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FAA Grounds 787s

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FAA Grounds 787s

Old 6th Feb 2013, 02:19
  #641 (permalink)  
 
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The salient issue for me is one of safety, and the public right to duty of care from Boeing and the airline. Not to mention strict enforcement of the letter, and the spirit, of the regulations....

If the story is true that Boeing was changing out virtually all the batteries, for any reason, if the removal and replacement was on an accelerated schedule, that is a change of performance.

I am hopeful the true events become known.

It is especially critical if the Program of replacement was as a result of any particular and unexpected defect or failure. Any unexpected event presents the possibility of complete and critical failure, there is potentially a danger to the aircraft and passengers, on board and people on the ground.

I think most other considerations pale in comparison to the process involved in changing the batteries. I am sure the program was innocent, and proper.

Last edited by Lyman; 6th Feb 2013 at 02:30.
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Old 6th Feb 2013, 02:46
  #642 (permalink)  
 
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@RetiredF4,

Not so sure the ANA earth-wire is really much different from the JAL one. Difference is that JAL one has been damaged by fire and the ANA one hasn't. Exactly how much damage was caused to either wire when disconnecting the cable plug is anyone's guess.

A close-up of the JAL front of case is here
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Old 6th Feb 2013, 03:56
  #643 (permalink)  
 
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CockneySteve, Repeat after me the mantra of the business schools:Image over substance but your raison d'etre is to maximize your compensation.
Wow.

Just wow.

Kilo, you have demonstrated, in one broken-English sentence, exactly what is wrong with PPRuNe and why these fora need to become a pilots-only environment.

WT?
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Old 6th Feb 2013, 04:30
  #644 (permalink)  
 
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Unhappy

Time for a big-ass sanity check here, folks.

NiCd replacement - won't happen unless someone carves 2 extra cubic feet of available space in the EE bays.

Grounded until next year... Boeing fanboys didn't wish this sort of calamity on Airbus, even when the A380 SHED PARTS during her high speed test. Nor did GE engine fetishists wish doom and gloom on Rolls-Royce when an RR Trent blew into pieces on the wing of QF32.

I've read these fora diligently, trying to learn - and found that I have learned more from common media than I have here.

Mainly due to the simple fact that common media is predictable - the posters and posers here are not.

Seriously:

"Those wires are too small to balance a charge current!!" even though the balancing takes less than 5 amps the the "small" wires are 18 ga.

"The cells are actually 6 cells because NO CELL COULD EVER DELIVER 65 AH!" - Really? Look under the hood/bonnet of your freakin' car.

and on and on and on.

What a tribe!

Son, I am disappoint - this crowd has gone so far down hill since, I hate to say, AF447, that it's not even funny.

Boeing haters gonna hate. Dips with no knowledge whatsoever gonna spout. The few [smart] folks who work in the industry gonna try, for a while, to dispel ever-growing fallacy.

All the while, every idiot with a keyboard and an internet connection is going to keep cranking out his or her own version of how the 787 operates, how much electrical power it draws, how the batteries are used, and why the batteries failed. And how many batteries failed.

Along with wailing, gnashing of teeth, self-flagellation, and perhaps the odd suicide or two, based on how a well-executed safety action could potentially "ruin" an airframer which has helped write many of the safety certifications honored by ALL the other aviation authorities around the globe.

In the mean time, the media will keep fishing these waters and publish all the tripe that seems new - which only seems new because anyone held accountable for mouth or pen would NEVER dare to utter such BS.

Ignoring now, good luck with what I can only call one of the greatest examples of pure pilot / ramper / aficiando HUBRIS I have ever seen.

Nothing will ever top this, folks.

A few of you have been absolutely stellar in trying to de-mystify what's going on.

Most of you have been asses merely trying to prove how "smart" you are, while merely proving that you don't know soy from wheat.


And you wonder why people worry about WHO is flying the plane they bought a ticket on...
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Old 6th Feb 2013, 07:23
  #645 (permalink)  
 
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"The cells are actually 6 cells because NO CELL COULD EVER DELIVER 65 AH!" - Really? Look under the hood/bonnet of your freakin' car.
Yes, lead acid can do it, Li-Ion not.

In the 787 batteries each cell-array (8) has 6 cells in parallel.
So, one cell has litlle over 10Ah.
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Old 6th Feb 2013, 08:10
  #646 (permalink)  
 
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I have been told that the peak discharge when starting the APU is 1000 Amps!
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Old 6th Feb 2013, 08:16
  #647 (permalink)  
 
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Rottenray,
Ok, I'll bite.
There are many of us who chose a professional career in aviation that does not involve flying aeroplanes.
Just as well, as you and all the other professional pilots would have nothing to fly, no one to maintain them, bugger all in payload and you would have to bring your own cheese tray!
Still, look on the bright side. Security would be a doddle.

Your arrogance does you no credit and is an embarrassment to the many professional pilots I work with everyday.
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Old 6th Feb 2013, 08:50
  #648 (permalink)  
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Well said Turin, after all pilots know how to fly aircraft, why should they also be an authority on electronics and batteries?

There appears to be some confusion over sub-cells, they are only there because of the prismatic construction of the cell, you cant bend the electrode through 180 with zero radius so you end up with sub cells, in a circular battery you can have continuous electrodes so it has no need of sub-cells, although there may well be multiple connections to that electrode.

Last edited by green granite; 6th Feb 2013 at 08:53.
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Old 6th Feb 2013, 09:06
  #649 (permalink)  
 
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Really? Look under the hood/bonnet of your freakin' car.
A 12v car battery is 6 two volt cells in a case.
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Old 6th Feb 2013, 09:12
  #650 (permalink)  
 
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after all pilots know how to fly aircraft, why should they also be an authority on electronics and batteries?
Yep, some pilots are also engineers with a university degree......
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Old 6th Feb 2013, 10:55
  #651 (permalink)  
 
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If I was flying on a 787 or any plane with LiI batteries at any point in the future, any concerns I had about a battery failure, charger failure, charger SW issue and even thermal runaway would be secondary. All these things can and will fail at some point in the life of the 787. That is taken for granted. There seems to be enough redundancies for the probability of it causing any hazard to the aircraft are pretty low. My primary concern would be the fire containment. ie if there is thermal runaway in a cell any resulting fire would be contained within the battery casing and any fumes vented outside where they can cause no harm. If this was addressed I would be happy to fly on a 787 tomorrow even without the root cause of the battery failure being found. If the fires in the ANA and JI incidents were properly contained I doubt the planes would have been grounded.

Last edited by Cool Guys; 6th Feb 2013 at 10:56.
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Old 6th Feb 2013, 11:15
  #652 (permalink)  
 
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@ rogerg "A 12v car battery is 6 two volt cells in a case." And so what ??

@ hetfield "Yes, lead acid can do it, Li-Ion not. In the 787 batteries each cell-array (8) has 6 cells in parallel. So, one cell has litlle over 10Ah."

Are you saying, hat LiIon-cell can have only max 10Ah capacity? Why is that?
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Old 6th Feb 2013, 11:26
  #653 (permalink)  
 
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Capn Bloggs. rogerg said there were six cells each of two volts, which is indeed the case. I think you were a bit quick on the trigger there.

I worked for three years as a chemist in a factory making car batteries. I know this much.

As I don't know about Lithium batteries or aircraft I shall now withdraw.
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Old 6th Feb 2013, 13:02
  #654 (permalink)  
 
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For simplicity:-
The voltage of a cell is dependent on the technology(Chemistry) employed

the storage-capacity is a product of plate(electrode) surface -area within that cell.

The discharge-rate is a product of the technilogy and configuration of that cell.

Where Automotive LA batteries are concerned, there are standardised cases and terminals (shape and position)

Within the cases there is potential for a few thick plates, or a lot of thin ones. the more plates, the bigger the surface-area and the greater the peak-current potential. irrespective of how many plates there are, within a cell, all the pos. plates are bonded together like the fingers of a hand. the opposite polarity are linked likewise interleaved between them with porous spacers between,-this allows current to flow between ajacent Pos-Neg. plates, whilst stopping warping/shedding from mechanically shorting the plates together. that's why you get different prices, weights and energy-ratings in what looks like the "same" battery.-

The net result is 2 plates/electrodes. in a compact space.
-in the case of a cylindrical cell a "sandwich" of long strip plates and insulator-spacers is wound exactly like a Swiss-Roll (a capacitor is mechanically very similar!) compact, but doesn't use square spaces efficiently.

Back on topic... Lithium Technology has the potential to store a lot more energy in a smaller, lighter package , than Nickel Cadmium or Nickel Metal Hydride...in turn , these have superior weight and energy-density to Lead-Acid

The major disadvantage of Lithium technology ,is it's intolerance to deep discharge and maximum -capacity charge.

Keep within those boundaries and you can make massive short term current demands and have low self-discharge rates (virtually ALL batteries will go" flat" if left to their own devices).- which is why it seems eminently sensible that the "screamliner" constantly monitors and conditions it's batteries....or is that "Should constantly".... If it had done, there would have been no need to swap-out so many as if they were "use and throw" torch-batteries.

IMO , the Yuasa cells are beyond reproach... the charging/monitoring interface between cells and the aircraft's wiring-harness is the trouble-spot.

The state of the main/apu/rat power-deliveries is immaterial...a properly specified and built interface should ensure the battery is charged/discharged within it's safe working envelope.

Test-flights "may" uncover a shortcoming, but I'd bet a pound to a pinch of sh1t that the problem lies in the charger-unit.

I suspect also that the internal battery controllers are intentionaly configured to make the unit unusable by the end -user in"tailored" failure-mode thus ensuring a steady replacement and "reconditioning" market........

HOW MANY REPLACED, AGAIN ? Someone's taking the p155 and damaging the cost-savings potential.......biting the hand that feeds..../ killing the goose..... ??

Last edited by cockney steve; 6th Feb 2013 at 13:11. Reason: tidy up some ambiguities/ omissions
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Old 6th Feb 2013, 13:10
  #655 (permalink)  
 
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ANA (probably) landed with battery cooling down

Hi,

When plane landed in TAK, very probably the battery was yet "out of circuit".

The rationale of this model was described in:

Post # 497 and

Post # 498

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Old 6th Feb 2013, 13:17
  #656 (permalink)  
 
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Are you saying, hat LiIon-cell can have only max 10Ah capacity? Why is that?
@mikkojuha

At least, I don't know Li-Ion cells (one cell) which has 65Ah....
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Old 6th Feb 2013, 13:25
  #657 (permalink)  
 
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Test-flights "may" uncover a shortcoming, but I'd bet a pound to a pinch of sh1t that the problem lies in the charger-unit.
cockney steve....then why replace only the BATTERIES as though the certificate depended on it?

question: As well as being 'self certifying', when did Boeing also become

"SELF INVESTIGATING"? Since BA038?? Before?

Objectivity is on life support......

I think a summary. A brief one.

Have not seen anything here that was not addressed by all concerned in the development and certification process.

Best efforts, best practice resulted in uacceptable failure trail, BY DEFINITION. The regulations were too minimal. If "Relaxed" to accomodate continued use, the Regulatory paradigm becomes a laughingstock, instead of just a wink wink....

At the very outset, the sham 'specials' were an obvious permission slip to utilize a technology that cannot be made safe for aircraft in commercial carriage. The recent hasty "Permission" to transport this "cannot be made safe" technology on aircraft only emphasizes the desperation of a failing attempt to salvage it.

I think Lithium Ion power on aircraft is done.
I think any "Test flights" are pretty much for show. Or to position a/c, as EEngr says.

Last edited by Lyman; 6th Feb 2013 at 22:19.
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Old 6th Feb 2013, 20:12
  #658 (permalink)  
 
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I'd like to see that flight test plan. IMO, a flight test isn't the right way to verify proper operation of the charger/battery/load system. One flight, or a couple of flights won't prove anything. The 787 flew how many hundreds (thousands?) of cycles without a failure. The same will happen here.
I'd say the test flights will be to prove a theory or demonstrate a reproducible error/issue.

Simply replacing a part and flying it to prove the issue doesn't re-occur won't be very convincing unless they intend to test fly for 50k hours...

Last edited by peter we; 6th Feb 2013 at 20:12.
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Old 6th Feb 2013, 23:32
  #659 (permalink)  
 
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Speaking as an electrical engineer who has designed battery charging systems for exotic battery packs in the past I would suggest that Boeing may be trying to reproduce conditions that are difficult to do on the ground. If I was working on the problem I would want to insurument the holy ()*^ out of the entire system and then put it through simultaneous stresses- altitude, temperature, g loading, load dumps from the engines, etc. Maybe then I could get a clue as to what might be going on. The easiest way to do this might be a flight test.
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Old 6th Feb 2013, 23:49
  #660 (permalink)  
 
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Piper Driver:

Agreed - I've been thinking that the only way to reproduce the fault would be
to build a test rig with battery, charger and associated kit, then put it through
test cycles that simulate actual operation and beyond. Ideally, put it all in an
environmental test chamber to allow temperature cycling as part of the process.
This would perhaps be faster than flying the a/c

Perhaps they have this already, but the lack of info after nearly a month suggests
that the problem is far from obvious. It's starting to look increasingly likely that
some operation at the corners of the battery / charger spec may be triggering a
software bug, or battery management hardware running beyond design limits...
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