Ian W:

I'm going to look b awkward again, but laptop batteries are rechargeable and
use a different chemistry. We all know some laptop batteries have had issues,
but it's not really relevant to this thread.

Ancient Mariner's post (thanks) triggered memories from years ago about
the volatility and safety of early lithium batteries, primary non rechargeable
types, but haven't heard any reports for years in that respect. My guess
is that the unsafe chemistries from years ago are no longer used. The cells
used in the elt are lithium manganese, nothing like the lithium ion types used
in laptops. The lithium managanese types are also the most common chemistry used
for consumer products, lithium coin cells etc, which are well proven and safe.

Good overview in a Wikipedia article here:

Lithium battery - Wikipedia, the free encyclopedia

For the umpteenth time !
 

LI -x batteries do NOT need Oxygen to continue to flame- the chemistry is such they generate thier OWN oxygen.

ELT batteries are NOT chargeable

ELT is not normally connected to Aircraft electrical system- note I said NORMALLY - but ' sneak" circuits due to poor grounding, flaky connections, crossed wires, etc ** could ** possibly exist. Battery protection diodes can fail for example internally, etc. LI-x fires can be like a cutting torch.

Model airplane LI-x batteries can and do catch fire if abused/shorted/etc but they ARE rechargeable.

:*

Technology improves but "safe" never means absolute safety, there is always statistical chance for this first occurrence. "Today" is probably better than "years ago" but far from perfection.

DWS and Ancient Mariner, after reading your posts and looking at the picture of the burned battery, It seems like I have a lot to learn about Lithium batteries. Some of them are really scary. Maybe, like the battery in the closet, the one in the ELT caught fire for no apparent reason without even needing "crushed wires". That is extra scary. In a hermetically sealed box, it might be more like a bomb! I'm making the lithium battery too analogous to more common batteries I'm accustomed to. I may not always be right, but I'm clever enough to know, when I need further study. As much as I know, I learn a lot from our brainstorming, and appreciate everyone's patience with one another.

Environmental conditions can be critical
 

Ancient Mariner showed photos (many thanks) and said:

[The batteries were taken straight out of the box and put on shelves, they were airfreighted! to us and we could not find anything wrong with the boxes. ]

i wonder if the reduced pressure environment of the freight cargo hold may have been an overlooked factor causing internal cell damage that later erupted in the storage room (e.g. venting, cell wall flex and distortion, expansion of the foil roll, shorting of internal electrodes to foils or case, etc.) A cell may look fine on the outside but be damaged and slow-cooking on the inside.

As Reuters reports, ANA found damaged wiring in their ELTs.

787 fire investigation looks at pinched battery wiring | Business & Technology | The Seattle Times

"The two sources suggested that Honeywell might have replaced the batteries at some stage before delivery of the jet because the devices sat on the shelf during the years-long 787 program delays."

Sat on whose shelf? Are these ELTs 787 specific parts? Or are they used across various models? If its the latter, then I'd expect Honeywell to pull stock and ship it as various orders came in. If the 787 program was a couple of years late, they'd ship units built later on.

If it was Boeing's shelf, then who replaced the batteries? If Boeing took possession of the units and shelved them, then they'd be responsible for maintenance. Seeing how this was not standard in-service fleet maintenance, who did they send into the warehouse, screwdriver in hand, to swap the batteries?

Given several possible scenarios, this looks like it could be a maintenance procedure problem. Airlines take steps to make sure that work is performed by qualified personnel. because this is a part of their normal business function. But out of sequence manufacturing or maintenance can be a planning headache.

Great point. Say if the ELT were manufactured in 2006, someone might find it prudent to put fresh Lithium batteries in them, since they are supposed to be good for 10 years, before installing them in a plane finished in 2011 or so, so the carrier wouldn't need to turn around in 2016 and replace the battery. Someone unfamilier with the particular ELT, changing the battery, would explain a lot. Honeywell should put a tamper evident seal on there various beacons, and require that, when their battery is 10 years old, the whole unit be swapped with a new one, and the old one sent back, to get a new battery. One of those "No User Serviceable Parts Inside" kind of things. It's for what is sometimes referred to as "Post consumer control of your product". Maybe it's already like that? Maybe someone on the forum knows?

