Dreamliner Grounded.
 

I guess they thought Lithium Ion batteries were a good choice, .....based on how wonderful Nicads were?

Never failed to amuse at school when guys would argue for Nicads, half a day spent on battery overheat procedures...then when you go to a Lead Acid battery...for a tenth the cost, no inspection and deep cycles... INOP the temp guage, rip out two pages of checklist items. Now it's like car battery...either works or it doesn't.

Boeing must have some rocket scientists working there.

Are you a mind reader? Were we separated at birth? Spooky...

:ok: :D

Hi TheRobe,
L1011s had NiCad batteries.
See page 25-6 of MMEL Electrical Power for "condition light" (read battery temperature)
http://www.caa.co.uk/docs/33/srg_acp_l1011_rev1_all.pdf

We never went back to Lead Acid Batteries - the battery charger technology simply improved.

Seems to be a control issue
 

The Yuasa batteries are managed by a Thales control system, allegedly quadruply redundant, which is tasked with monitoring the batteries charging and discharging currents as well as its temperatures.
There are now reports that suggest both aircraft may have had used parts from a bad lot of circuit boards in the battery controller. This seems more plausible to me than two random battery failures.
The real shock imho was the poor containment performance of the design, with fumes vented into the cabin and cockpit as well as ejected battery fluid bathing much of the battery compartment. This was not supposed to happen, fumes were supposed to be vented and fluids contained.
Both the FAA and Boeing should be grateful for this wake-up call and take advantage of the opportunity to do a more jaundiced reappraisal of how well the outsourcing of critical subsystem design and assembly really serves the aircraft buyers and the travelling public.

And oft said by aircraft manufacturers when a brand new type has been
shoved into airline service.

If you want to do a bit of insightful research you will learn that both Nicads and lead acid have various pros and cons. Which is best for a particular operator is for him to determine, and may be dictated by fleet size, operational environment, economics, whether the airworthiness authority allows a swap (STC perhaps) etc

Previous discussion here Battery - Lead Acid vs. NiCad preferences. [Archive] - PPRuNe Forums

Despite misconceptions, lead acids may have a thermal runaway. Photo of such in a car.

http://mathscinotes.files.wordpress....eryrunaway.png.

All battery systems may be driven into thermal runaway if severely overcharged for a prolonged period at high temperatures. The lead acid battery, when driven into thermal runaway, will fail in such a manner that the aircraft is not endangered.

All battery systems in thermal runaway will produce large amounts of hydrogen and oxygen gas which must be vented outboard of the aircraft.
A nickel cadmium battery in an uncontrolled thermal runaway may get so hot that the battery separator melts causing shorts within the cells and the cell containers melt causing ground shorts to the outside stainless steel container. The result of these shorts is that the battery may catch fire, explode, or the resultant arcing may burn holes in the outer stainless steel box and surrounding aircraft structure. For this reason, the nickel cadmium batteries are equipped with temperature sensors and temperature warning systems.

The lead acid battery in thermal runaway will reach only a relatively moderate internal temperature (approximately 260° F) at which point the water in the electrolyte vaporises and the battery vents steam. As the separator is glass, it is unaffected by this low temperature. The loss of water caused by the venting reduces the conductivity between the battery plates and the battery ceases to accept further charge. The battery slowly cools.

All aircraft I flew professionally only allowed the use of Nicads, no STC being available to allow lead acid, though that has now changed.

http://www.concordebattery.com/otherpdf/finalfaapma.pdf

Battery types
 

Brian Abraham:

Quote:

---

...Photo of such in a car.

---

The photo seems a NiCd pack. You may see cells inside and one outside the pack at left.

These batteries gave us "Fault tolerance" and "Graceful degradation". Essential characteristic of a good design.

In general we can say lead acid are less critical.

rudderrudderrat:

Let´s hope for the same in 787. The less damaging scenario.

Not battery issue? If so, would be the less damaging scenario
 

etudiant:

A severe malfunction of the battery associated circuitry (charger, etc.) could explain the occurrences. This scenario certainly was not considered in the design. There are limits to redundance, etc.

I hope for the chargers / circuitry malfunction scenario. The "less damaging". If due components (not the design) less worse.

