
be undervolt has its chemistry altered and loses much of its ability to
store power. This is why modern matteries have cicuitry in the battery
to cut off output before it reaches that voltage limit. The circuitry
will operate again after the battery is being charged oand voltage above
the treshold.
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Uwe Klein
2013-01-31 18:33:58 UTC
Permalink
JF Mezei wrote:
> On 13-01-31 04:52, Uwe Klein wrote:
>
>
>>Since EIS ~ 150 batteries have been exchanged for various reasons.
>>10 Batteries had nonsimple faults ( like being irreversible run below threshholds.)
>>2 batteries had thermal runaway ( 1 with ignition of the combustible gases/electrolytes )
>
>
> If you are in engine-out situation, the RAT failed to deploy and need
> power from batteries as long as possible to increase odds of landing
> instead of crashing, I can see why they would allow batteries to run
> below treshold even if it means batteries become inop afterwards.

In an emergency I would _mandate_ that the battery can be run into oblivion.

If it makes the difference a fire is more acceptable in the last throes of
an emergency than a catastrophy because those last 3% of juice
were not accessible.
If that does not suffice your toast anyway.

>
>>Batteries with the "no return" cutoff activated are returned to the manufacturer,
>> checked, <some maintainance> and (probably) returned into service.
>
>
> When you say "no return cutoff" do you mean that there is circuitry that
> cuts off the battery in an undervolt situation ?

Yes. A Circuit internal to the battery.
For the regular day to day use case the battery becomes an unservicable brick.

The brighter thing to do imho would have been to cut off the battery
internally at say 15%/absolute allowable minimum ( status quo )
but also have the external electronics take down the system at say 20%
to be able to boot the system from groundpower to charge the battery.

>
> It was my understanding that a lithium battery that has been allowed to
> be undervolt has its chemistry altered and loses much of its ability to
> store power.
If the cell voltage ever goes below ~2.0V copper from the electrodes
difuses as ions into the electrolyte. If the voltage goes up again
these copper ions loose their charge and remain as copper particles
in the active part of the battery.

Guess what effects conducting particles have in that area ;-)
You have just created a time bomb if use is continued.


> This is why modern matteries have cicuitry in the battery
> to cut off output before it reaches that voltage limit. The circuitry
> will operate again after the battery is being charged oand voltage above
> the treshold.
Exactly.
Only in this case it is "savety first" and the battery wins a
round trip to the manufacturer. Which is OK imho.

G!
uwe
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JF Mezei
2013-01-31 22:50:17 UTC
Permalink
On 13-01-31 13:33, Uwe Klein wrote:

> In an emergency I would _mandate_ that the battery can be run into oblivion.

But it becomes a question of whether you can automate "this is an
emergency, bypass safety protocols", or whether it would take action
from pilots to override those safeties (press some button in cockpit).


> Yes. A Circuit internal to the battery.

From what I have seen of the NTSB pictures, there is no circuitry inside
the 3.7v cells. If "low voltage cutoff" is done on the combined output,
it becomes possible for total voltage to be within the limits while an
individual cell is lower than limit (consider one cell at 1.9 and the
other at 2.1, total voltage is at 4 and thus acceptable even though one
cell is below 2.0.

I know that for LiFePo batteries which are "safer" ni terms of fire etc,
have a problem where multple batteries in series may not discharge at
same rate and this complicates charging process when not all batteries
are at same voltage.

Not sure if the Lithium Cobalt Oxide batteries used on 787 exhibit
voltage imbalance issues.

Wikipedia even setup a page on those batteries:
https://en.wikipedia.org/wiki/Lithium_cobalt_oxide

> The brighter thing to do imho would have been to cut off the battery
> internally at say 15%/absolute allowable minimum ( status quo )
> but also have the external electronics take down the system at say 20%
> to be able to boot the system from groundpower to charge the battery.

Looking at the large bars of solid metal linking the battery terminals,
I would say they are designed for high current loads (such as powering
up the APU. This may make integrating protection circuits in each cell
harder since those circuits would have to be built to handle huge
current. (that is different from your average laptop battery where
you're looking at perhaps 60 watts max).


> If the cell voltage ever goes below ~2.0V copper from the electrodes
> difuses as ions into the electrolyte. If the voltage goes up again
> these copper ions loose their charge and remain as copper particles
> in the active part of the battery.

So, if undervolt situation had happened in the past, would current FDR
data around the time of the fire reflect any pecular cell behaviour ?
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Uwe Klein
2013-02-01 08:32:32 UTC
Permalink
JF Mezei wrote:
> On 13-01-31 13:33, Uwe Klein wrote:
>
>
>>In an emergency I would _mandate_ that the battery can be run into oblivion.
>
>
> But it becomes a question of whether you can automate "this is an
> emergency, bypass safety protocols", or whether it would take action
> from pilots to override those safeties (press some button in cockpit).
>
>
>
>>Yes. A Circuit internal to the battery.
>
>
> From what I have seen of the NTSB pictures, there is no circuitry inside
> the 3.7v cells. If "low voltage cutoff" is done on the combined output,
> it becomes possible for total voltage to be within the limits while an
> individual cell is lower than limit (consider one cell at 1.9 and the
> other at 2.1, total voltage is at 4 and thus acceptable even though one
> cell is below 2.0.

The cells are specced at 5C max discharge i.e. 65A * 5 = 325A

See the small white wires (~25..30 ) attached to the cells and interconnections
that go to the 2 stacked pcbs at the front? Those are the leads to supervise
cell voltages and temperatures. ( It is open if there is a balancing
function build in.)

Having the supervisory stuff intrinsic to each cell is usefull for
"loose" cells only.

In the frontal bottom there seems to be 2 cut off contacts that
disconnect the batteryvoltage from the outside in case of cutoff.
( see the various detailed pics now floating around the internet )

uwe
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JF Mezei
2013-02-08 01:49:42 UTC
Permalink
NTSB made a new press release today:

http://www.ntsb.gov/news/2013/130207.html

basically, one of the 8 cells ran amok, overheated and caused the
adjacent cells to also have thermal runaway.

The problem originated within that cell. It was not an external short
circuit.

NTSB to issue interi report within 30 days.
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JF Mezei
2013-02-18 18:52:28 UTC
Permalink
Airbus announces Plan B: 350 to use Nickel Cadmium batteries instead of
Lithium Ion.

> http://www.airbus.com/newsevents/news-events-single/detail/airbus-activates-plan-b-for-the-a350-xwb-batteries/


http://www.bbc.co.uk/news/business-21477126


So basically, due to uncertainty about Lithium Ion, they are going NiCd
(even though flight tests will be with the Lithium Ion batteries).

I am curious as to why Nickel Cadmium instead of Nickel Metal Hydride ?
Are NiMh considered unsafe ? It was my impression that NiMh were far
superior than the old NiCd tech ?

Also, I am somewhat susprised that they wouldn't be looking at various
newer Lithium formulations, some of them being quite safe.
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Uwe Klein
2013-02-18 20:09:03 UTC
Permalink
JF Mezei wrote:
> Airbus announces Plan B: 350 to use Nickel Cadmium batteries instead of
> Lithium Ion.

Yes, Boeing has transformed the certification environment for Li-Ion of
any ilk into a bottomless bog.
>
>
>>http://www.airbus.com/newsevents/news-events-single/detail/airbus-activates-plan-b-for-the-a350-xwb-batteries/
>
>
>
> http://www.bbc.co.uk/news/business-21477126
>
>
> So basically, due to uncertainty about Lithium Ion, they are going NiCd
> (even though flight tests will be with the Lithium Ion batteries).
>
> I am curious as to why Nickel Cadmium instead of Nickel Metal Hydride ?
> Are NiMh considered unsafe ? It was my impression that NiMh were far
> superior than the old NiCd tech ?
>
> Also, I am somewhat susprised that they wouldn't be looking at various
> newer Lithium formulations, some of them being quite safe.

COTS Common of the shelf parts.

And they see it as an interim solution until the smoke clears
to avoid surprises and forced short term changes.
Maybe even a dual cert well integrated Li-Ion for EASA cert
and NiCd for a burned and angsty FAA.

Looks like Airbus was carefull to not taylor their systems too tightly
to Li-Ion battery properties.
Afaics they may have planned that in the next generation.

