|
787 Batteries and Chargers - Part 2
Thread Part 1 starts here.
|
Just to get the continuation rolling, so people realize it is open....
Welcome to Part II.
Machaca: It is my understanding both transcripts and videos of all the sessions will be available next week on the NTSB website. Line 375: YOU WILL NOTICE IN MY PRESENTATION, WHEN YOU SEE IT ON THE DOCKET, THAT I HAVE INFORMATION FOR BOTH LIVE IN MY AUNT AND METAL BATTERIES. -- FOR BOTH LITHIUM AND METAL BATTERIES. There is also some good stuff, like this, which pretty well lays to rest all of the speculation about the effect of electrolyte combustion and the contribution of the oxygen liberated within the battery electrode (which is small enough to combust only a very small fraction of the electrolyte): WHICH THEN GOES BACK TO DR. CHIANG'S POINT. IF YOU ENGINEER A SYSTEM THAT HAS NO OTHER AVAILABLE OXYGEN, YOU TAKE AWAY THAT HEAT SOURCE, THAT ENERGY SOURCE, WHICH IS ROUGHLY, IN A GIVEN CELL, THE COMBUSTION ENERGY OF THE ELECTROLYTE IS 1 TO 2 TIMES THE ENERGY THAT IS CONTAINABLE IN THE CELL. IT IS NOT A SMALL AMOUNT. THOSE ARE MY TWO COMMENTS. Also, a very nice sequence on the choice of Li chemistry: (ITALIC text is my insertion.) Starting at 319: >> UNDERSTANDING THAT EVERYTHING THAT WE DO HAS SOME RISK IN IT, ARE THERE CERTAIN LITHIUM-ION CHEMISTRIES THAT HAVE BEEN DETERMINED TO BE UNSUITABLE FOR CERTAIN APPLICATIONS AS FAR AS RISK LEVEL? >> I DON'T THINK THAT QUESTION LEADS TO A PRODUCTIVE RESULT. TO BAN A CERTAIN TYPE OF THEM ASTRAY. -- TYPE OF CHEMISTRY. >> NOT NECESSARILY BANNING. CHOICES PEOPLE HAVE MADE FOR A CERTAIN ENVIRONMENT. FOR EXAMPLE, ON A SUBMARINE, ON AN AIRCRAFT CARRIER, OUT ON A SATELLITE, ARE THERE CERTAIN CHEMISTRIES THAT HAVE BEEN RULED OUT THE CAUSE OF THEIR RISK? >> WHEN WE WERE TESTING MODULES, WE WOULD IT MODULES WITH A " SAFER CHEMISTRY" AND ONES WITH A MORE DANGEROUS CHEMISTRY IN THE CELLS. THE PERFORMANCE OF THE MODULES DIDN'T FOLLOW. THE CELLS THAT WERE DEEMED SAFER AT THE MODULE LEVEL PERFORMED WORSE. SO I WOULD ADVISE A COMPREHENSIVE AND THOUGHTFUL TESTING PROGRAM AND NOT WORRY ABOUT WHAT THE CHEMISTRY OF THE CELL IS. >> I WOULD COMPLETELY AGREE. I THINK THE IMPORTANT REASON TO SAY THAT IS I CAN BUILD A COBALT, A HIGH CHARGED COBALT CELL INTO A MODEL THAT MAY NOT FAIL AND COULD WEIGH A TON. SO I CAN MAKE THAT BATTERY IN PHOSPHATE AND IT MIGHT WEIGH FIVE POUNDS. SO THE SAFETY REQUIREMENT OF THE APPLICATION, WE WILL HAVE TO GIVE YOU THE LIGHTEST, MOST COST-EFFECTIVE SOLUTION. BUT YOU, THE USER, CAN SAY I WILL NOT TOLERATE THIS. I CANNOT ACCEPT THAT. THIS IS A FAILURE. THE NAVY PROGRAM HAS DEVELOPED A VERY CLEAR YOU CANNOT PUT THIS ON OUR SUBMARINE IF IT DOES THESE THINGS. THAT WILL DRIVE US TO CHOOSE THE SYSTEM DESIGN, INCLUDING CHEMISTRY AND EVERYTHING, TO DELIVER WHAT THEY WANT. BUT TO DECIDE THAT A CHEMISTRY CANNOT WE USED IS LIKE TRYING TO SOLVE A PROBLEM WITH THE FIRST GRAIN OF SAND. >> WITH RESPECT TO APPLICATIONS, THE CHEMISTRY IS IMPORTANT IF YOU WANT A VERY HIGH RATE APPLICATION. WE WOULD CERTAINLY GO WITH LIKE A SPINNER (spinel?) OR A PHOSPHATE TYPE OF CHEMISTRY. IF YOU ARE NOT LOOKING FOR HYBRID (higher?) PERFORMANCE, THEN WE WOULD GO WITH [INDISCERNIBLE] SO I THINK WE WOULD GO WITH THAT MORE THAN THE SAFETY OF THE CHEMISTRY. >> LIKE WISE. I THINK THE SAME WESTERN (question) -- ARE THERE SITUATIONS WHERE BATTERIES HAVE BEEN REPLACED BECAUSE OF THE FAILURE RISK BEING TOO GREAT? HE YOU HAVE AN ANSWER TO THAT? >> NOT WITH RESPECT TO LITHIUM- ION. BUT WE HAVE REPLACED CHEMISTRIES LIKE LITHIUM PCX. WE DID NOT HAVE A GOOD REFLECTION OF WHAT THE ACTUAL ENVIRONMENT WOULD BE. FOR INSTANCE, IN THE ARBITER (orbiter), WE WANTED TO PUT IMPACT SENSORS ON THE WING SO WE COULD UNDERSTAND WHAT WAS GOING ON. AND IF AN IMPACT OCCURRED. SINCE WE DID NOT UNDERSTAND THE ALIGNMENT OF THE TEMPERATURES, WE ACTUALLY REFUSED TO ALLOW THEM TO USE THE BCX CELL BECAUSE OF IT BEING EXPLOSIVE. SO, YES, BUT NOT WITH RESPECT TO LITHIUM-ION. |