Whatever the case, LION batteries for planes are new technology...so my guess is that they will deep cycle them more often, not try to charge them so hard, go to larger capacity batteries..whatever...always a solution.

Given the hysteria, a lead acid retrofit would be an easy fix until they get the kinks out of the LIONs.

The lead acid voltage drop off profile makes them not so useful. I guess thats why they all have nicads nowadays.

Any relevance to the thread?

None at all.

Photo is of one of TWA's Super Constellations, N7121C, damaged (though later rebuild with a salvaged forward fuselage) when a pressurisation test went wrong at Idlewild in 1959.

Thanks for the clarification. I thought it was a battery explosion. :{

Well, anyway, it's a nice picture. I mean, a nice airplane. Er, that is... had been a GREAT aircraft, and the photographer did a neat job. Is it a plain 1049 or a Super G? Have had a soft spot for the Connie since a 749 carried me a quarter of the way round the world in 1955.

The Constellation was THE dreamliner, so Glueball is bang on-topic - pun not intended. (Too many 787 nightmare-threads already.)

Over-pressurised when the front offside quarter light was open ?

I'm reminded of the new London "bendy buses" of a few years ago, now gone, which came from a "world-renowned" German manufacturer.

Shortly after introduction one was completely destroyed by fire. "An absolutely unique incident" said the manufacturers' management.

Then a second was destroyed the same way "the most amazing and unrepeatable coincidence" said the same management.

Then a third one went up in flames as well. And then they were all taken out of service. And then it was discovered the issue had been identified in development, but was suppressed somewhere along the way ........

- probably the engineer going '"WTF was that bang....? I'll have a shufti.............Did your ears pop too?"

You can always trust Sky news.
Deliveries of the 747 to airlines are stopped as an initial probe into the plane's mishaps points to overcharging of batteries.:ugh:

Naive Question
 

Have LION batteries been used on any military a/c?

Or is the 787 the 1st application in any a/c?

Batteries
 

Hi,

All three battery types discussed here have their pros and cons. Lead
acid are probably the most robust and some versions use gell instead
of liquid electrolyte, which makes them even safer in terms of electrolyte
spills. Major disadvantage for a/c use is the poor energy density to weight
ratio. Aircraft style nicads are also quite robust, have long life and are
lighter than lead acid for equivalent capacity. Both the above will withstand
moderate rates of overcharge with no damage at all, other than electrolyte
loss. Lithium Iron are well proven, have been in use for years and are quite
safe, despite the occasional scare story re portable computers. However,
they have far more critical requirements in terms of charge / discharge
currents, voltages and temperatures. Energy density / weight ratio is very
high for these batteries.

I don't know what the dc rail is in the a/c, but if at 270v or so, as
someone else mentioned, it becomes very difficult to ensure that individual
cells within the pack match in terms of charge / discharge characteristics.
If there is mismatch, either in capacity or self discharge, some cells
discharge faster and will take differing times to recharge. Over time,
some cells become overcharged, while others never reach full capacity. This
is exacerbated by high charge current and discharge loads, in relation to
battery capacity.

The best way to solve this is to have separate monitor and charge circuits
for each individual cell, but his becomes expensive for large groups of cells.
Users like telcos do monitor in this way to maximise battery life, but
typically in groups of 3 or 6 cells. On a 28v system, there are typically 14
cells in series, whereas a 270v system needs 135. This just makes the problem
of mismatch monitoring more difficult, especially for Lithium Iron.

Yuasa are a world class manufacturer and my guess is that there is a problem
with the charging / monitoring electronics, or cooling. That or the batteries
are being driven too close to their design limit to save weight...

I had a lead acid battery do the equivalent of a thermal runaway in a helicopter. After emergency landing the air base's firemen emptyed a 6' high CO2 extinguisher on the battery, and an hour later it was still boiling. Lots of thermal mass!

syseng68k

Thanks for a splendid overwiew. In an absence of reliable data, it is most welcome. My guess is that there will be no "gotchas" here, the silence from the principals is more indicative of embarrassment than the desire to protect new "magic".....

Spec. Operations. Maintenance. Safety.