A: Fly Li-Ion in less demanding usage : ( emergency lighting A380 )
B: Fly Li-Ion in a central function but do not utilise special properties ( main and aux batteries
A350 )
C: Fly Li-Ion in all functions and utilise specific properties.
(.. my thinking on how Airbus thinks. They never jumped into anything unprepared and unexperienced
like Boeing did with the 787 )

uwe
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JF Mezei
2013-02-18 21:29:18 UTC
Permalink
On 13-02-18 15:09, Uwe Klein wrote:

> Yes, Boeing has transformed the certification environment for Li-Ion of
> any ilk into a bottomless bog.

Look to me like there was an FAA failure to setup proper battery
testing. Airbus is lucky that it is behind Boeing on this type of aircraft.

> Looks like Airbus was carefull to not taylor their systems too tightly
> to Li-Ion battery properties.
> Afaics they may have planned that in the next generation.

I am not sure this is fair. Had the Boeing incidents started to happen
after the 350 was in production, I think both manufacturers would have
been hit by same problem.

> A: Fly Li-Ion in less demanding usage : ( emergency lighting A380 )
> B: Fly Li-Ion in a central function but do not utilise special properties ( main and aux batteries
> A350 )
> C: Fly Li-Ion in all functions and utilise specific properties.

Since any Li-Ion battery, small or big, can cause a fire, I am not sure
that type of use would be a criteria to decide whether it is acceptable
for airline use or not. As soon as you have charging circuitry, or
chance of a short circuit, batteries can heat, explode and/or catch fire.

There are however newer formulations which are far more immune to
thermal runaway than the "standard" Lithium ion used for the 787.

And my guess is that Boeing is likely working on a NiCd battery pack
Basically 25 or 26 1.2vdc cells will do the trick of 8 3.7vdc cells.
This would allow the plane to go back into flight and deliveries while
Boeing and Airbus work out Li-Ion issues.
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Uwe Klein
2013-02-18 22:20:34 UTC
Permalink
JF Mezei wrote:
> On 13-02-18 15:09, Uwe Klein wrote:
>
>
>>Yes, Boeing has transformed the certification environment for Li-Ion of
>>any ilk into a bottomless bog.
>
>
> Look to me like there was an FAA failure to setup proper battery
> testing. Airbus is lucky that it is behind Boeing on this type of aircraft.

FAA was removed one step further out of the certification process.
IMU Boeing did the certification and told the FAA "that it was OK"

Airbus was well prepared but was mired by Boeing.

>
>>Looks like Airbus was carefull to not taylor their systems too tightly
>>to Li-Ion battery properties.
>>Afaics they may have planned that in the next generation.
>
>
> I am not sure this is fair. Had the Boeing incidents started to happen
> after the 350 was in production, I think both manufacturers would have
> been hit by same problem.

I don't think so. Airbus seems to have been very carefull to avoid known
issues with Li-Ion technology. While Boeing selected in every degree of
freedom the more risky solution ( or just ignored risk )
and ommited saveguards ( see the battery box and internal setup )
Airbus can be found on the obverse side of available leeway.
>
>
>>A: Fly Li-Ion in less demanding usage : ( emergency lighting A380 )
>>B: Fly Li-Ion in a central function but do not utilise special properties ( main and aux batteries
>>A350 )
>>C: Fly Li-Ion in all functions and utilise specific properties.
>
>
> Since any Li-Ion battery, small or big, can cause a fire, I am not sure
> that type of use would be a criteria to decide whether it is acceptable
> for airline use or not. As soon as you have charging circuitry, or
> chance of a short circuit, batteries can heat, explode and/or catch fire.

Esentially NiCd started with similar issues and has been matured enough to be
deemed save enough today. Boeing was market leader in that timeframe.
So they should have that corporate wisdom at hand on what can happen
and how to ameliorate problems.
>
> There are however newer formulations which are far more immune to
> thermal runaway than the "standard" Lithium ion used for the 787.

yes.
Same for formfactor.

The prismatic cells with multiple "bales" of active material
are seen as significantly less robust ( especially in variable pressure environments )
than cylindrical cells ( SAFT, used by Airbus and forex Lange Aviation on
their electric sailplane Antares 20,
( see http://www.lange-aviation.com/htm/english/products/antares_20e/battery_system.html )
also military and space applications )
>
> And my guess is that Boeing is likely working on a NiCd battery pack
> Basically 25 or 26 1.2vdc cells will do the trick of 8 3.7vdc cells.
> This would allow the plane to go back into flight and deliveries while
> Boeing and Airbus work out Li-Ion issues.

Could be.

Though Boeing has been adamant that Li-Ion battery is deeply integrated.
i.e. they indicate that intrinsic properties of these batteries are essential
to the 787 electrical system. ( I am partial to this statement, a lot
of Boeing tall statements have dissolved under scrutiny, but .. )

In my opinion Airbus has a workable solution.
There is a funny trend by some to see what is problematic for Boeing
to be also unachievable for Airbus.

This is naive ( or jingoistic YMMV )


uwe

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JF Mezei
2013-02-19 22:38:14 UTC
Permalink
On 13-02-18 17:20, Uwe Klein wrote:

> FAA was removed one step further out of the certification process.
> IMU Boeing did the certification and told the FAA "that it was OK"

It is still an FAA failure in my opinion. Considering that the FAA
itself was aware of the potential danger of Lithium Ion batteries due to
the many recall of laptop battteries, they should have insisted on
having more active role in their certification.

Last summer, I evaluated lithium ion batteries (charged via solar panel)
for a bike trip. It was made very clear to me that every cell needed
protection circuitry right at the cell above and beyond a properly
designed charging circuit. There are also youtube videos that show what
happens to lithium batteries when misused. Yes, they explode.

If *I* know that, then I would have expected the FAA to know that as well.

Considering the Boeing design have all the cells hardwired together with
metal plates that can carry huge amount of power and with no protective
circuitry for each cell, I would have thought it should have rung a bell
or two at the FAA.

Perhaps 2 separate sets of 8 smaller batteries with protective circuitry
would have provided what is needed since if one set fails because
protective circuitry has cut power off, the other set will still provide
enough power to run emergency stuff.

Looks to me like the solution approved by Boeing was akin to placing a
penny in a fuse box to make sure the fuse never blows because current
flows through the penny.

In the case, *IF* a short happened inside one cell by itself, then there
is nothing a protective circuitry could have helped with since the
problem then became generation of heat by one battery corrupting
adjacent batteries into getting into thermal runaway themselves.



> Airbus was well prepared but was mired by Boeing.

I gues one problem for them is that certification authorities will wait
to see the result of the 787 investigation before setting new standards
for lithium ion batteries, and until this happens, Airbus can't really
know how far they need to go.

> I don't think so. Airbus seems to have been very carefull to avoid known
> issues with Li-Ion technology.

Since I haven't seen how Airbus has implenented their use of lithium ion
batteries, I can't comment. The A380 predates the learning about dangers
of lithium ion, so I am curious to see how Airbus did it and whether
they ended up updating the design before first delivery to add more
safety features.

For the 350, they would have known about dangers of lithium ion during
the design phase, so there is a possibility of having implemented proper
safety features. This is where being late to the game can have an advantage.

What is interesting is that Airbus will use lithium batteries in the
planes used for certification. (the test aircraft). This leads me to
believe that they are confident that by the time authorities look at the
350 batteries for certification, the 787 issues will have been
documented and authorities will find Airbus already compliant with
recommendations.

> The prismatic cells with multiple "bales" of active material
> are seen as significantly less robust ( especially in variable pressure environments )
> than cylindrical cells ( SAFT, used by Airbus and forex Lange Aviation on
> their electric sailplane Antares 20,
> ( see http://www.lange-aviation.com/htm/english/products/antares_20e/battery_system.html )
> also military and space applications )

But aren't cylindrical batteries less space/weight efficient ? Is the
material rolled up inside instead of being "fan folded" in a rectangular
form factor ?

I note that on the antares, you see the protective circuitry for each
battery. Something lacking in the boeing design.

> Though Boeing has been adamant that Li-Ion battery is deeply integrated.
> i.e. they indicate that intrinsic properties of these batteries are essential
> to the 787 electrical system.

I can see the need for high discharge rate for APU startup. (but this
can be obtained by safer Lithium Phosphate batteries which are less
likekly to ignite).

If the battery system is set for 30 volts DC, it is very likely that any
sensitive electronics have their own DC/DC converters to bring voltage
down to electronic levels. In such a case, whether they are supplied by
29, 30 or 31 vdc wouldn't really matter because the DC/DC converters
automatically compensate to provide stable voltage to the device.


> In my opinion Airbus has a workable solution.

