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WSJ:
"It is not immediately clear whether ANA reported the replacement of its 787 batteries to Boeing, according to Mr. Nomura. The carrier didn't at the time tell Japanese authorities because the incidents didn't rise to the level of seriousness required for such reports, he said." Note the careful "not immediately' clear followed by "at the time". |
http://graphics8.nytimes.com/package...30-battery.png
Schematic of the battery in the New York Times. Image is too big to post, so go to the link. |
Seattle Times reports more than 100 (up to 150) dreamliner batteries have "failed" and were exchanged until now.
At least 100 batteries failed on 787 fleet | Business & Technology | The Seattle Times |
Well remarkably the unofficial lab test on Li-Mn went well. Shorted them, burnt them, then CO2 put them out, and they did not reignite. Have Boeing just gone on the cheap with Li-Co ?
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Expert States Battery Design is Unsafe
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This information signals a departure from best practice, and suggests the problem was covered up. Whether legally not reported is a different discussion, and debuts a suggestion that there may be a possibilty of violations of regulations, willfully.That could be an actual crime, depending on the circumstances.
One hundred unscheduled replacements could be just a cost of doing business, but with only fifty aircraft in service, the frequency averages to two per a/c. That is troubling... How does one "ferry" a fresh Lithium Battery? It defies logic that an aircraft would deadhead to the new part, and if it did, it couldn't carry pax....Can't fly a jet without backup electrical....Without permission from JTSB/FAA? |
Shame Flightglobal didn't check its facts first.
Apu battery by the aft cargo door? Don't think so. I'll take that article with a pinch of salt methinks. Bloody journos! |
Yes, the drawing shows the APUBAT on the wrong side of the a/c.
It is actually located on the right hand side of the EE Bay, facing aft. NTSB is limiting its investigation into one destroyed battery and one exemplar? One thinks they might consider the 100 or so that were changed out, and why they failed? Its in the a/c logs, ok? That's 6300 pounds of Lithium Batteries, unusable.......One imagines the NTSB might want to examine these defectives in situ, that's alot of electrolyte to put in the hold of a freighter. |
In five of the 10 replacements the main battery had showed an unexpectedly low charge Lithium Battery Failures Under-voltage / Over-discharge Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials. Anodes First the anode copper current collector is dissolved into the electrolyte. This increases the self discharge rate of the cell however, as the voltage is increased again above 2 volts, the copper ions which are dispersed throughout the electrolyte are precipitated as metallic copper wherever they happen to be, not necessarily back on the current collector foil. This is a dangerous situation which can ultimately cause a short circuit between the electrodes. |
An ongoing problem for Boeing?
But that's an issue at very low voltages. The protection circuits should & did disconnect the batteries before they got that low. The estimated number of replacement batteries is 100-150. Even taking the lower of those figures that is, as someone has already pointed out, more than two batteries per aircraft in just over a year in service. If these batteries were replaced by Boeing under warranty, then they have known that they have a problem with the battery/charging/monitoring system for some time. I would be very interested to know the timescale of these replacements. If they started in October 2011 and the number replaced is nearer the 150 mark then that is potentially as many as six or seven batteries replaced per aircraft! I would also be interested to know how the number of replacements break down between main and aft as they are identical units but are both connected to differing parts of the electrical system. This information would be a big aid to diagnosing the problem. What can be said for certain is the that the two battery events probably came as no surprise to Boeing and that they must have been working on a resolution to this problem for some time while throwing $130,000 worth of battery at each aircraft per year. :sad: |
Each Battery's replacement cost is 16k.
But at this point, money is WAY down the list regarding the install. The logistics of a problem of this magnitude can only be imagined. Each install could be considered an unscheduled "event", and it is a virtual certainty that FAA were notified. "Incident" comes to mind, X150...... There is no "discretion" it is a no go item.....without paperwork. |
Lyman
Only in the US.
The ANA source says that battery replacement was not a matter for the regulator and only Boeing were informed. |
As stated above "when the battery goes off with a bang it produces Oxygen."
I suggest that those claiming that thermal runaway in Li-ion batteries produce oxygen in the off gasses would document the source of that claim. "Lithium-Ion Batteries Hazard and Use Assessment" was published in July 2011 and was written by four professional and/or PhD engineers at Exponent Failure Analysis Associates, Inc. The report clearly states: "No significant amount of oxygen is found in cell vent gases…, but plays no measurable role in the flammability of vent gases." Details from the report on page 49: “ Exponent and others have measured cell case temperatures during thermal runaway reactions. For fully charged cells, these temperatures can reach in excess of 600°C (1,110°F); case temperatures for lithium-iron phosphate cells are generally lower. The temperature rise is driven by reactions of the electrodes with electrolyte and release of stored energy. Some cathode materials will decompose and may change their crystalline structure.This fact has led to a misconception that lithium-ion cells burn vigorously because they “produce their own oxygen.” This idea is incorrect. No significant amount of oxygen is found in cell vent gases.91 Any internal production of oxygen will affect cell internal reactivity,11 cell internal temperature, and cell case temperature, but plays no measurable role in the flammability of vent gases. A footnote on the same page states: “Analysis of cell headspace gases can reveal the presence of argon, nitrogen, and oxygen consistent with cell construction conditions. In one instance (testing of a prototype cell), trace quantities of oxygen and hydrogen were measured in cell vent gases, but spark ignition testing of those gases did not result in ignition.” Page 52 of the report also states: “Depending upon the environment around the cell, the cell vent gases may ignite. The gases are not “self-igniting.”27, 93 There must be sufficient oxygen in the surrounding environment to sustain combustion of hydrocarbons and there must be a competent ignition source to ignite the vent gases.” The report offers multiple tables and data points demonstrating off gas compositions concentrations , including no oxygen, and various options for inerting the the thermal runaway off gases. The report also describes various tests with cooling the thermal runaway. |
SoS
True, but Boeing is under the jurisdiction of the FAA, and compelled to report applicable and pertinent data as a principal party, and holder of the certificate. No reasonable interpretation of the laws around disclosure of material fact releases Boeing from the obligation to report......imo. They would have to represent that the failures were not reportable. Hmmm....... |
I suggest that those claiming that thermal runaway in Li-ion batteries produce oxygen in the off gasses would document the source of that claim. http://cdn.intechopen.com/pdfs/10407..._batteries.pdf Thermo-chemical process associated with lithium cobalt oxide cathode in lithium ion batteries snip Flow of current over and above the tolerable/standard charged state causes instability to the cathode which starts to release oxygen into the electrolyte. Thus released oxygen reacts exothermally with the lithium plated over the graphite anode and increases the temperature of the cell making the cathode to release oxygen further. The cell which was in the dormant state in the absence of oxygen and heat now becomes an explosive device in the event the cell is met with any abuse. |
Despite the incidents, McNerney said he didn't doubt the decision to use the new technology. "Nothing we've learned has told us yet that we have made the wrong choice on the battery technology," he said. "We feel good about the battery technology and its fit for the airplane. Boeing says it will find cause of 787 problems, defends batteries - latimes.com |
True, but Boeing is under the jurisdiction of the FAA, and compelled to report applicable and pertinent data as a principal party, and holder of the certificate. Is this a conversation that could have been taking place in private, between Boeing and the FAA? |
It is not necessarily as bad as it may seem. Boeing could have been reporting, and the FAA monitoring. It is a large discrepancy from the approved use, imo.
It is inconceivable that Boeing kept this to themselves, in hindsight. Dispatch rate is a commercial consideration, but failure rate is regulatory, and seems to me to be not negotiable. Does FAA have obligations to report? To whom? The Transportation Secretary, who just resigned? Ray LaHood? Both Boeing and Ray LaHood are from Chicago, Illinois. Boeing claims they are prevented from commenting, maybe the Transportation Secretary could comment? He had a statement after the grounding... Nothing about safety could or should be construed as "proprietary". imo. |
BOEING should have ask themselves:
"What's wrong with the batteries?" > 100, each 16.000 USD!!!!! |
1.6 Million USD plus labor, lost revenue, and angry clients.
But the CEO still has confidence in the batteries. A new paradigm? Pain is good? |
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