At a guess, this new airplane was the victim of unwarranted excitement followed by intense worry, and an inability to accept some limitations in an ego driven project. Leading to secrecy, then desperation..

What a surprise.

It is a BATTERY. With a useful life, a performance profile that demands monitoring, and a payoff that demands attention, and 'useful insecurity' on the part of the operator/builder.

Insufficient capacity, (spec), overconfidence (ops), and fear (the tail wags the dog). No one, NO ONE, expects perfection. In a wild flurry to avoid the perception of imperfection, the project is put on the chopping block.

Nevermind, when all else fails (it might) there is the RAT.

@syseng68k:
 

Its just on the 28Vdc.

ACbus 230/115v

270vdc for ECS compressors; RAM fans; Hydraulic pumps and nitrogen generation system.

A news source recently quoted a Boeing employee saying there was at least one (LiIon, not nesc same type) on the International Space Station, that the F35 and F22 have them and that there is at least one on the A380. They also quoted 1.3 million actual flight hours for the battery type in question, so its not all new, but has been proven in service already.

From that, I would suggest that this is either a manufacturing fault in the batteries or a problem with the circuitry/management of the battery.

I very much look forward to finding out what the probelm is, as I think most of us do!

The B-2 uses them.

have to check, but F-22 and F-35 may also use them.

The Nickel metal hydride batteries are used in the Toyota Prius after an attempt with the Li-ion doofers. Those nickel ones don't have the energy per weight/volume, but are less susceptible to burning up when over-charged. Less charging system protections and such requirements, so easier to engineer and employ.

Secondly, although the Li-ion ones dont have pure lithium ( highly reactive to water), they can still react to water once going into the thermal runaway stage. Damned hard to put the fire out.

We don't need to go back to lead-acid or even NI-Cad, but the new Li-ion doofers seem a little too risky for the applications in aircraft.

Hard to fix with so many involved
 

Afaik, the overall power system in the 787 is a UTX responsibility, with Thales managing the auxiliary power aspects. Thales in turn ordered the batteries from Yuasa, but deleguated the battery management to Meggits Arizona based Securaplane subsidiary, which built the chargers. Some reports are circulating that a defective batch of PC boards made in Mexico made their way into the charge controllers.
How Boeing or the FAA for that matter are ever going to get to the bottom of this daisy chain of buck passing and determine both a probable cause as well as a confidence restoring fix remains TBD.
My guess is a switch to NiMH batteries, to distance the plane from any taint of 'lithium batteries on board'.
That might mean a grounding stretching well into spring, while the new approach is certified.
Does anyone from the regulatory side have any insights to offer?

I have always been a fan of Boeing, but I think they screwed the pooch on the 787. In an effort to reduce costs and put the screws to their own labor unions, they lost complete control of their supply chain. They outsourced not only production, but development of many components. Some of the subcontractors can handle it, some could not.

I think they will solve this battery problem fairly quickly, but I also believe it is just the tip of the iceberg.

I hope I am wrong about this last part, but I don't think so. The 787 has many features never tried before on a commercial aircraft. Maybe the B2 or F22 have some of the same stuff, but those aircraft were low production run, VERY low flight time airframes. They will never be put through the same number of cycles that 787s will in 2-3 years, let alone 20-40 years that the 787's will be in service.

Batteries
 

syseng68k:

The focus of the issue! :ok:

Indeed requiring a quite "complex" management. (algorithms)

:ok: and why not to separate better each cell from adjacent? The weight could be similar and the volume would compensate for the better safety under higher temp cell operation, an usual condition.

8 cells of 3,7 V ea.

Some of the subcontractors can handle it, some could not.
 

USMCProbe

Outsourcing demands very wise managers, i agree with your concern.

Li Ion batteries requires better "management"
 

Hi, gums

I would complement:

She are wonderful but critical and requires competent management.

The model in my mind is: The problem is not with the battery.

"Handle with care"
 

Jetstream Rider:

The model in my mind is: The problem is not with the battery.

She may present terrible surprises to us
 

Bear Lyman,

Unfortunately when the wonderful and critical battery fail she does an scandal: Heat (intense), smoke, hot and evil fluids and ultimately FIRE.

This is a very special kind of failure behavior. :E :sad: :} :mad:

The problem is that with any project of such complexity and wide range
of technologies, there's no alternative but to outsource a lot of systems
and parts. Systems get more complex and need specialist manufacturers to
build them. Engines, avionics and more have been sourced this way for decades.

Duff batch of charger control boards may be true, but where was the inspection
procedure for incoming goods ?. Why didn't the BITE / system diagnostics pick
up the fault once the kit was installed ?. How much testing had been done under
worst case conditions over long periods ? and, why wasn't the battery electrically
isolated once the temperature or charge characteristics exceeded limits ?. Duff
batch of boards from *Mexico* ?. That's ok then, problem solved, or a smoke
screen ?.

Sad day for Boeing though. As slf, always thought of their kit as first class
and teething troubles like this probably won't change that view. The 380 intro
wasn't exactly trouble free either, just for the balance :-)...

You talk a lot of sense syseng68k and make it easy for a low tech chap like myself to understand. Thank you for that.
I read in the paper that the 787 has four times the battery power of a 777, if that is correct why would that be?

787 innovations
 

ian16th:

Boeing introduced Li Ion as the main battery (single) and for APU start for the first time to an airliner.

The toll for that is being paid. IMO not because a problem in the selected batteries. Because the more complex management she requires. I hope (and somewhat believe) a tweak in the management System will solve the problem.

But there are other possible and probable causes like defective parts or even algorithms.

TNKs, RR et al.

We went thru this 40 years ago with the power supply system for the Viper.

The whiz kids working the flight control computers were given carte blanche. So the basic run-of the-mill folks that did the power supplies provided the specified volts and amps. They also had a simple emergency DC power system using PMG's and run off bleed air from the engine versus the hydrazine-powered "real" emergency system.

Unfortunately, the computer folks used voltage regulators that did not tolerate over-voltage, and would shut down when volts got above "x". So when an uncommanded EPU came on line, the PMG generator exceeded the critical voltage and POOF! No more flight controls. Not good.

We fixed the problem and also had newer solid-state voltage regulators that could handle 90 volts versus 37 volts +/-.

With known problems of the Li-ion batteries going out of control due to over-charging and such, my personal engineering decision would be to use the nickel-metal ones and have slightly less amp-hours, a little more weight, but be safe.

Options to kill the problem
 

gums:

The engineering task force certainly will provide options to the high rocks of the involved players: Yuasa, Thales and Boeing. From an strategical POV the issue deserve a strong and clear response. The change of the battery type has this "feature".

But there are chances the problem is simpler. I personnaly would bet in how the wonderful and critical batteries are being "managed". The engineers will have this info if not yet and in a scenario of this type the not trivial retrofit could be not necessary.

Another alternative (not immediate to introduce) would be have two options of batteries and associated devices. This would not be "free". There are reasons they specified the Li Ion as main and APU batteries.

I question why they not used two as main. With different "regimes" could be nice. In R&D we brainstorm continuously. :)

I can imagine how the problem was handled by the people involved. :)

Regards,

PS

My son (copilot during the RTW flight) made his first solo by December 16. :)

Gums - concur that sentiment - suspect that increase in weight may not be too much of a problem - but how much bigger would a nickel-metal battery be? Would they have the space? Looks pretty size limited from the pics I have seen :confused:

yeah, Feline, I am not a dinosaur and flew the latest and greatest fom 1971 until they made me quit.

I also had an engineering degree and fully understood all the workings of the aircraft systems, and the software. So I'll go with the best we have, but only after we fully undrstand the risks versus the perceived gain in performance or weight reduction or......

Not much different in form factor or weight. Just look at the Prius. Ten pounds on that sucker is a lot of weight fraction compared to 100 pounds on a 787. Hell, just one obese SLF would wipe out the weight savings, ya think?

I like the latest and greatest ( not to be just "cool"), but we have to make engineering decisions and production decisions. Safety is paramount, as they say.

787 is an engineering marvel from aero to mechanical to..... In the long run it's the stuff that you take for granted that bites you. And we learned that back in 1981 with the Viper power supply and computer power supply.