Boeing 787 toast

waynefromnscanada

Re: Boeing 787 toast

Not just Boeing having problems with lithium batteries.
" According to a government safety official with knowledge of the episode, the Cessna battery had drained below 5 percent of its charge. The problem with lithium batteries, however, is that recharging a battery that has been drained to a low point can create a risk of fire because the battery is unable to accept a charge. Recharging it then creates heat that can cause it to ignite.

(Which adds to my concern as a firefighter, about the ever increasing numbers of items, from cell phones to cordless tools that people are bringing into their homes and abusing. And many of these home-use batteries, I suspect, don't come with sophisticated battery monitoring circuitry like is found in the aviation industry.)

After discussions with the F.A.A., Cessna decided to replace the (Lithium) battery on its planes with nickel cadmium batteries"
http://www.nytimes.com/2013/01/30/business/boeing-aware-of-battery-ills-before-the-fires.html?pagewanted=2&_r=1&smid=fb-share

nsaspook

Re: Boeing 787 toast

Wow, over a hundred battery failures long before the fire and smoke events.
http://seattletimes.com/html/businesstechnology/2020241385_787deadbatteriesxml.html

Most of the batteries were returned because they had run down so far that a low-voltage cutout was activated.

At that stage, the batteries, which cost about $16,000 each, are essentially dead and cannot be recharged.

BB.

Re: Boeing 787 toast

Lithium batteries have always been a big "no no" in aircraft from times past (only very small cells in exit slides, emergency lighting, emergency locators, etc.). Too much energy is available if the larger battery fails or is damaged in some way.

I know the newer chemistries are supposed to much safer--But in the search for high density, high power, and small size/low weight--They appear to have gone with the "less safe" alternative and start adding engineering measures around these devices to protect against excursions outside the operating parameters.

In general, when you start adding more and more engineering stop gaps to make something "acceptably safe"--You are probably not (see space shuttles). Consensus engineering is about as useful as consensus science.

-Bill

nsaspook

Re: Boeing 787 toast

Controlling large Lithium batteries packs is like juggling glass balls filled with nitroglycerin:
http://www.youtube.com/watch?v=gwoErwyBST0

waynefromnscanada

Re: Boeing 787 toast

Update!
""This is a clear indication that Boeing has identified the problem and may even have found a solution," he said.
"The logical step is to conduct test flights and see if the solution does work."
http://www.bbc.co.uk/news/business-21332256

RCinFLA

Re: Boeing 787 toast

I have read a few contradicting reports. Still sounds like some political fingerpointing and counter fingerpointing going on. Japan ministry says the batteries are not the root cause (Japan sources the batteries). They seem to imply the charge controller / monitor (French built) is the root cause. ANA 787's have changed out a large number of batteries due to issues since they have been using 787's which should have been an early warning sign.

inetdog

Re: Boeing 787 toast

waynefromnscanada wrote: »

Update!
""This is a clear indication that Boeing has identified the problem and may even have found a solution," he said.
"The logical step is to conduct test flights and see if the solution does work."
http://www.bbc.co.uk/news/business-21332256

Sounds to me more like shots in the dark still: "Some analysts said that Boeing's request to start test flights may be a way for them to establish that the battery issues that impacted the JAL and ANA flights may have been unique to those two planes."

In other words, the problem is not with the battery or the electrical system around it, just some unspecified and undetermined thing which was different in these two planes. Obviously that explains why there have been no failures since. Oh, wait a minute....

waynefromnscanada

Re: Boeing 787 toast

"Asked for more details about the plans, Birtel declined to comment, but a series of test flights would allow the company's engineers to study the performance of the aircraft's lithium batteries in normal operating conditions."
http://money.cnn.com/2013/02/05/news/boeing-dreamliner-test-flight/index.html?hpt=hp_bn1

solar_dave

Re: Boeing 787 toast

RCinFLA wrote: »

I have read a few contradicting reports. Still sounds like some political fingerpointing and counter fingerpointing going on. Japan ministry says the batteries are not the root cause (Japan sources the batteries). They seem to imply the charge controller / monitor (French built) is the root cause. ANA 787's have changed out a large number of batteries due to issues since they have been using 787's which should have been an early warning sign.

I heard on CNBC that the French made battery cables were suspect.

ggunn

Re: Boeing 787 toast

solar_dave wrote: »

I heard on CNBC that the French made battery cables were suspect.

Freedom Cables!

techntrek

Re: Boeing 787 toast

ggunn wrote: »

Freedom Cables!

...which were French fried.

ggunn

Re: Boeing 787 toast

techntrek wrote: »

...which were French fried.

Making the Boeing 787 French toast?

nsaspook

Re: Boeing 787 toast

I still think the root problem is not in the electronics or caused by a manufacturing defect so even if they "fix" the problem they still need to have the Cessna solution, "total containment" to stop a runaway chemical process.

http://seattletimes.com/html/businesstechnology/2020241162_787battery29xml.html

BB.

Re: Boeing 787 toast

Yep--The nature of the beast... Even if every possible known failure mode has been addressed--There are a whole bunch of unknown failures in Murphy's tool box.