It's probably more complex than this, but, just a thought or two. If the ELT uses a Lithium Magnesium battery, I hope the Magnesium isn't in the same form as was used in "Mag" wheels! Hard to control fires from car wrecks was the reason "Mag" wheels aren't made of Magnesium any longer, but instead are made of Aluminum. . Maybe this type of battery should only be small, for use in low capacity situations, like in smoke detectors, watches, and cameras, so the stored energy isn't enough to burn through routine precautions. I'm sure an alert beacon transmitter would use a lot of current, if it's to transmit for very long, so it probably has a pretty high capacity battery. I've brushed up on my knowledge of different Lithium battery technologies, and it seems like using high capacity ones and/or storing them in close proximity to each other, may be a no no, across the board, until better practices in quality control, design, and use are practiced!

"It's probably more complex than this,"

To be sure. It's MANGANESE, not MAGNESIUM. And it's in a dioxide form, not elemental. :ugh:

ANA finds damaged ELT battery wires
 

Reuters reports:

Magnesium, Manganese, ... What's the difference? Ha, ha ...I didn't know what sort of battery the ELT used, I thought it might have been something like this: Torqeedo 24-Volt Lithium Magnesium Battery : Cabela's
A Lithium Magnesium battery. I thought I'd read, was the battery in Ancient Mariner's picture, but I could be wrong. Anyway, it didn't seem far fetched, that the ELT might use the same type of battery. Of course, the Magnesium, might not be in it's elemental state either, so could be perfectly safe.

What's the difference? Cor, strike a light.....no....on second thoughts don't, or you'll find out! :)

The type of battery (5 ea /pack) should be one of these:

UHR-CR25650-LVP (U10027) - Battery & Energy Products: Commercial | Ultralife Corporation

UHR-CR34610-TSO (U10028, U10029) - Battery & Energy Products: Commercial | Ultralife Corporation

Coagie:
All such relevant, and serious, details have been covered in this thread. You would be best served by keeping up before contributing.

Coagie,

the quoted website also confuses magnesium and manganese: the torqueedo batteries are also Lithium-Mangenese (Mn): This has nothing to do with Magnesium (Mg).

United finds pinched wiring on ELT also
 

United Continental Holdings Inc. ( UAL ) said it has found pinched wiring in one Boeing Co. 787 Emergency Location Transmitter as part of Federal Aviation Administration mandated inspections.
The inspections come in the wake of a fire aboard an empty Ethiopian Airlines 787 at Heathrow Airport on July 12. U.K. Investigators recommended inspections as part of its findings.
A spokeswoman for United said inspections of its fleet of six 787s are now completed and the "defective" transmitter has been sent back to supplier Honeywell International Inc. ( HON ) for evaluation.
The spokeswoman said there was no disruption to United's flight schedule as a result of the inspections.

Bernd, I stand corrected. Thank you. Germans always were good at chemistry. Maybe I should use something other than a Cabela's Outfitters catalog for my research? Anyway, I do stand by my broad brushing of being careful how to use and store higher capacity Lithium batteries. It seems the thermal runaway chance is just too great, to use or store them in anything but a very careful manner! If they are too close together, one bad apple can spoil the bunch. There is some talk of using Magnesium and Sulfur for some kind of electric car batteries. Hope the Magnesium isn't in a dangerous state in that case.

Machaca, Wico! I have read the entire thread, but I got sloppy, and was trying to go by memory, when I should have reviewed the earlier posts. Apologies to all. BTW: Lighten up Machaca, Life is too short.

Guess they need to check the lot number, and see if they are from the same production run, then if so, have all of them pulled, in case the person inspecting didn't have his glasses on. I don't know about Honeywell, and I hope this isn't happening at Honeywell, but in some high tech manufacturers, to save money, when there's an item that doesn't require a constant production, rather than have permanent employees to assemble the item, some companies just wait until they have enough orders to justify a production run, and then hire temporary workers, just for that run. They try to get experienced workers, but it sure opens things up for mistakes. Quite often, the mistakes are "pinched wires" as a matter of fact.

Been lurking quietly and following various aspects of this thread. The above may be an important clue, especially with respect to the ELT. One of the interesting features of teflon insulation (FEP and PTFE) is that in a stressed situation it will slowly do something referred to as 'cold flow'. I first witnessed this about 40 years ago, involving some teflon insulated wire-wrap circuits, on a Univac backplane, where the wires had been pulled too tight against a 90-degree turn, and the teflon insulation eventually cold-flowed to the extent that it made electrical contact with the wire-wrap post that the turn was against. That the battery wire in the ELT appear to have been 'pinched' (based on various sources) and the likelihood that it could be teflon insulated as well, this could be a delayed cold-flow event. The unit was assembled, tested, everything looked good, and then (over time) the pinched insulation flowed back, and a short developed. One possible theory on how this occurred. If so, it is very lucky that the incident happened on an airframe sitting on the stand, with no pax on board.