If Airbus is able to offer a NiCd solution as plan B, it is quite likely
that it is fairly easy to retrofit the 787 with NiCD batteries, at least
in the interim to get those planes off the ground until permanent
solution is found.

Also of concern is the news that the batteries have had to be replaced
very frequently. So it would seem to me that on top of the serious
safety issue, Boeing would also want to tackle the unreliable nature of
their batteries that need to be replaced frequently.
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JF Mezei
2013-02-23 06:16:36 UTC
Permalink
Boeing 'set to offer plan to fix Dreamliner battery'
http://www.bbc.co.uk/news/business-21548113


Basically, Boeing is proposing to FAA to build a better battery box.

-ceramid insulation between cells
-stainless steel box with vent tube to outside to funnel fumes/flames
-wiring changes
-self torqing screws that won't come loose
-battery changes to prevent moisture and vibration problems.
-monitoring of temperature and individual cells (I though voltage was
already monitored based on those small wires from each cell to the
circuit board - perhaps they will now send this data to the FDR ?)

Some see this is to be see as short term fix, with no discussion on
long term fix or hange in battery chemistry. However, some reports say
that this is the only think Boeing is working on.

from reuters:
##
"It's a bit tone deaf to propose containment and management when the
political winds are favoring an elimination of the risk,"
##
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Uwe Klein
2013-02-23 10:24:04 UTC
Permalink
JF Mezei wrote:
> Boeing 'set to offer plan to fix Dreamliner battery'
> http://www.bbc.co.uk/news/business-21548113
>
>
> Basically, Boeing is proposing to FAA to build a better battery box.
>
> -ceramid insulation between cells
> -stainless steel box with vent tube to outside to funnel fumes/flames
> -wiring changes
> -self torqing screws that won't come loose
> -battery changes to prevent moisture and vibration problems.
> -monitoring of temperature and individual cells (I though voltage was
> already monitored based on those small wires from each cell to the
> circuit board - perhaps they will now send this data to the FDR ?)
>
> Some see this is to be see as short term fix, with no discussion on
> long term fix or hange in battery chemistry. However, some reports say
> that this is the only think Boeing is working on.
>
> from reuters:
> ##
> "It's a bit tone deaf to propose containment and management when the
> political winds are favoring an elimination of the risk,"
> ##
reuters point : Not quite .

It is Boeings third push to force FAA's hand afaics.
(and they first "informed" the political levels above FAA, how insidious )

a containment won't change the batteries being not available.
The current setup provided
for 2 battery failures in less than 45,000 h utilisation.

Reliable batteries are required for ETOPS.
It has not been proven that both batteries are independently going into fault.

Chances are high ( from 1/2e3 per 10h flight to 1/4e6 per 10h flight )
to loose both batteries in a 10h flight. unacceptable.

Without knowing what caused the failures
changes cannot accertain improvements on reliability.

The original FAA requirements demanded a battery/cell fault to have
<1/10e6 h probability _under condition_ that a fault would be contained.
( reduced from 1/1e9 ~= "does not happen in lifetime of product" )

Boeing's proposition would provide for "contained fault"
but not for <1/10e6 h probability

probability still is 2/45e3 h

also looming : sequestration and thus FAA reduced workforce

uwe
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JF Mezei
2013-02-23 16:39:25 UTC
Permalink
On 13-02-23 05:24, Uwe Klein wrote:

> a containment won't change the batteries being not available.
> The current setup provided
> for 2 battery failures in less than 45,000 h utilisation.

If the cockpit batteries have failed, can the cockpit in an emergency
draw power from the APU batteries ? (and does the vice versa apply as
well ?)

> Reliable batteries are required for ETOPS.

I would think they would be required for any flight in cases of engine
out and failed RAT. Is there a requirement that the RAT be able to
supply all electrical power (and hydraulics) for emergency landing ? Or
can it be a combination of RAT and battery when you have an all engines
out situation ?

It should be noted that all engine out situation is not as uncommon as
one would think, ranging for fuel errors (AC Gimli, Air Transat),
volcano (BA) and highjackers (ethiopian 767).

> It has not been proven that both batteries are independently going into fault.

This is more of a "system" issue than battery issue. For instance, air
conditioners go onto battery power draw too much which cause the APU
battery fuses to trip and air conditioners then switch over to the
cockpit battery doing the same.

This is something the FAA/NTSB should be able to check based on logic
used for the power system.

> Without knowing what caused the failures
> changes cannot accertain improvements on reliability.

The changes proposed by Boeing seem to address failure containment only.
They don't address failure. And in fairness, until they know why those
batteries are so unreliable, they can't really find a solution.

It isn't just the 2 incidents that are at issue, but also the news that
the airlines have had to frequency replace those battery packs.


> Boeing's proposition would provide for "contained fault"
> but not for <1/10e6 h probability

But this solution may be sufficient to put aircraft back into service
while Boeing/FAA/NTSB work out exactly what is wrong with batteries,
something which could take a long time. (and putting it back into
service would also provide additional data on battery faults, especially
if they start recording individual cell data (voltage, temperature)

The 787 has now been grounded for longer than the DC-10.


What bugs me in this is that Boeing isn't discussing battery chemistry
change. Even for the APU, wouldn't other chemistries still be able to
supply the Amperage needed to start the APU ?

How difficult would it be to take battery designs from the 777 and put
them into the 787 until this mess is sorted out ? They may be heavier,
but wouldn't they be able to do the job ?


In terms of the cockpit ones, wouldn't electronics in the cockpit all
have DC/DC converters from the roughly 30 volts supply by batteries ? If
so, variance of a few volts wouldn't matter.
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Uwe Klein
2013-02-23 17:20:09 UTC
Permalink
JF Mezei wrote:
> On 13-02-23 05:24, Uwe Klein wrote:
>
>
>>a containment won't change the batteries being not available.
>>The current setup provided
>> for 2 battery failures in less than 45,000 h utilisation.
>
>
> If the cockpit batteries have failed, can the cockpit in an emergency
> draw power from the APU batteries ? (and does the vice versa apply as
> well ?)

APU and main battery are the same partnumber, exchangeable.
My guess is that each battery supplies one independent 28V Bus.
( A380, A350 have 4 batteries that each supply one of 4 independent DC busses )
>
>
>>Reliable batteries are required for ETOPS.
>
>
> I would think they would be required for any flight in cases of engine
> out and failed RAT. Is there a requirement that the RAT be able to
> supply all electrical power (and hydraulics) for emergency landing ?

Battery seems to be required for APU start. APU will switch off on battery fault.
( Ms. Hersmann in some public hearing )

> Or
> can it be a combination of RAT and battery when you have an all engines
> out situation ?
battery is "save" power. RAT power has delay ( detect power loss , deploy turbine
have it online )

>
> It should be noted that all engine out situation is not as uncommon as
> one would think, ranging for fuel errors (AC Gimli, Air Transat),
> volcano (BA) and highjackers (ethiopian 767).
>
>
>>It has not been proven that both batteries are independently going into fault.
>
>
> This is more of a "system" issue than battery issue. For instance, air
> conditioners go onto battery power draw too much which cause the APU
> battery fuses to trip and air conditioners then switch over to the
> cockpit battery doing the same.
Hmm, one fault case is that APU wiring enables a short circuit between batteries.
_Damaging both batteries_ in one go. ( Wrong wiring detected by japaneese authorieties.)

Even if the batteries are only "slightly" damged i.e. some slight imperfection
introduct into one or more cells from this in further use
each battery may develope this into a full size fault and go postal ( forex during final charging.)
>
> This is something the FAA/NTSB should be able to check based on logic
> used for the power system.
>
YES.
>
>>Without knowing what caused the failures
>>changes cannot accertain improvements on reliability.
>
>
> The changes proposed by Boeing seem to address failure containment only.
> They don't address failure. And in fairness, until they know why those
> batteries are so unreliable, they can't really find a solution.
>
> It isn't just the 2 incidents that are at issue, but also the news that
> the airlines have had to frequency replace those battery packs.
>
Yes.
Battery abuse seems to be agive.

Most batteries were run down below internal cutoff levels (activating before
damaging levels are reached ). ( reset only in factory )

Some batteries also shew single cell voltages below expected and save values.
>
>
>>Boeing's proposition would provide for "contained fault"
>>but not for <1/10e6 h probability
>
>
> But this solution may be sufficient to put aircraft back into service
> while Boeing/FAA/NTSB work out exactly what is wrong with batteries,
> something which could take a long time. (and putting it back into
> service would also provide additional data on battery faults, especially
> if they start recording individual cell data (voltage, temperature)
>
> The 787 has now been grounded for longer than the DC-10.
>
>
> What bugs me in this is that Boeing isn't discussing battery chemistry
> change. Even for the APU, wouldn't other chemistries still be able to
> supply the Amperage needed to start the APU ?