Total containment and/or "bombs away" are still going to be needed.

-Bill

RCinFLA

Re: Boeing 787 toast

The report today is the battery certification process and failure containment box did not consider that one bad cell could set off a chain reaction by direct heating other batteries, in turn setting them off. The containment box could not handle all the cells in thermal runaway.

inetdog

Re: Boeing 787 toast

RCinFLA wrote: »

The report today is the battery certification process and failure containment box did not consider that one bad cell could set off a chain reaction by direct heating other batteries, in turn setting them off. The containment box could not handle all the cells in thermal runaway.

This may have been made worse by the fact that apparently there was only one temperature sensor (rather than one per cell) in the BMS system. If that is confirmed, it is a really bad design decision. Not that it would have helped in this particular situation, but it might at least have given more warning.

Elon Musk, of Tesla Motors, called them out days ago for a design which did not provide thermal distance between the batteries to prevent just this type of failure.
Maybe the idea was that to prevent thermal runaway they wanted to try to keep all the batteries at the same temperature? :-(

inetdog

Re: Boeing 787 toast

RCinFLA wrote: »

The report today is the battery certification process and failure containment box did not consider that one bad cell could set off a chain reaction by direct heating other batteries, in turn setting them off. The containment box could not handle all the cells in thermal runaway.

Remind anyone of the mortgage crisis?

nsaspook

Re: Boeing 787 toast

There are some things that are almost impossible to control even if in theory we can build systems to use them safely. About 10 years ago at work we installed some systems that used Chlorine trifluoride CIF3 for cleaning a special process chamber. The stuff works like magic but we finally decided the danger of a leak (after a few alarms) exceeded any possible gains so we dismantled the entire system at great cost. Boeing has been lucky so far, I really hope they, the FAA and the NTSB do the right thing before letting the public fly this plane again.

waynefromnscanada

Re: Boeing 787 toast

This from The Aviation Herald, dated 7 Feb, 2013:
"On Feb 7th 2013 the NTSB reported: "After an exhaustive examination of the JAL lithium-ion battery, which was comprised of eight individual cells, investigators determined that the majority of evidence from the flight data recorder and both thermal and mechanical damage pointed to an initiating event in a single cell. That cell showed multiple signs of short circuiting, leading to a thermal runaway condition, which then cascaded to other cells. Charred battery components indicated that the temperature inside the battery case exceeded 500 degrees Fahrenheit." Mechanical impact damage as well as external short circuiting have been ruled out as causes, deformations and arcing were the result of a battery malfunction. The NTSB continued that Boeing conducted a risk assessment during the certification process which did not identify any possibility of a cell to cell propagation or of fire, both of which however occurred in the battery fire events at Boston. Boeing further assessed that a smoke release event would occur one time in 10 million flight hours, however, the two events at Boston and Takamatsu bring the balance to two events in 100,000 flight hours well above the failure rate predicted in the certification process. The NTSB concluded: "the possibility that a short circuit in a single cell could propagate to adjacent cells and result in smoke and fire must be reconsidered."

BB.

Re: Boeing 787 toast

Just a little change in temperature, and the risk of failure goes up by ~5-1,400x and you lose a space shuttle.

A difference in safety factor by 100-200:1 -- Does not impress me very much in a commercial airliner (If I understand the math correctly--and with statistics, I probably don't)...

-Bill

Title: Risk analysis of the space shuttle: pre-challenger prediction of failure
Author(s): Siddhartha R. Dalal , Edward B. Fowlkes and Bruce Hoadley
Source: Journal of the American Statistical Association. 84.408 (Dec. 1989): p945. From General OneFile.
Document Type: Report

Full Text: COPYRIGHT 1989 American Statistical Association http://www.amstat.org/

Abstract:
The Rogers Commission report on the space shuttle Challenger accident concluded that the accident was caused by a combustion gas leak through a joint in one of the booster rockets, which was sealed by a device called an O-ring. The commission further concluded that O-rings do not seal properly at low temperatures. In this article, data from the 23 preaccident launches of the space shuttle is used to predict O-ring performance under the Challenger launch conditions and relate it to the catastrophic failure of the shuttle. Analyses via binomial and binary logistic regression show that there is strong statistical evidence of a temperature effect on incidents of O-ring thermal distress. In addition, a probabilistic risk assessment at 31 [degrees]F, the temperature at which Challenger was launched, yields at least a 13% probability of catastrophic field-joint O-ring failure. Postponement to 60 [degrees]F would have reduced the probability to at least 2%. To assess uncertainty in estimates and for any future prediction under the Challenger scenario, a postanalysis prior distribution of the probability of a catastrophic failure is derived. The mean and median for this distribution for 31 [degrees]F are at least .16 and .13, and for 60 [degrees]F they are at least .004 and .02, respectively. The analysis of this article demonstrates that statistical science can play an important role in the space-shuttle risk-management process.


KEY WORDS: Catastrophic failure; Data analysis; O-rings; Probability risk assessment; Statistical science.

waynefromnscanada

Re: Boeing 787 toast

“There are some changes to the systems that I know they are going to introduce, but I can’t disclose too much of it because I have been given information on a confidential basis,” Walsh, whose International Consolidated Airlines Group SA includes British Airways and Iberia, said yesterday in Dublin. “They will have to do some redesign of the battery system and I would expect it to take a couple of months, but I don’t have any detailed information to understand when they will address that.”

waynefromnscanada

Re: Boeing 787 toast

http://edition.cnn.com/video/?hpt=hp_tvbx#/video/business/2013/02/08/lklv-quest-dreamliner-timescale.cnn

RCinFLA

Re: Boeing 787 toast

LiIon battery safety is all about maintaining separator integrity. Separator thickness is in the range of 15-25 um.

LiIon has trouble handling overcharging energy. Much of the overcharge energy generates heat. A lead acid battery dissipates much of the overcharge energy by 'cracking' water into hydrogen and oxygen leaving less to be dissipated as heat energy. When there is multi-cell battery pack made of a number of series connected cells just controlling the packs overall voltage and current during charging is not enough. This is why BMS systems are so complicated for LiIon batteries.

I assume these batteries are built with a multi-layer separator. The composition of the multilayer separator is to have one or more of the separator laminates made of a material with a lower transition temperature (temp at which material begins to melt to a soft gel). The purpose of this is to provide a separator shutdown function similar to self sealing gas tanks on military fighter aircraft. It is suppose to seal a breach caused by localized overheating.

Thermal runaway in LiIon battery is the result of massive failure of separator. There must be some basic problem with the separator design on these batteries. On large LiIon cells the thermal profile within the cell is much different then smaller AH cells and a separator design with a proven track record in, say laptop computers, becomes very inadequate for a larger cell design. Secondary, the design of the battery pack is not providing sufficient thermal isolation between the cells so one cell in thermal runaway does not overheat nearby cells.

I hope this thread enlightens folks about attempting to install LiIon batteries in their off-grid setup without a good BMS system.

waynefromnscanada

Re: Boeing 787 toast

Airbus ditches lithium-ion batteries from A350 after Dreamliner fiasco and reverts to conventional nickel-cadmium batteries

http://www.guardian.co.uk/business/2013/feb/15/airbus-lithium-ion-batteries-dreamliner

waynefromnscanada

Re: Boeing 787 toast

Published Feb 16.
"The initial redesign includes a fireproof battery box, made of titanium or steel, several sources said. That will seal the cells, keeping moisture out and flames in.
It also includes a venting system that will directly evacuate to the outside any vapor and liquid flowing from the battery.
In the two recent battery overheating incidents, flammable liquid and vapor sprayed out of the battery and across the electronics bay where the battery sits, before reaching an outflow valve.
Longer term, the battery box will be enlarged to provide more separation between the battery’s eight cells, several sources said.
That will help ensure that overheating of one cell doesn’t spread to others — a so-called “thermal runaway” that occurred in both recent incidents.
The battery control system will have sensors to monitor the temperature and voltage of each individual cell rather than the battery as a whole, one source said.
And the same source said engineers are also working on using an inert gas such as halon or nitrogen to expel the oxygen generated when a battery overheats."
http://seattletimes.com/html/businesstechnology/2020373450_boeing787xml.html?syndication=rss

Cariboocoot

Re: Boeing 787 toast

And they didn't think of that to begin with?

waynefromnscanada

Re: Boeing 787 toast

Cariboocoot wrote: »

And they didn't think of that to begin with?

Appears that way. However, from all I've been reading, this is the first plane by Boeing that they themselves didn't design from nose to tail. The Boeing "bean counters" stepped in and convinced the top brass it would be cheaper to farm out the different parts designs etc to various companies and countries around the world, trusting those unrelated companies to both understand what Boeing needed, and that they'd do it right. Many of the early delays appear to have been a direct result of this farming out and the left hand not knowing what the right was doing. After the fact, the Boeing bosses realize that listening to the bean counters, who understand beans but not aircraft design and engineering, has been a colossal mistake, not only costing them dearly, but threatening to put the company under unless they can get this thing turned around in a hurry.

waynefromnscanada

Re: Boeing 787 toast

Good News????????????
Boeing 787 Dreamliner's failed battery was wired incorrectly, Japan says!
Japan's transport safety board said in a report that the battery for the aircraft's auxiliary power unit was incorrectly connected to the main battery that overheated.
On Wednesday Air India became the latest airline to say Boeing had told it it is hopeful of getting the Dreamliner back in service soon.
http://www.guardian.co.uk/business/2013/feb/20/boeing-dreamliner-failed-battery-wired
Flickering of the plane's tail and wing lights after it landed and the fact the main battery was switched off led the investigators to conclude there was an abnormal current traveling from the auxiliary power unit due to miswiring. http://www.komonews.com/news/boeing/Investigators-say-battery-on-Boeing-787-was-wired-incorrectly-192027601.html

westbranch

Re: Boeing 787 toast

Makes one ask why they are connected in the first place. It's supposed to be a redundant system isn't it, if the other one failed??

Cariboocoot

Re: Boeing 787 toast

What have we always said about connecting dissimilar batteries? It's a no-no.