NASA makes mention of 'cold flow' on this page (right most column, first entry) ...
NASA Parts Selection List (NPSL) - Wire Insulation Selection Guidelines

............

Well, in a submarine perhaps but airplane terms that is not really 'marginal'!

DO160F 'Waterproofness' doesn't even have immersion listed as a test method.

If the ELT is specified by the manufacturer as "Permanently Hermetically Sealed and airtight' (I don't know if that is the case, but I doubt it) then DO160 exempts it from further waterproofness testing, if not then the relevent tests for airplane use will be in DO160 Section 10 and will be selected from four test methods, in increasing order of severity:

'Condensing Water Drip'
'Drip Proof'
'Spray Proof'
'Continuous Stream' (this one is fun - think big pressure washer jet aimed at the most vulnerable joints and connectors!)

The choice of test will be made based on equipment type and it's location in the airplane. I don't know which was selected for the ELT in question.

So to say "787 is to wet for electronics" is clearly inaccurate however there may need to be a review of matching test method to equipment type and location if, and only if, there are repeated and multiple examples of random bits of electronics failing due to water ingress. I don't think we have any facts to show that yet?

Don't confuse occasional poor manufacturing quality with design failings - and before I get jumped on, I accept repeated manufacturing errors can indicate poor design of course.

....such as several occurrences of the same wires getting pinched when a battery that is designed to be replaced in service is fitted for instance....... (This example picked entirely at random you understand!)

o/t
 

.......some of the highest rated exe electrical enclosures use water pressure to ensure their sealing underwater......

Coegie, we've gone away from the "no user serviceable parts inside" , it's a maintenance headache. The older Dukane ULB's (pingers) used to have to go back to the factory for a battery change, the new ones are field replaceable.

What I don't understand is why they are only checking the ones in the '87. Honeywell said there are over 6000 in service. Seems we should be checking them all.
Link to AD http://rgl.faa.gov/Regulatory_and_Gu...2013-15-07.pdf

It does say " This AD is considered to be interim action. Because the fire occurred on a Model 787-8 airplane,required actions in this AD are focused on Honeywell fixed ELTs installed on that model. However,we acknowledge that ELTs are installed on various other aircraft; therefore, continued investigation is required. Once final action has been identified, we might consider further rulemaking. "

ETA: fixed link

Maybe the bad lot was just installed on the 787, but, who knows, it may not just be a bad lot? If there is only 6000 out there, it would be a great idea for Honeywell to issue a service bulletin instructing owners and maintenance crews how to check their ELT's for damage..

SLFgeek,
Am very familiar with this issue from Atlas missile days back in the 60's. Looks like Boeing and Honeywell (who installed the batteries??) forgot their basic materials lessons yet again.

It looks that there are two generations of this ELT classic AFN and new (half sized) AFN2:

http://www51.honeywell.com/aero/comm...U_406_AFN2.pdf

I suppose that the AFN2 is used in 787 but is it spread also in older a/c?

SFL geek and Amicus are correct about cold flow issues, I am just wondering how/why we think we know Honeywell used "thin teflon insulated wire" in the location where the issue occurred?

There was a list of approved wire for the 787, I very much doubt that was on it at all, and if it was it would have been for very specific applications, given it is known to have very poor cut-thru resistance, suffers from cold-flow and is heavy! The only real thing going for it is it's high temperature performance.

Assuming we are talking battery leads, I would expect it more likely that a single or double insulated wire with a polymer such as crosslinked ETFE or PDVF/PVF2 outer sheath would be called out?

Amicus, I too was wondering who actually fitted the batteries, given the production delays it is not beyond the bounds of possibility that the early deliveries of ELT were either without batteries or had them removed to be fitted later and given the focus on only units in 787...makes you wonder?

It could have something to do with battery replacements performed on the units in storage intended for the 787 line.

Normally, I would expect line maintenance to be performed by techs trained and certified to do such work. Including watching for pinched wiring. So the question is: Who did the work on the units stored at Honeywell/Boeing? Perhaps the regulators were already made aware of this maintenance procedure anomaly and decided not to impose additional costs on their other customers.