Out of scope for the timeframe that Boeing is looking at.
You can't change that like you can press a bunch of machinist to build
bomb proof battery shelters

>
> How difficult would it be to take battery designs from the 777 and put
> them into the 787 until this mess is sorted out ? They may be heavier,
> but wouldn't they be able to do the job ?
>
>
> In terms of the cockpit ones, wouldn't electronics in the cockpit all
> have DC/DC converters from the roughly 30 volts supply by batteries ? If
> so, variance of a few volts wouldn't matter.
yes. acceptable voltage range is of importance here.

uwe

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Roland Perry
2013-02-18 21:39:35 UTC
Permalink
In message <0ceav9-***@klein-habertwedt.de>, at 21:09:03 on Mon, 18
Feb 2013, Uwe Klein <***@klein-habertwedt.de> remarked:

>And they see it as an interim solution until the smoke clears

A very pertinent metaphor.
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A Guy Called Tyketto
2013-02-26 05:16:34 UTC
Permalink
Boeing now has a bigger problem than just the B787 battery. What
could be bigger than that, and airlines losing nearly $50,000/day on the
B787 being grounded?

Simple: Parking Space.

http://www.nytimes.com/2013/02/20/realestate/commercial/to-boeings-list-of-dreamliner-headaches-add-parking.html

New Dreamliner Headache: Parking Space
By CHRISTINE NEGRONI

With the Federal Aviation Administration.s grounding of the 787
Dreamliner fleet in its fifth week, Boeing now faces a problem of where
to store the airplanes that continue to roll off the assembly line at
its giant factory 30 miles north of Seattle.

Boeing, reluctant to shut down its production lines at Everett, Wash.,
and at a factory in Charleston, S.C., is producing 787s at a rate of
slightly more than one a week. At the time the fleet was grounded, 50
Dreamliners were in service.

"We have adequate space today in Everett to accommodate our production
airplanes," Marc Birtel, a spokesman for Boeing, said in an e-mail, "and
we won.t speculate publicly on limitations in the future."

But people familiar with Boeing's plans say two of the nation's largest
commercial airplane storage companies have been asked by Boeing for
space to park other models of airplanes that for one reason or another
cannot be delivered immediately to customers.

Since the 787 needs special F.A.A. permission to fly, these people said
Boeing is trying to make room for the Dreamliners.

When Mary Kirby, the editor of an aviation magazine, attended an
industry conference in Washington last week, she could not resist taking
a drive by Paine Field in Everett.

She said she was shocked at what she saw: "Parked Boeing 787s are
everywhere."

Two likely storage destinations for planes are Pratt & Whitney.s
Southern California Aviation in Victorville, Calif., and Marana
Aerospace Solutions in Marana, Ariz. The Victorville location has space
for 330 airplanes, according to Leo Makowski, a spokesman for Pratt &
Whitney. Only about half of the space is occupied, he said.

--snip--

So in short, with the B777, B737 (including MAX), and B787 lines
still going, KPAE is running out of parking space. If they don't get a
solution going, approved, and fast, they'll have some major jostling
around to do at the field to get others off the assembly line, otherwise
all aseembly lines will be impacted.

BL.
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JF Mezei
2013-02-26 08:22:45 UTC
Permalink
On 13-02-26 00:16, A Guy Called Tyketto wrote:

> So in short, with the B777, B737 (including MAX), and B787 lines
> still going, KPAE is running out of parking space. If they don't get a
> solution going, approved, and fast, they'll have some major jostling
> around to do at the field to get others off the assembly line, otherwise
> all aseembly lines will be impacted.

On 9-11, I was able to go cycling behind Dorval airport (they hadn't yet
realised they should close that road :-)

Air Canada managed to pack its planes into its maintenance area very
very very tightly.

Based on the picture in the NYT article, it looks like tail to nose
parking. very space inefficient. Park planes in slight diagonal so that
the tail of plane almost touches the left wing of the plane behind it
(and same for plane ahead).

BTW, many media outlets report that airlines such as ANA cancel flights
up to X date. And right now, may and June appear to be the dates before
which the airlines don't expect the 787 to come back into service.

Question: Say Boeing gets those new battery containers. I can understand
FAA and others not wanting commercial flights with passengers on them.

But can th FAA authorise some test flights or even some ferry flights ?
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Uwe Klein
2013-02-26 14:10:56 UTC
Permalink
A Guy Called Tyketto wrote:
> Boeing now has a bigger problem than just the B787 battery. What
> could be bigger than that, and airlines losing nearly $50,000/day on the
> B787 being grounded?
>
> Simple: Parking Space.

They should have started out with ~45 still undelivered frames.
( various L/N starting from low numbers including the terrible teens )

every month brings another 5 at the current production rate.

LOT has extended their 767 lease on Boeings urging till October.

10 month @ 5/per are 100 additional frames.

Another potential Boeing record: 150 undelivered planes of one type.


Much more interesting: How will the 787-9 developement continue.

First Flight is ( was ?) planned for 2013H2.

uwe
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JF Mezei
2013-02-27 06:37:29 UTC
Permalink
On 13-02-26 09:10, Uwe Klein wrote:

> LOT has extended their 767 lease on Boeings urging till October.

But this *could* be due to LOT agreeing to shift delivery slots to a
later time so that Boeing could deliver on-time to some other airline.

Unless you're a fly one the wall at the meeting where Boeing explains to
the LOT president what is really happening, there is no way to know for
sure.

> Another potential Boeing record: 150 undelivered planes of one type.

The other problem is that airlines can only accept so many new aircraft
of a new type per month. They need to take X number of pilots off-line
so they can get their training and get spots in slot limited flight
simulators, as well as do some custom finishing preparations to aircraft.

So even if Boeing has 10 aircraft ready to be delivered to United, it
doesn't mean United will take all 10 the minute the 787 gets the right
to fly again.

The goal would be to shift production slots so that you only build 2-3
aircraft per airline during the time you can't deliver them so that the
second FAA lifts the ban, each airline will accept those 2 or 3 and thus
empty the parking lot with record number of deliveries.

But shifting production slots at last minute is not easy because so many
of the airline-custom parts are "just in time" and suppliers originally
told to deliver them X months down the line.

So this will be a test to see just how much commonality Boeing was able
to put between each airline customer to ease production slot switching.


The temporary fix may allow 78s7 back in the air, but how much downtime
will be required when a permanent fix arrives many months down the road ?
Is there a point in accepting 787s now if months down the road, they
have to be off-line for a few weeks while their electrical systems is
reworked ? If the planned permanent changes can be done overnight with
battery swaps and control system swaps, then it would make sense to
accept the aircraft as soon as possible.


BTW, Boeing has been test flying ZA005 since Febriary 9th.
http://787updates.newairplane.com/787-Flight-Testing#


> http://787updates.newairplane.com/787-Electrical-Systems/Batteries-and-Advanced-Airplanes#gallery/2163221586001

That page also has a few videos.

There is a "contactor" before the metal bars leave the battery box. This
allows the logic board to disconnect the battery from the rest of the
plane. So the logic board in the battery box does provide the protection
against over or undervoltage, and according to the boeing guy, this
happen if any of the cells in the battery box go outside of valid range.
So it does appear that the battery pack has proper protections circuits.
However, the protection is applied at the exit from the battery box of
the conbined power, as opposed to individual shut off of a failed cell.

If the contactor circuit prevents charging after voltage dropped below
threshold, it would explain why the unit needs to be serviced since you
can't feed power to bring voltage back to acceptable levels. However,
the real problem is why the plane would allow batteries to deplete to a
level where the contactor trips. Plane should shutdown its systems
before allowing the battery safety to trip and permanently put batteries
out of service.


Comparison of 777 and 787 cells:

777: NiCd, 24 volts, 48.5kg, 16 amps for power up.
787: LiIon: 32 volts, 28.6kg, 150amps for start up.

So there is a huge difference with ability to provide huge current.

Also of importance: batteries are also a backup for brakes. In a
rejected takeoff scenario where all engines have failed, it is the
batteries that provide power to the electric brakes. (same as when plane
is being towed with engines off).


BTW, on the 30 minute video, it is stated that eliminating high pressure
bleed system saves about 2% of fuel.

787 has about 112km if wiring, while the less electric 767-300 has 144km
of wiring. Savings achieved with distributed power distribution
controllers instead of having all logic for power under cockpit in
previous aircraft.

APU battery can provide backup battery in flight. So if both main and
APU batteries can contribute

> Much more interesting: How will the 787-9 developement continue.

This has puzled me. Since the 787 was first delivered, Boeing has been
mum on the 787-9. It is as if someone declared "mission accomplished"
and Boeing stopped informing the press on the progress of the 787. Since
the 787-9 is the more popular model, it is susprising there Boeing
hasn't provide more updates on that project.
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JF Mezei
2013-02-27 07:32:10 UTC
Permalink
BTW, in the 30 inute Video, the Boeing guy did state that the APU shuts
off if the APU battery fails.

Does anyone have an explanation for this ? Seems sounter intuitive
since once you have APU running, if your batteries have failed, you want
the APU to keep on running.


Earlier he did mention that to start the APU up, the battery not only
powers the electric motor (aka reverse generator) to spin up the APU as
well the as the fuel pumps etc, but also energises the generator's
coils/magnets (not sure if stator or rotor).

Obviously, to get the generator going, the battery would need to
energise the coils. But once the generators (there are 2 on APU) are
going, would the coils remain powered by the battery, or would they be
powered locally by the generated power ?
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Uwe Klein
2013-02-27 09:24:23 UTC
Permalink
JF Mezei wrote:
> On 13-02-26 09:10, Uwe Klein wrote:
>
>
>>LOT has extended their 767 lease on Boeings urging till October.
>
>
> But this *could* be due to LOT agreeing to shift delivery slots to a
> later time so that Boeing could deliver on-time to some other airline.
>
> Unless you're a fly one the wall at the meeting where Boeing explains to
> the LOT president what is really happening, there is no way to know for
> sure.
LOT is bleeding.
Thus it is possible that they will like money more than efficient planes.
( See also Qantas recently publishing results improved by compensation from Boeing )


> The temporary fix may allow 78s7 back in the air, but how much downtime
> will be required when a permanent fix arrives many months down the road ?

Boeing says it is final fix. ;-)

> Is there a point in accepting 787s now if months down the road, they
> have to be off-line for a few weeks while their electrical systems is
> reworked ? If the planned permanent changes can be done overnight with
> battery swaps and control system swaps, then it would make sense to
> accept the aircraft as soon as possible.
>
> BTW, Boeing has been test flying ZA005 since Febriary 9th.
> http://787updates.newairplane.com/787-Flight-Testing#

They still need to find what strange effects kill the batteries.

>>http://787updates.newairplane.com/787-Electrical-Systems/Batteries-and-Advanced-Airplanes#gallery/2163221586001
mostly fluff.
Though the battery renderings replicated exactly my minds image from
what information was previously released.
A NiCd battery box with screw on top indicating "no maintainance".
( the NICd batts have quick release : maintainance : check/fill electrolyte levels )
i.e. they took an arrangement for vented nonexpanding cells
and copied the physical arrangement of cells over to Li-Ion
hermetic and potentially expanding cells. dumb!
>
>
> That page also has a few videos.
Haven't seen those. balks on my flash player ( right version, wrongly detected wrong )
>
> There is a "contactor" before the metal bars leave the battery box. This
> allows the logic board to disconnect the battery from the rest of the
> plane. So the logic board in the battery box does provide the protection
> against over or undervoltage, and according to the boeing guy, this
> happen if any of the cells in the battery box go outside of valid range.
> So it does appear that the battery pack has proper protections circuits.
That contactor will have significant issues shedding a high ( inductive )
load either in or out. You will get arcing on that contact.

> However, the protection is applied at the exit from the battery box of
> the conbined power, as opposed to individual shut off of a failed cell.
The battery is dead with a failed cell. no recourse.
But there was ony one temp sensor.
Thus chances were high that only chained failures would be detected.
There is a difference between all cells going or only one.
>
> If the contactor circuit prevents charging after voltage dropped below
> threshold, it would explain why the unit needs to be serviced since you
> can't feed power to bring voltage back to acceptable levels.
Savety lockout.

> However,
> the real problem is why the plane would allow batteries to deplete to a
> level where the contactor trips. Plane should shutdown its systems
> before allowing the battery safety to trip and permanently put batteries
> out of service.
Yes and/or start an attention grabbing alarm early during depletion.
>
>
> Comparison of 777 and 787 cells:
>
> 777: NiCd, 24 volts, 48.5kg, 16 amps for power up.
prob. 4..5h endurange
> 787: LiIon: 32 volts, 28.6kg, 150amps for start up.
less than 30min endurance. no wonder customers run the battery down
in this mode.

The voltages are a missrepresentation.
For NiCd 1.2V/cell is given that is the nominal cell voltage. max ~1.35V
For LiIon 4.0V/cell is given that is the absolute maximum allowable ( 3.7V is nominal )

Boeing is fibbing and missleading on every occasion. Why!?

>
> So there is a huge difference with ability to provide huge current.
Current requirements for APU start are similar.
777 just has less loads in start up.
Think carefully about what Boeing really tells you.
>
> Also of importance: batteries are also a backup for brakes. In a
> rejected takeoff scenario where all engines have failed, it is the
> batteries that provide power to the electric brakes. (same as when plane
> is being towed with engines off).
yes.

> BTW, on the 30 minute video, it is stated that eliminating high pressure
> bleed system saves about 2% of fuel.
I would contest that. ( viewing from a systemic approach. )
tsfc for the GEnx-2B is worse as it has less propulsive efficiency than
that larger fan -1B version.
>
> 787 has about 112km if wiring, while the less electric 767-300 has 144km
> of wiring.
All these "improvements" are really only true in relation to the 767.
But the 767 is on the techlevel of the first _A300_ . 40 years old.
But Airbus has a range of continuous advancements in their frames
from A310 (the 748 forex repliacates the limited FBW of A310 ), A320,
A340/330 to A380. Remote power switching is not new there.

To sum it up: There is not much on the 787 that you could not by
in Airbus craft before.( well, no electric aircon and antiice.)
>
>>Much more interesting: How will the 787-9 developement continue.
>
> This has puzled me. Since the 787 was first delivered, Boeing has been
> mum on the 787-9. It is as if someone declared "mission accomplished"
> and Boeing stopped informing the press on the progress of the 787. Since
> the 787-9 is the more popular model, it is susprising there Boeing
> hasn't provide more updates on that project.
There are regular "on time, on spec or better" PR releases.

But nothing tangible.
We will have to wait for First Flight as an unfakable event.

uwe
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JF Mezei
2013-02-27 19:49:26 UTC
Permalink
On 13-02-27 04:24, Uwe Klein wrote:

> LOT is bleeding.
> Thus it is possible that they will like money more than efficient planes.
> ( See also Qantas recently publishing results improved by compensation from Boeing )

And for Boeing, it allows it to use LOT's slots to deliver airplanes to
an airline would would be otherwise very angry at more delays. So it is
a win win situation.

> Boeing says it is final fix. ;-)

Out of curiosity, how come refueling other airplanes doesn't result in
their batteries being depleted because crews forget to turn off the
battery after they are done ?

or does this happen just as often except in those cases, it is just a
case of plugging in external power to start the airplane and the NiCd
batteries just get recharged ?

The solution would be to add some timer to deal with situations where
someone forgets to trun the lights off and the plane remains idle
without anyone in it, preventing batteries from being depleted.

Another change that needs to happen is for the battery box to first cut
off power before there is any damage to any cells, and allow inbound
power while outbound is blocked. This will allow the battery pack to be
safely recharged by the airplane and become usable once recharged
sufficiently.

If power is cut when voltage drops below the critical level, it means
that one or more cells are potentially damaged. But if you cut off power
before power drops to critical level, then you can safely recharge the
battery.

> They still need to find what strange effects kill the batteries.

The problem is that ZA005 isn't being used in a commercial setting at
some airport with normal airport workers. When you have "parents" taking
care of the problem child, they make sure to take good care of it. But
when the plane is at some commercial airport with contractors doing
refueliung, tugging etc, they are the ones which may end up triggering
conditions that the batteries don't like.


> i.e. they took an arrangement for vented nonexpanding cells
> and copied the physical arrangement of cells over to Li-Ion
> hermetic and potentially expanding cells. dumb!

I thought the Boeing Lithium Ion were not sealed and had vents ?


> But there was ony one temp sensor.

Boeing has indicated this will change.


> Yes and/or start an attention grabbing alarm early during depletion.

In fact, in the cockpit, in case of an emergency where engines are out,
the pilots need to know if/when batteries are about to fail. I suspect
the RAT doesn't produce enough power for braking when landing. So if
batteries are nearly out, pilots would need to know to warn crews and
passengers that the plane will likely not be able to stop before end of
runway.


Consider the Air Transat glider over the Atlantic, they ended up landing
hard/fast, and without thrust reversers, I suspect the wheel brakes
would be the big ticket item to get the plane to stop.

Running out of fuel isn't something that is far fetched. It has
happened. It will happen.




>> 787: LiIon: 32 volts, 28.6kg, 150amps for start up.
> less than 30min endurance. no wonder customers run the battery down
> in this mode.

How can you draw the conclusion it only has 30 minute endurance ?

Surely in an engine out "glider" situation, the batteries would not be
powering galleys and IFE systems.


>> So there is a huge difference with ability to provide huge current.
> Current requirements for APU start are similar.

I guess Boeing may state that LiIon can give 150amps, but they would
need to specify how many amps are needed for APU start, and more
importantly to brake aircraft without any engines.

It is interesting that if they used regenerative braking, it would help
power the aircraft at landing instead of drawing huge amounts from
batteries.

(and be able to brake with less heat generated at the wheel).

> 777 just has less loads in start up.

When the plane is dark, wouldn't startup being roughly the same. A few
lights, and turn on cockpit ?

Since Airbus appears to be able to easily switch the 350 to the NiCd
batteries, it would appear that APU start doesn't need 150amps of power.

When a conventional plane is being towed, what systems are needed ? APU
to run hydraulics for steering and braking ?

I take it the 787 could be towed on battery power with batteries running
hydraulics ?


>> BTW, on the 30 minute video, it is stated that eliminating high pressure
>> bleed system saves about 2% of fuel.
> I would contest that. ( viewing from a systemic approach. )
> tsfc for the GEnx-2B is worse as it has less propulsive efficiency than
> that larger fan -1B version.

A fair comparison would be 2 engines of the same size, one with bleed
air and the other with bigger generators.

I think one of the big advantages with electric is that when you don't
need de-icing, the electrical load is far less so the generators take
less power from engines.

Do bleed air system have ability to vary amount of air allowed to escape
from the compressor ? If de-icing is not needed at cruise, can they
reduce bleed air and thus increase engine efficiency ?

> All these "improvements" are really only true in relation to the 767.

Since the 767-300ER dates from late 1980s, could its wiring system
differ significantly from the original 767 with distributed power
controlers to reduce amount of wiring etc, or would the "type
certification" prevent such a big change in wiring philosophy ?

What about the 747-800. Would its wiring be totally different from that
of the original 747 ?


> To sum it up: There is not much on the 787 that you could not by
> in Airbus craft before.( well, no electric aircon and antiice.)

How does the 777 compare to the 787 in terms of wiring architecture ?
Does it also have distributed power with reduced wiring requirememnts,
or did Boeing still use more conventional power distribution on the 777 ?


> There are regular "on time, on spec or better" PR releases.

Does "on time" mean anything for the 787 programme ?

> We will have to wait for First Flight as an unfakable event.

Has Boeing begun to assemble the first -900 ? Are there bets who which
will be delivered for commercial use first the 787-900 or the A350 ?

And it isn't just a question of first flight and certification, but also
of how/whether Boeing can ramp up production. At current rates, by the
time Boeing will be done delivering launch orders, the aircraft will be
senile already !
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Uwe Klein
2013-02-27 21:33:24 UTC
Permalink
JF Mezei wrote:
> On 13-02-27 04:24, Uwe Klein wrote:

> Out of curiosity, how come refueling other airplanes doesn't result in
> their batteries being depleted because crews forget to turn off the
> battery after they are done ?
They don't start a bunch of powerhungry computers whenever some
access panel is opened.

>
>>They still need to find what strange effects kill the batteries.
>
>
> The problem is that ZA005 isn't being used in a commercial setting at
> some airport with normal airport workers.

There has been talk that sweaty passengers could well be
the deciding incredient. The Laredo incident was connected to
rain in the plane. condensation can be seen as FOD.

>
>>i.e. they took an arrangement for vented nonexpanding cells
>>and copied the physical arrangement of cells over to Li-Ion
>>hermetic and potentially expanding cells. dumb!
>
>
> I thought the Boeing Lithium Ion were not sealed and had vents ?

no the LVP65 Yuasa cells are prismatic 3.7V 65Ah nominal sealed Li-Ion
cells. The cells have burstplate in the upper third of the small sides.
Burst pressure should be around 650psi.

> Consider the Air Transat glider over the Atlantic, they ended up landing
> hard/fast, and without thrust reversers, I suspect the wheel brakes
> would be the big ticket item to get the plane to stop.
Yes. below speeds that allow power from the RAT the battery has
to power the brakes.
>
> Running out of fuel isn't something that is far fetched. It has
> happened. It will happen.
yup ;-)

>
>
>
>
>
>>>787: LiIon: 32 volts, 28.6kg, 150amps for start up.
>>
>>less than 30min endurance. no wonder customers run the battery down
>>in this mode.
>
>
> How can you draw the conclusion it only has 30 minute endurance ?
65Ah nominal will give you 30min @ 130A power draw ( actually a bit less )
>
> Surely in an engine out "glider" situation, the batteries would not be
> powering galleys and IFE systems.

they never do that. Theoretically the load on the batteries shouldn't
be all that much different from an 380 or A350.

But there is some kind of hitch hidden in that plane that Boeing has not divulged yet.
>
>
>
>>>So there is a huge difference with ability to provide huge current.
>>
>>Current requirements for APU start are similar.
>
>
> I guess Boeing may state that LiIon can give 150amps, but they would
> need to specify how many amps are needed for APU start, and more
> importantly to brake aircraft without any engines.

I've done some well educated guessing.
APU start is 5..8 kW for 50seconds or a max of ~240A current draw
taking ~15% of battery charge for one start cycle.
incidentaly: Main engine start (GEnx-1B) takes 350kW max / 200kW average ;-)
>
> It is interesting that if they used regenerative braking, it would help
> power the aircraft at landing instead of drawing huge amounts from
> batteries.
purely friction braking.
>
> (and be able to brake with less heat generated at the wheel).
>
>
>>777 just has less loads in start up.
>
>
> When the plane is dark, wouldn't startup being roughly the same. A few
> lights, and turn on cockpit ?
Going by Boeings word : NO.
>
> Since Airbus appears to be able to easily switch the 350 to the NiCd
> batteries, it would appear that APU start doesn't need 150amps of power.

It does.
Boeing seems to use intrisic Li-Ion properties in some unconventional
( actually abusive ) way.
>
> When a conventional plane is being towed, what systems are needed ? APU
> to run hydraulics for steering and braking ?
a towed plane is passive. only lights.
>
> I take it the 787 could be towed on battery power with batteries running
> hydraulics ?
battery running nav lights. ( and always a bunch of computers.)
>
>
>
>>>BTW, on the 30 minute video, it is stated that eliminating high pressure
>>>bleed system saves about 2% of fuel.
>>
>>I would contest that. ( viewing from a systemic approach. )
>>tsfc for the GEnx-2B is worse as it has less propulsive efficiency than
>>that larger fan -1B version.
>
>
> A fair comparison would be 2 engines of the same size, one with bleed
> air and the other with bigger generators.
>
> I think one of the big advantages with electric is that when you don't
> need de-icing, the electrical load is far less so the generators take
> less power from engines.
When you don't use much bleed you get full efficiency of the engine ;-)

>
> Do bleed air system have ability to vary amount of air allowed to escape
> from the compressor ?
sure

> If de-icing is not needed at cruise, can they
> reduce bleed air and thus increase engine efficiency ?
yes

>
>
>>All these "improvements" are really only true in relation to the 767.
>
>
> Since the 767-300ER dates from late 1980s, could its wiring system
> differ significantly from the original 767 with distributed power
> controlers to reduce amount of wiring etc, or would the "type
> certification" prevent such a big change in wiring philosophy ?

I don't thinks so. Boeing seems to have been rather conservative in that respect.

>
> What about the 747-800. Would its wiring be totally different from that
> of the original 747 ?
I don't think so. ( though it has the partial FBW from the A310 ;-)
It is a grandfathered cert.

After recent information gave some insight into FAA <> Boeing relationship
in respect to how certification is achieved ( self cert with FAA rubberstamping )
I understood how the grandfathering for the 737 and 747 was achieved.

EASA with a similar undertaking would have balked to no end.
And Boeing appears to be regularly unable to best Airbus under
the same certification requirements. i.e. only with newest tech
and the leeway older certification requirements provide is Boeing
able to be competitive.

>
>
>
>>To sum it up: There is not much on the 787 that you could not by
>>in Airbus craft before.( well, no electric aircon and antiice.)
>
>
> How does the 777 compare to the 787 in terms of wiring architecture ?
> Does it also have distributed power with reduced wiring requirememnts,
> or did Boeing still use more conventional power distribution on the 777 ?
>

The 777 has the cockpit section from the 767 while the rest could be seen
as a scaled 757. ( only partly joking )
The cockpit stuffing is said to be significantly different.
But I have no information about remote power control on the 777.
>
>
>>There are regular "on time, on spec or better" PR releases.
>
>
> Does "on time" mean anything for the 787 programme ?
;-)
>
>
>>We will have to wait for First Flight as an unfakable event.
>
>
> Has Boeing begun to assemble the first -900 ?
Part are said to be piling up.
> Are there bets who which
> will be delivered for commercial use first the 787-900 or the A350 ?
Haven't heard of any.
A350 seems to make good and securely achieved progress.
Airbus is contemplating to expand production beyond 10/month in 2019.
floated 180frames/a . Potential decission this summer.

Fixing problems early is the way to go. See "The Mythical Man Month",
IT related but a very good read. ( anything is IT related today ;-)

>
> And it isn't just a question of first flight and certification, but also
> of how/whether Boeing can ramp up production. At current rates, by the
> time Boeing will be done delivering launch orders, the aircraft will be
> senile already !
Some 787-8 frames will be 5..7 years old when delivered ( if ever )

I expect the 787 Mk2 to fare significantly better.
( Old english saying : never buy a Mk1 )

uwe
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JF Mezei
2013-03-02 21:53:10 UTC
Permalink
last Wednesday, Boeing reconfirmed that its proposed fixes for batteries
were a long term fix, not an interim fix.


I couldn't find the exact text for this, but I could see how this could
be true. The battery box fixes may be long term with no more changes
needed IF there are changes downstream in the power software/logic to
prevent those batteries from ever being drained to a point where damage
occurs.

In other words, the "permanent" contactor disconnect will no longer be a
pain for airlines requiring battery box replacement if the software
outside of the box no longer allows power draw to a point where the
"fuse of last resort" is tasked to save batteries.

It wasn't so much the news of a battery fire which were damaging, but
the combination of the battery fire with the number of batteries needing
to be replaced in the short life of the 787.

Seems to me like airlines will be asking Boeing to fix that problem too.
But that problem may remain under the carpet so that the FAA can give
green light for 787 to go back in the air, giving Boeing more time to
find a long term solution to the software.
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Uwe Klein
2013-03-03 12:53:50 UTC
Permalink
JF Mezei wrote:

> Seems to me like airlines will be asking Boeing to fix that problem too.
> But that problem may remain under the carpet so that the FAA can give
> green light for 787 to go back in the air, giving Boeing more time to
> find a long term solution to the software.

No idea about FAA but all other authorities will
require mandatory reporting on battery exchanges.
They also may show more scrutiny on other "preventive"
maintainance items that exchange parts long before their
expected service life expiration.

Wonder who kept the lid on those battery changes being reported.
IMHO below expectations service life is noteworthy in any case.

apropos elsewhere a link to an article
setting the grounding AD ( versus the in previous cases mandatory
certification retraction ) in perspective:
http://www.ainonline.com/aviation-news/blogs/ain-blog-torqued-emergency-ad-inappropriate-case-boeing-787

uwe
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JF Mezei
2013-03-09 06:58:43 UTC
Permalink
The NTSB has issued its interim report on the battery issue:

> http://www.ntsb.gov/investigations/2013/boeing_787/interim_report_B787_3-7-13.pdf

Some snippets:

The FDR data also showed that, about 36 seconds before the APU shut down
at 1021:37, the voltage of the APU battery began fluctuating, dropping
from a full charge of 32 volts to 28 volts about 7 seconds before the
shutdown.

Later, it mentions that viltage dropped 1 volt per second from 32 down
to 28, and then there were variations between 0 and 28 volts).

The APU battery provides power to start an APU during ground and flight
operations. The APU controller (discussed in section 1.6.5) monitors the
parameters that are needed to operate the APU. The APU controller is
powered by the APU battery bus, which receives its power from the APU
battery. If the APU battery fails, then the APU battery bus will no
longer receive power, and the APU will shut down.

(Note: I feel this is a design error, once the APU is running, it should
be able to continue without the APU battery. When you want redundant
sources of power, each source should not be disabled by failure of
another source)

Operational voltage range (volts)
20 to 32.2

So, the battery would have shutdown at 28 volts when the lower limit
would be 20. (or perhaps it rapidly degraded from 28 down to 20 between
samplings recorded on the FDR)


Another tidbit:
Boeing’s 787-8 electrical power system safety assessment also included
an analysis of lithium-ion battery cell failure modes. This analysis
determined that overcharging was the only known failure mode that could
result in cell venting with fire.

Will be interesting to see if thet discover other modes which cause
batteries to unravel.


Another design problem found: ventilation system was designed to react
in case of smoke to change valves and push smoke out of the plane
instead if circulate it to the cabin. However, because the APU shutdown
due to battery failure, there was no ventilation because power was off.
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Uwe Klein
2013-03-09 10:03:51 UTC
Permalink
JF Mezei wrote:
> The NTSB has issued its interim report on the battery issue:
>
>
>>http://www.ntsb.gov/investigations/2013/boeing_787/interim_report_B787_3-7-13.pdf
>
>
> Some snippets:
>
> The FDR data also showed that, about 36 seconds before the APU shut down
> at 1021:37, the voltage of the APU battery began fluctuating, dropping
> from a full charge of 32 volts to 28 volts about 7 seconds before the
> shutdown.

>
> Later, it mentions that voltage dropped 1 volt per second from 32 down
> to 28, and then there were variations between 0 and 28 volts).

Cell #5 shew arcing from cell body to battery enclosure.
Current flowing into the ( grounded but not used as a conductor ) enclosure
seems to have returned via the J1 wires and stainless steel mesh cladding
to the charger unit.( and not via the (burned off) grounding strap as in Japan.)
>
> The APU battery provides power to start an APU during ground and flight
> operations. The APU controller (discussed in section 1.6.5) monitors the
> parameters that are needed to operate the APU. The APU controller is
> powered by the APU battery bus, which receives its power from the APU
> battery. If the APU battery fails, then the APU battery bus will no
> longer receive power, and the APU will shut down.
>
> (Note: I feel this is a design error, once the APU is running, it should
> be able to continue without the APU battery. When you want redundant
> sources of power, each source should not be disabled by failure of
> another source)
there are pros and cons on that imho.
>
> Operational voltage range (volts)
> 20 to 32.2 ( 32.2 is mVs away from death imho )
>
> So, the battery would have shutdown at 28 volts when the lower limit
> would be 20. (or perhaps it rapidly degraded from 28 down to 20 between
> samplings recorded on the FDR)
>
>
> Another tidbit:
> Boeing’s 787-8 electrical power system safety assessment also included
> an analysis of lithium-ion battery cell failure modes. This analysis
> determined that overcharging was the only known failure mode that could
> result in cell venting with fire.

This is probably true.
( overvoltage and breach of passivation layer being the actual culprit )

And in both cases thermal runaway happened after about the same
time elapsed from using the battery for APU activity.
i.e. the charging cycle could well have reached similar states.

the Securaplane patented blind charge approach would overcharge
a single cell in the battery
if this cell has been damaged in previous use. ( reduced capacity,
same (over)voltage level after less charge )

note:
overcharge/overvoltage is the trigger for thermal runaway
and thus exposure of previously inflicted damage.
A regular charge cycle will invariably overcharge if there
is unexpected cell damage / capacity reduction.

i.e. resultant overcharge is potentially only an idicator flag.

>
> Will be interesting to see if thet discover other modes which cause
> batteries to unravel.
nailing the cell was an unsuitable test case. You have breached the
casing already.
>
>
> Another design problem found: ventilation system was designed to react
> in case of smoke to change valves and push smoke out of the plane
> instead if circulate it to the cabin. However, because the APU shutdown
> due to battery failure, there was no ventilation because power was off.

Yeah, cascading failures. Not realy unsurprising going on previous issues.
A filled shopping cart sold as a finished product.

uwe
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JF Mezei
2013-03-12 22:44:30 UTC
Permalink
http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14394

March 12, 2013
Contact: Laura J. Brown
Phone: (202) 267-3455

WASHINGTON, D.C. – The Federal Aviation Administration (FAA) today
approved the Boeing Commercial Airplane Company's certification plan for
the redesigned 787 battery system, after thoroughly reviewing Boeing’s
proposed modifications and the company’s plan to demonstrate that the
system will meet FAA requirements. The certification plan is the first
step in the process to evaluate the 787’s return to flight and requires
Boeing to conduct extensive testing and analysis to demonstrate
compliance with the applicable safety regulations and special conditions.
...
The battery system improvements include a redesign of the internal
battery components to minimize initiation of a short circuit within the
battery, better insulation of the cells and the addition of a new
containment and venting system.
...


So, 2 Boeing aircraft are OKed to fly in order to certify the safety of
batteries. What is notable here is that the changes include "redesign
of the internal battery components to minimize initiation of a short
circuit within the battery" something I had not seen mentioned before.
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JF Mezei
2013-03-15 16:13:12 UTC
Permalink
Boeing now expects the 787 fleet to be back in the air in "weeks"
according to a BBC article.



Also, Boeing is to include a "vent" so that smoke/fire will be vented
outside in case of battery problem. How is this done ? I assume some
sort of metal pipe running from battery to the outer skin ? How big
would such a pipe be in diametre ? Flexible or hard pipe ? Would this
mean that in case of fire, firemen will have more difficulty removing
the battery from the plane ?

And would this mean that during flight, the inside of the battery
compartment would be at outside air pressure at all times ?
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Uwe Klein
2013-03-15 17:23:23 UTC
Permalink
JF Mezei wrote:
> Boeing now expects the 787 fleet to be back in the air in "weeks"
> according to a BBC article.
>
>
>
> Also, Boeing is to include a "vent" so that smoke/fire will be vented
> outside in case of battery problem. How is this done ? I assume some
> sort of metal pipe running from battery to the outer skin ? How big
> would such a pipe be in diametre ? Flexible or hard pipe ? Would this
> mean that in case of fire, firemen will have more difficulty removing
> the battery from the plane ?

see:
http://www.boeingblogs.com/randy/archives/2013/03/sharing_our_solution_1.html

I will refrain from commenting on this heap of misdirection and spin.

uwe
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JF Mezei
2013-03-15 21:31:04 UTC
Permalink
On 13-03-15 13:23, Uwe Klein wrote:

> http://www.boeingblogs.com/randy/archives/2013/03/sharing_our_solution_1.html

##
An electrical insulator is being wrapped around each battery cell to
electrically isolate cells from each other and from the battery case,
even in the event of a failure.
##

Is it possible that if one cell spewed its guts out from the top, that
the liquid would then "short" terminals of other cells causing them to
also overheat ?

Or is the spewed liquid when a cell bursts considered not sufficiently
conductive to cause that ?

I'll watch the video later.
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JF Mezei
2013-03-16 02:24:58 UTC
Permalink
1 megawatt of power can be generated with 4 generators on 2 engines. But
787 can run on only 250kilowatts.

"Only job of batteries during flight is to keep the cockpit displays
from blinking when power is transitioned from engines to RAT".

Main (cockpit_ batteries provide braking while plane is towed on ground.
(brakes are electric). Also provides refueling and naginating lights
when being towed.

APU batteries apparently only provides APU start capabilities. (no
mention that this battery is required for APU to run once started).

Both at Takamatsu and Logon, 1 cell vented. The heat from the this
caused other cells to vent too.

vaprorized electrolyte looks like smoke but is not the result of combustion.

Boeing says there was no fire inside the blue box in either accident.
(The inside of the blue box for the Logan even seems to indicate some
form of combustion in my opinion, but Boeing says it depends on the
perspective of the observer :-)

Vented electrolyte at Takamatsu event was treated as smoke by smoke
detectors and active ventilation did push this "smoke" out instead of
speading it to cabin.


Neither Logan not Takamatsu events put the aircraft in jeoperdy.

Batteries were properly charged, not overchanged in both events.
Boeing very confident overcharging ever happened.

Boeing says that the enclosure will ELIMINATE possibility of a fire.
Repeats many times that fire is impossible within the enclosure.

Enclosure has a burst disk between itself and the tube to overboard.
This begs the question about how much pressure must be present before
burst disk burts on ground versus at altitude.


Priority will be to repair already delivered planes first before
resuming deliveries.

At the very end, some piece of real information:

Modificarions add 150lbs (about 70kg) to each airplane, negating the
weight and space savkngs offered by lithium-ion batteries but those
batteried stl provide advantages on ground for large amount of power
delivery.
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Uwe Klein
2013-03-16 08:59:00 UTC
Permalink
JF Mezei wrote:
Good Morning.

> 1 megawatt of power can be generated with 4 generators on 2 engines. But
> 787 can run on only 250kilowatts.
deice 75kW min ( found a thesis that worked the requirements.
more like 100+kW for regular use )
cabin air conditioning 100kW at cruise FL 100+kW ( educated guess )

>
> "Only job of batteries during flight is to keep the cockpit displays
> from blinking when power is transitioned from engines to RAT".
My feeling is that this is a semantic fib ( just like the no fire nomenclature ).
>
> Main (cockpit_ batteries provide braking while plane is towed on ground.
> (brakes are electric). Also provides refueling and naginating lights
> when being towed.
65Ah and upto 140A current draw provide <30 minutes endurance on batteries alone.
Every door or external accesspanel opening will cause computers to start and a high
current draw,
customers having problems with run down batteries isn't really surprising at all.

>
> APU batteries apparently only provides APU start capabilities. (no
> mention that this battery is required for APU to run once started).
the NTSB report says APU goes down if battery lost.
>
> Both at Takamatsu and Logan, 1 cell vented. The heat from the this
> caused other cells to vent too.
Right, imho the vents should have a complementary opening in the enclosure
and a channel fitted there to the outside ..
>
> vaprorized electrolyte looks like smoke but is not the result of combustion.
electrolyte is lithium salts solved in an organic liquid.
heat it good and it "cokes" up --> gooey black residue.
>
> Boeing says there was no fire inside the blue box in either accident.
> (The inside of the blue box for the Logan even seems to indicate some
> form of combustion in my opinion, but Boeing says it depends on the
> perspective of the observer :-)
Waterboarding is not torture.
I did not have s* with that woman.
....

>
> Vented electrolyte at Takamatsu event was treated as smoke by smoke
> detectors and active ventilation did push this "smoke" out instead of
> speading it to cabin.
>
>
> Neither Logan not Takamatsu events put the aircraft in jeoperdy.
Probably true for the limited view on the vent only.
APU is required for ETOPS. Loosing the main battery every
22k hours is like the battery being nonexistent which
imho pulls the rug from any ETOPS capabilities.

>
> Batteries were properly charged, not overchanged in both events.
> Boeing very confident overcharging ever happened.
If you have damaged a single cell in an unnoticed undercharge situation
( if not a total failure this reduces capacity ) the patented charger
algorithm will invariable overcharge that single cell --> poof.
>
> Boeing says that the enclosure will ELIMINATE possibility of a fire.
> Repeats many times that fire is impossible within the enclosure.
Schrödingers cat. fire will only potentially instantiate when you
look inside the box for fire. as you can't look, there is no fire ;-)

The box looks like it could contain a full battery failure.
But the battery has purpose in the failure/backup concepts that
provide ETOPS capabilities. It may not be in regular use though.

IMHO this is a sophist lie.
>
> Enclosure has a burst disk between itself and the tube to overboard.
> This begs the question about how much pressure must be present before
> burst disk burts on ground versus at altitude.
couple hundred psi?
>
>
> Priority will be to repair already delivered planes first before
> resuming deliveries.
>
> At the very end, some piece of real information:
>
> Modificarions add 150lbs (about 70kg) to each airplane, negating the
> weight and space savkngs offered by lithium-ion batteries but those
> batteried stl provide advantages on ground for large amount of power
> delivery.
_The much, much, much more interesting tidbit was:_

* the charger has been moved into direct vicinity to the battery
( much shorter connections, common ground.point for reference )

* the charger has been set for lower final charge levels.

* the charger has been altered in how high and abrupt charge transients will be.

* The cutoff circuitry will be set to higher minimum levels.


uwe
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