Some additional test flights?
Arguably this is more relevant to the 787 grounding issue than specifically to the batteries and chargers issue, but I noticed on FlightAware several reported flights reported as 787 flights operating under the ID BOE5 out of San Bernardino International in the last few days.
The FlightAware link for BOE5 is: Boeing #5 Flight Tracker ? FlightAware While I've seen seeing a small number of apparently spurious taggings of flights as 787 flights for weeks (mostly presumably false data-entry on ANA Frankfurt-Haneda operations) these KSBD flights seem plausible. In BOE5 flights listed as of the moment of my posting, there appears to have been a positioning flight from Boeing Field to San Bernardino on April 13, with subsequent daily or more flights out over the ocean in a generally SSW direction. The tracking data seem erratic, possibly partly because of the over-ocean positions. My guess is that these are real 787 flights. Does anyone know more? |
Arch,
Made a few inquiries on BOE05... ZA005 is in San Bernardino conducting testing to demonstrate the performance of engine improvements provided by General Electric. GE’s second package of upgrades for the 787’s GEnx-1B engine was certificated by the FAA on April 12. That’s engine-only certification. This week’s San Bernardino flight tests are working toward the certification of the upgraded engine and plane together. |
The NTSB just released the agenda for the April 23/24 hearing on the 787 Battery.
Investigative Hearing Agenda Japan Airlines, JA829J Boeing 787 Battery Fire April 23-24, 2013 It seems odd that the press is currently reported that the FAA will sign-off on the battery fix today... |
Press Release – FAA Approves Boeing 787 Battery System Design Changes
Press Release ? FAA Approves Boeing 787 Battery System Design Changes The FAA will publish next week the final directive that will allow UA to resume operations of the 787. It is expected other regulatory agencies will follow shortly to allow the 787 to resume services worldwide. |
Well, this will certainly make some some entertaining conversations at the hearings next week...
|
So how reliable is the modified battery expected to be now if there is still no root cause detected?
|
More reliable than the previous design but how much more reliable will only be revealed after some time in in operation has passed.
Some of this increase in reliability will unfortunately be masked by better working practices on the ground, which seems to have been a major cause of batteries going 'low' and having to be replaced. SoS |
Speed of Sound
More reliable than the previous design but how much more reliable will only be revealed after some time in in operation has passed. Unfortunately, a bit of service history can do wonders to :mad: up that original analysis. And waiting for statistical samples to set those numbers right again just isn't in the cards economically. Boeing (Thales, GS Yuasa, etc.) are going to have to trace these failures back to that mysterious root cause and put in place a plan and process to eliminate it. Only then do they get to go back to a clean sheet of paper, reliability wise. Yes, there will be an overhaul of the manufacturing process to eliminate contaminants, for example. But until the presence of contaminants in statistically significant samples of existing production runs can be shown, that's just guessing at the cause and the efficacy of the fix. |
Well, the hearing is currently ongoing...
from the FAA: "THERE WAS A REQUIREMENT TO TEST THE BATTERY TO INDUCE THAT CATASTROPHIC THERMAL RUNAWAY FROM MR. SINNETT DESCRIBED TO SEE WHAT HAPPENS. WELL, AN ALTERNATIVE APPROACH, RATHER THAN TO SEE WHAT HAPPENS, IS JUST DECIDE, IT IS CATASTROPHIC, WE MUST PREVENT IT. THERE IS NO NEED TO TEST A CATASTROPHIC CONDITION. YOU ALREADY HAVE ASSUMED IT'S CATASTROPHIC. YOU JUST PREVENT IT." In a nutshell, it appears that the FAA doesnt care about testing, thermal runaway, or the cause..they assume that all of that is a catastrophic failure, so you dont even really need to test for any of this. The catastrophic failure simply needs to be contained, hence the lifting of the flight restriction with a better box. Both the FAA and Boeing said that neither event had an effect on the aircraft... The venting of the EE bay was an odd response from Boeing. The system has to detect the smoke first (or in their explanation, the 'odor') then the system has to re-configure to vent to the outside, and this takes time to do, so there will be 'odor' into the aircraft. |
I know, I know...there was never any fire, there is never any smoke. :suspect:
|
Airplanes have outflow valves, sink drains, and various other holes that already vent to the outside. All another vent will do is allow the outflow valves to close a bit more...
|
Just out of interest, whilst carrying out some research on Li-ion cells for EV's last year, i had a couple of occurrences of thermal incidents.
i actually found the root cause to be back EMF spikes from the electronics i was using, and that it could set up a frequency resonance making the cells "pant" until internally breaking down and letting the "odour" out. Just thought i'd share that with you. GB. |
Bye,
That is interesting because the last speaker was saying that the continued focus on the event would be on the grounding system of the aircraft, how it is isolated and related. Another good question to Thales was why is the system meant to protect the battery, the BMU, located inside the case with the battery cells themselves. |
Query to GS Yuasa:
>> OKAY, THANKS. JUST FOLLOW UP ON THAT. HAVE YOU HAD IN THESE PARTICULAR DESIGNS, HAVE YOU SEEN ANY EVIDENCE PRIOR TO THE INCIDENT OF ANY INTERNALLY SHORTED CELLS? >> NO. >> THANK YOU. |
When asked about the BMU's location, Thales responded that the closer the BMU is to the cells it is monitoring, the better.
When asked if there was any benefit to having the BMU external to the containment vessel, Thales responded that the BMU is isolated somewhat from the cells themselves in the containment vessel (even more so, now, in the new design) and they felt that having the BMU inside the containment box was the logical way to proceed because it prevented a failure risk due to connection problems. The decision to place the BMU in the containment box was made by Thales and GS Yuasa. EDIT: Thales is recapping their statement and noted that the BMU has thermal disconnects so it sounds like even if the cells enter thermal runaway and damage the BMU, these disconnects would trip and kills electricity flow to and from the cells in the battery pack. |
52 bolts for the lid, 51 more to go..take one down, pass it around...
http://boeingblogs.com/randy/images/AOG-story-2.jpg EDIT: Dont know about you guys...but since one uses the bolt head to tighten (and measure torque), not the nut...that hes got the bolts in bassackwards....(the ones on the bottom are really going to suk trying to tighten....) |
I think there may be a typo in the article "NTSB hearing on 787 batteries reveals Boeing shift on testing", by Stephen Trimble Washington DC, linked below:
NTSB hearing on 787 batteries reveals Boeing shift on testing Where the article says, "In neither incident did the battery failure prevent a risk to the overall aircraft, ...", I think it should say,"In neither incident did the battery failure present a risk to the overall aircraft, ..." [I see that this typo has now been corrected.] |
I watched the entire proceedings and indeed on multiple occasions testimony was given, including by Mr. Bahrami, that neither NH692 nor JL8 was at risk of hull loss so yes, that is a typo.
|
United 787 KLAX to KSKF today
I've been looking at FlightAware for 787 flights several times a day lately, expecting to see a flurry of the Boeing aircraft caught on the ground before customer delivery going up for B-1 flights and such. But, aside from the engine testing flights ending last week under the ID BOE5, I've not been shown any in flight so far (the aircraft type method only detects aircraft in flight--though with a flight number you can see history as well).
Instead, today, I saw a flight under a 4-digit United flight number listed as a 787 flying from Los Angeles International to Lackland AFB. While this could just be a mis-attribution, I'm inclined to guess it was real. LAX was listed as the location where one of the United 787s was stranded, and I believe that some kinds of 787 work get done at Lackland. The past history of the flight number did not show other KLAX to KSKF operations under that ID recently. If it was real, then either someone gave special dispensation for the flight to be operated without the battery fix, or this is a bird that got the fix in already. Can anyone here correct, expand, confirm, or deny? |
I can check it out, do you have the designator?
Edit: got it 6850 |
UAL 6850
This link will allow detail to be seen for the next few days for the FlightAware listing of interest. (assuming PPRUNE forum software does not corrupt it).
The line of interest is for a flight from KLAX to LSKF departing KLAX at 11:19 a.m. PDT on 4/23/2013. UA 6850 on flightaware UAL 6850 (edit: you got the answer before I replied, but I'll leave the link up in case it might interest someone else) |
CHICAGO (AP) — United Airlines says it flew one of its 787s to a Boeing facility in San Antonio on Tuesday for the battery fix it needs to resume flying.
United has six of the planes. They've been grounded worldwide for three months because two of them had smoldering batteries. Boeing's proposed fix has been approved by the Federal Aviation Administration. Last week the FAA approved non-passenger flights for the 787 like the United flight that left from Los Angeles. United Continental Holdings Inc. says Boeing Co. workers will install the fix, with help from United mechanics. Boeing has said the battery system modifications will take about five days per plane to install. United has 787s in its schedule for May 31, but it has said that flights might resume earlier. |
airworthiness factual report error
In the airworthiness factual report there appears to be an error on page 16 concerning the JAL APU start power consumption.
The Flight Data Recorder report shows measurement DCBus_APU_Battery_Current (A) in figure B-12 on page 10B-13 only discharging an average of about 20 amps for the APU start with a momentary spike up to 30 amps during the 35-second discharge. This would only be 640 watts average with the spike at 960 watts, not the 9.6 kW (32V x 300A) mentioned in the airworthiness report. Some of the other power figures in that paragraph appear incorrect also and should be re-checked. In addition I wanted to point out that same FDR current data also shows that the APU battery was constantly being overcharged by trickle-charging at 1 to 2 amps during the 14 minutes between Last Engine Shut Down and the APU Shuts Down event. The Securaplane battery charging patent #5,780,994 is based upon a Ni-Cd battery charging profile and assumes a trickle-charging phase of indefinite length following the fast-charge phase. GS Yuasa does not include trickle-charging in the CC/CV charging procedure found in the LVP10-66.pdf data sheet for the cells, nor does any other manufacturer of Lithium chemistry batteries. The CT Scan report also provides evidence of overcharging in the scans of the "normal undamaged" Main battery. The cell walls are clearly seen to be bulging outward and there may be cell-to-cell wall contact. This swelling of the cells is also seen in the CT scans shown in the JTSB reports for the "undamaged" APU battery of the ANA aircraft. I have a mechanical load analysis which shows that only a couple of psi delta-pressure is necessary to deform the 0.031" stainless steel material used as the cell case. A deformed cell case would likely cause internal short-circuit contact of the current collector bars to the case leading to cell thermal runaway such as was experienced in both battery incidents. The source of the pressure delta could be internal due to overcharging, and/or external due to operation at reduced atmospheric pressure such as in high altitudes (e.g. 6000 ft). |
Perfect for spotters corner
There was a single United 787 parked out in the open at the south of the western maintenance area at LAX about 2 weeks ago. Is it still there?
|
Surprised!
When I said in post #742 (thread 1) that there is:-
No powered plane without fire Aeroplanes have been living with fire (in their engines) for over 100 years. This COULD be a precedent for permitting (inadvertent) fires in another power source, the batteries, provided it was as well contained as the engine combustion??? I did not seriously think that they WOULD do it. PS I accepted the correction that there are some powered aircraft without fire. |
Oh but we meant to do that
In the new set of documents that was just released on the NTSB Docket site. On docket # SA-536, exhibit # 17-A, Airworthiness Excerpts from Boeing Battery Specification Control Drawing:
page 89, section 3.2.4.13, Charging Requirements The fully charged battery shall accept continuous overcharge at _ V without explosion or damage to the battery case. The blanked out voltage was redacted due to proprietary concerns. So it looks like Boeing wrote a requirement on the battery that might be fine for Pb or Ni-Cd but violates the fundamental law of Lithium battery chemistry... |
Something I heard the other day.
The battery vent indicator burst-disc keeps blowing off in flight. The fix is to place the disc at the other end of the vent tube. IE. at the battery containment box. It is a weekly check item to ensure this disc is intact. The only way to check it is to remove the 52 bolts from the lid and do an internal inspection. Takes about 3 hours apparently. This may well be a load of BS as I haven't had it confirmed yet. Posted from Pprune.org App for Android |
Yesterday, the guy from Boeing stated that if there are any issues with the battery, there is an alert to the crew, and that any battery alert prevents dispatch.
It should be interesting to see how that plays out... edit: awblaine...note post#24 above. |
How could bursts have been frequent
Originally Posted by TURIN
the battery vent indicator burst-disc keeps blowing off in flight.
Famously there was just one in the certification plan for the revised battery system. Also, I think, a handful under flight number BOE5 handling certification for an engine upgrade (mostly last week). Other than that, the reported recent flights (UAL ex Los Angeles, Qatar ex London) seem to have been relocations still carrying the old system. My doubt on the runup to the situation does not address the possible truth of the weekly inspection requirement, which would be an unwelcome addition for several reasons. Still, 3 hours seems rather a lot unless the paperwork enormously outweighs the inspection work. Please advise if you get updates on any aspect of this. |
Yes, I took it with a pinch of salt but I just thought I would throw it out there just to get a confirmation. 3 hrs seemed a bit excessive to me too.
Posted from Pprune.org App for Android |
Well, look at set up, then unscrewing 52 bolts...doing what you have to do, then placing and tightening 52 bolts...(at Union scale)
Given the picture, one could easily see 60 seconds per bolt sequence... |
14,000 cells built since 2001
and never had an internal short-- according to the GS Yuasa representative in today's hearing. These are the industrial cells of the same construction as the 787 cells, but using a different chemistry.
|
So it looks like Boeing wrote a requirement on the battery that might be fine for Pb or Ni-Cd but violates the fundamental law of Lithium battery chemistry... The transcription mentions the cell OCV as 4.55V, then a little later reconfirms this figure by stating that for the battery - We also do a test where we charge at 36 volts for a long time |
Installation Progress, 10 + 9
Michael Mecham posted on Aviation Week's Things with Wings blogs a comment attributed to Boeing Chairman and CEO McNerney that the fixes "were installed" in "10 fleet aircraft and 9 production aircraft". That sounds like "all done".
Mecham battery progress post However, a Boeing VP posting in his own voice on his own blog, VP Marketing for Boeing Commercial Airplanes, describes it as "We’ve started installation on 10 787s already in the customer fleet, as well as nine production airplanes. The bulk of the fleet retrofits should be wrapped up by mid-May. 787 deliveries are expected to resume in early May." Tinseth blog (look for the second paragraph of the entry which first mentions the quarterly earnings report. It is the top entry at the moment I am posting, but will move down). I don't usually expect the Marketing channel to have the more accurate story, but in this case my bet is on Randy, not on McNerney as quoted by Mecham. Boeing has elsewhere described the installation as taking about 5 elapsed days on an airframe, and I think they did not start customer fixes nor most in-process birds until the approval came through. I'm talking about bending and cutting metal and composite--not about pre-positioning people and materials, which clearly happened. Randy comments in his post that he was in Ethiopia at the time of writing. I'd guess that may hint that the widespread story that Ethiopian may be the first airline flying seems more likely than some may have thought. |
It is interesting the amount of detail that has been shown for the box in the rear bay. I bet it is a real bitch getting that thing installed in the fwd EE bay....
|
@mm43
Having reviewed parts of the Day 1 NTSB hearing, and looked at the rough transcription; it seems that no one has questioned the over-voltage charging regime, nor the CV trickle charging. The transcription mentions the cell OCV as 4.55V, then a little later reconfirms this figure by stating that for the battery - Quote: We also do a test where we charge at 36 volts for a long time So, it would appear that the 36V [36.4] figure has been redacted from the Airworthiness Excerpts now released. Actually, FDR at BOS shows charging after the first cell beginning to short - up to 4.57V for the remaining 7 cells - 32 / 7. |
Acceptance testing at ~5000 ft
According to Thales in the Battery Acceptance Test Procedure general ambient conditions for all tests were performed with atmospheric pressure from 84 to 107 kPa, temperature at 25 +/-10 C.
The Thales Climatic Environmental Qual Test Report has altitude, decompression and overpressure testing, but all the values are redacted. If cabin pressure is held at that of 6000 ft altitude and also maintained all the way into the Main and Aft E/E compartments, then the delta-pressure across the cell walls is on the order of -2.9 psi, which will cause the cell cases to swell and bulge out such as is seen in the CT scans of the exemplar batteries from both Boston and the ANA battery events. |
More documents released....
The online NTSB document access system (http://dms.ntsb.gov/pubdms/search/do...251&mkey=85973) just had 36 new documents added to it, most relating to new certification. Have not had time to read any yet.
|
| All times are GMT. The time now is 16:11. |
Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.