They may find a single undertrained tech did the battery work on all suspect units. Or the design could be conducive to wire pinching during cover install, without provision for a visual inspection.

These people seem to have an eye on the Ethipian fire and its ongoing aftermath. Analysis: Boeing 787 Dreamliner In the Hot Seat Again After Fire at Heathrow Airport

Update 17: Sunday, July 28 11:15AM E.D.T.

ANA and United Airlines have both found problems with the Honeywell ELT beacons. The issues appears to involve a pinched wire in the emergency locator transmitter. United has completed its inspection of its six 787 fleet, where it located one defective transmitter. ANA also found the same issue in its ELT on 1 example of its fleet and on another uninstalled portable beacon. ANA has removed all beacons from the eight 787s used on domestic routes . JAL completed investigations this weekend on its 9 787s. The FAA and Japan’s transport safety ministry followed suit with the UK’s AAIB in recommending removal or inspection of the ELTs, 2 weeks after the Ethiopian issue. European operators LOT, Thomson, Norwegian Air Shuttle, and British Airways (who is set to debut the 787 September 1st) have removed he ELTs from their aircraft but have not reported damage publicly. This far, no airlines other then Ethiopian obviously have suffered service interruptions as result of the ELT issue, though a Qatar 787 has been grounded on Monday due to an unspecified “minor” technical issue. Boeing has now delivered some 70 787s to its customers, around 20 since the grounding order was lifted in April, including new customers China Southern, Norwegian Air Shuttle, Thomson, and British Airways. These ELT issues are still considered unrelated to the lithium-ion battery defects which caused the worldwide grounding back in January.

Karel_x
 

More than half sized!

Less than half the weight and less than half the batteries needed to power it.

So both units have a 50 hour operating time and a ten year battery life and yet both generate the same 150mW/5W RF output. If the new unit (the 406AFN2) is doing this using only two cells instead of five, then either the circuit losses in the new ELT are more than halved or the battery chemistry in the AFN2 is producing more than twice as much power!

Do we know that the new unit is also using Lithium-Manganese chemistry or are we just assuming it?

Could this fire have been caused by a trapped wire AND a damaged battery with a much higher energy density than its predecessor? We keep hearing that 6000 of these units have been used without incident but how many of the Mark 2 version are in service?

This may not be solely a 787 thing, it may be a problem with the new version of the beacon. :eek:

Eclectic
 

Where do you get your info that all European operators have removed their ELTs?

Speed of Sound
 

A really good question! I would hope that the 6000 figure Honeywell claimed when this started relates to 6000 of the same model as is fitted to the 787, it would be very far from honest of Honeywell to have claimed that if, for example there are 5900 Mk1 and 100 MkII in use and those are all shipped to 787s!

The AAIB Special Bulletin specifically identifies the ELT in question as the RESCU406 AFN (see Safety Recommendation). If the model would be AFN2, don´t you think the AAIB would have said so?

Air Accidents Investigation: Download PDF document

@ Mr @ Spotty M

Click the link I provided.

Question from non-engineer SLF:

What would it cost to design in a supply-rail fuse for the ELT battery? Or failing that, a length of fusible PCB track.

With the glorious benefit of hindsight, a pinched wire seems a rather simple and thus probable error.

John Marsh
 

Initially - practically nothing, retrospectively - quite a lot! (re-design, re-qualification, recall.....)

However, as I said in earlier posts Honeywell have been at this game a very long time, I really can't believe they didn't think of that and the need to protect the cells from shorts 'upstream' of the PCB(s), so the question we are left with is:

What failure mode did the box and it's installation manage to come up with that meant it didn't work?

Very interesting!

I can see the AAIB possibly just referring the unit as its base model name RESCU406AFN but it also refers to it containing a 'set' of batteries rather than a 'pair' and makes reference to '6000 units' which clearly must be the original model.

The first safety recommendation (2013-16) refers specifically to the RESCU406AFN model but the second recommendation (2013-17) refers to "installations of
Lithium-powered Emergency Locator Transmitter systems" which I assume means both mark 1 and mark 2.

http://i1280.photobucket.com/albums/...psbc2f73fc.jpg

For some reason the mark 2 model has the wording RESCU406AFN on the case, which may be the cause of the confusion.

Very strange! :sad: