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back to article UK investigators finger emergency beacon for 787 Heathrow fire

The initial accident report into the Boeing 787 that caught fire at London's Heathrow airport last week has concluded that the fault likely lies with the aircraft's emergency location beacon, and it recommends disconnecting it as an interim measure. The world's third-busiest airport was shut down for over an hour on Friday after …

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Won't be told

Said it before - lithium batteries are too cranky for aeroplanes (especially plastic aeroplanes). Burning a hole in your trousers is unpleasant, burning a hole in an aeroplane is a disaster.

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Mushroom

Re: Won't be told

Please RTFR, lithium manganese dioxide batteries are worlds away from lithium ion and lithium polymer batteries...

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Meh

Lets hope

That when one crashes a survivor will be able to use his mobile phone to call the emergency services!

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Anonymous Coward

Re: Lets hope

So long as they don't rely on Apple Maps for their location that is.

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Anonymous Coward

Re: Won't be told

Correct, we use lithium batteries down oil wells, where it is notoriously hot and unpleasant. They don't just explode for no reason.

We have a lot of problems with this airplane because of the wiring.

Wiring is a bugger like that. You can spend all day designing the best widget in the world, but get the wiring wrong and it's screwed anyway. You have no idea how many electronics issues can be traced back to it.

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Re: Won't be told

I think that is overly harsh.

Lithium batteries can be used, but the cooling requirements of a carbon fibre aircraft are making a bit of a difference.

The old 'well its always worked before' approach is not it seems working now.

It will get solved, BUT not before Boeing has taken a big commercial hit.

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Re: Won't be told

No they are fairly similar.

Better, but still liable to burst into flames at elevated temperatures. And still able to easily destroy themselves and start a fire when shorted.

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Re: Won't be told

have you any idea how hot an aircraft skin, parked in full sun, gets...a LOT hotter than down a mine or well.

Especially if its made of carbon fibre..

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Anonymous Coward

Re: Won't be told

Then something needs to be done. Although carbon fibres can take pretty high temperatures, the polymers that hold them together cannot.

The reason that glass fibre boats are painted white is because otherwise in the tropics the hulls could overheat and delaminate. Polyester, vinylester and most epoxies are not really Lloyds certifiable because they are not boilproof, whereas things made of resorcinol glued wood are.

I doubt that the skin gets hotter than it can get down an oilwell. But I'm prepared for someone to tell me I'm wrong, and cite numbers.

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Facepalm

Wait

... they're disabling an emergency beacon? Really?

Given its function, it seems to be the kind of stuff you really want to have if the airplane ever crashes! Wouldn't it be better to fit a non-flamey version of the beacon instead of leaving the airplane beaconless?!?!

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Re: Wait

Certainly, but they might not have a non-flamey version lying on the shelf. Different device, likely different shape and so on. So that's the solution you want to work towards, but not an immediate one.

Until then the question becomes, which is the greater risk: the aircraft crashing and rescue being hindered by absence of an ELT, or the aircraft catching fire by the presence of one. Note that on-board fire-fighting kit proved insufficient to the task -- you really don't want this happening in flight. Give the rarity of crashes, reducing the risk of fire is almost certainly the smarter choice.

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Re: Wait

The aircraft still has emergency beacons, the ELT is just more accurate than the others. A typical passenger aircraft will have 3 small beacons: 1 in the nose section, another right between the wings, just under the deck plating and one in the tail assembly, some of the bigger planes have more or attached as optional components depending on purpose of the craft.

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Boffin

"likely different shape and so on"

But that's what Duct Tape is for.

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Devil

Re: Wait

I do not see a problem with it - provided that its FAA certification is adjusted accordingly. I do not see how on earth, in hell or otherwise an aircraft which does not have a functioning beacon can have 270 minutes divert allowance (that certification without an operating record was insane in the first place). With a non-functioning beacon it should not be allowed the normal 60 which nearly all two engine aircraft have as it is.

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Joke

Re: that's what Duct Tape is for.

Just make sure to use the roll that comes with round things. The ones that tear off in rectangular brackets will suffer too much stress.

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Anonymous Coward

Re: "likely different shape and so on"

It's Duck Tape. No, really. It may get used for taping ducts, but the original inventor still sells it as Duck Tape.

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Re: "likely different shape and so on"

The dutch word 'doek' is the origin here and when used with tape it refers to adhesive tape made from or strengthened by cloth. Hence duck tape and Duck (R) tape. Some jurisdictions don't allow it to be used on ducts unless it is specially treated.

http://en.wikipedia.org/wiki/Cotton_duck

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Boeing was minding his business...

Farmer Boeing was riding on his ass, making his way slowly towards the village market, ogling the buxom farm girls in their colourful dresses, when a strange, unsettling and brittle worm-like creature appeared out of the blue and bit him for no apparent reason.

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Alert

Plastic Vs Aluminium

Surely ANY fire or risk of fire is worse in this plane than the older ones. Surely it needs higher standard wiring and LOWER fire risk design parts.

Was too much outsourced and cost reduced?

How do you make brittle Teflon (PTFE). That's an achievement.

Also other than Glass or Ceramic or Fibre glass about the most fire proof cable insulation*. Used since WWII for expensive wiring.

*You can burn it, but it needs a lot more heat than say PVC.

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Anonymous Coward

Re: Plastic Vs Aluminium

I see you've got a downvote already. Some explanation from the downvoter would be welcome.

Is it my imagination or do I remember PTFE wirewrap (and other) wire in the 1980s? IE It's not exactly new (WW II even before that!), and you would hope that by now its characteristics should be widely understood. I

Whereas the characteristics of composite fuselages, in the unseasonal London sun for 8 hours with no electricity to power the aircon, therefore getting hotter by the hour in the higher parts of the fuselage (heat rises, etc).. no, surely nothing that simple... surely please?

"Was too much outsourced and cost reduced?"

Maybe the downvote means somebody doesn't want that question asked or answered? Some of us already have our opinions.

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Joke

How do you make brittle Teflon (PTFE). That's an achievement.

That'll never stick.

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Alert

Re: Plastic Vs Aluminium

PLEASE someone tell me this whole wiring story is not true. :-(

For all the self-professed techies around here, I guess it is apparent that most have no interest in aviation technology. Brittle wire? To learn what it can do Google "Kapton", and then "Kapton Swiss Air", and learn the horrors.

Yes, you can indeed make" brittle" PTFE coatings - the PTFE is combined with other ingredients in hopes to gain additional advantages. PTFE might be flexible in native state but it has other problems - it does not have the utmost in abrasion resistance and, even worse (from an aviation perspective) according to Wiki's tech article, it degrades over time with exposure to temperatures over 79 C / 117 F. If you think that those temperatures are never reached in an aircraft, I would advise you to study NTSB's TWA Flight 800 technical briefing at http://www.ntsb.gov/doclib/reports/2000/AAR0003.pdf and hit section 1.16.5.1 starting at page 124 / PDF page 142 :o

Anyway, the EXACT quotation from the source material story regarding the Teflon wiring is:

"To my amazement, I have been told by someone in the know, that the Teflon insulated wire being used on the Dreamliner is so fragile (emphasis mine), mechanics are prone to saying, "Don't look at it too hard or you'll break it." Teflon insulated wiring helped save weight for an airplane Boeing billed as 20% more fuel efficient."

This may be the EXACT the same failing of Kapton - in this case, the PTFE insulation may have been made so thin, in the name of weight savings, that it simply cannot stand up to the physical abrasion / heat-cool cycles that an airliner places on it. The suspected cause of Swissair 111 was Kapton abrasion and this lack of abrasion resistance was what led to Kapton being BANNED by the U.S. Navy and the FAA ended up issuing numerous AD's (Airworthiness Directives, the highest level of 'recall' notice) to cover it. Millions of dollars were spent after Swissair 111 in rewiring aircraft to get rid of Kapton in various systems due to lack of durability and if they have created the same situation in the new PTFE wiring, in the name of weight savings, we are in for serious trouble.

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in the unseasonal London sun for 8 hours

Whereas in Ethiopian Airlines home country it's never exposed to those kind of temperatures...

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Mushroom

Re: Plastic Vs Aluminium

And making additions to that extruded PTFE would be for what reason? As an actual *materials* engineer, not the idiot mechanical engineers we spend all day fixing the screwups of and who are responsible for this 'PTFE is too brittle' nonsense, PTFE extruded insulation is used because of its fireretardence and excellent environmental and electrical performance. PTFE does exist as a *bulk* engineering polymer with lots of different additions, but no-one on earth is going to try to extrude Glacier DU around a gorram piece of nickel-plated copper wire. The reference in WIki is bunk. PTFE has a continuous upper working temperature of about 150 degrees. That's continuous as in, forever.

And, really? Brininging kapton into the conversation to muddy the waters? Kapton is polyimide, a thermosetting polymer not a thermoplastic, with entirely different set of chemical mechanical and environmental properties for PTFE. This is nothing like the issues with kapton insulation, thank you very much.

*Seethes at the general ignorance*

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Pint

Re: Dammit Falanx!

You made me learn something!

On a Friday as well!

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Anonymous Coward

Re: in the unseasonal London sun for 8 hours

"Whereas in Ethiopian Airlines home country it's never exposed to those kind of temperatures..."

Stop and think for a moment. Just a moment.

Any of the experts reading here know what Standard Operating Practice for ground power is in sunnier climes than LHR?

Maybe routinely leave the aircraft with ground power active, maybe to run a bit of ventilation, maybe even run a bit of cooling? Would seem sensible to me, although Skippy doesn't seem to think so.

In the LHR incident the ground power was switched off, the aircraft was shut down, including the ventilation and aircon. In the hot sun, unventilated aircraft get hotter by the hour till they reach equilibrium, just like unventilated cars and vans, except bigger and hotter.

In an aluminium skinned aircraft you've got decent thermal conductivity. Significant hotspots aren't that likely.

Who knows about the thermal conductivity of the Plastic Padding used on this aircraft, or about SOP in sunnier climes?

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Re: Plastic Vs Aluminium

"Whereas the characteristics of composite fuselages, in the unseasonal London sun for 8 hours with no electricity to power the aircon, therefore getting hotter by the hour in the higher parts of the fuselage (heat rises, etc)"

And according to a poster at PPRuNE (Professional Pilots' Rumour Network) who seems to know his stuff, there is inadequate (read "no") fire-retardant material in the top half of the fuselage on the 787 (see postings by amicus at http://www.pprune.org/rumours-news/518971-ethiopean-787-fire-heathrow-20.html). He also writes that the resin used will ignite at about 550 degrees F (288deg C), and that it is the same stuff that got banned for use on oil-rigs after Piper Alpha. Just to add to the fun, he reckons that a fire that burns through the skin whilst in flight will tend to propagate in the air-flow rather than extinguish (like a blown-on cigarette end, as I imagine it). Now, I don't have the technical expertise in composites to evaluate all this, but it makes me rather worried about this particular aircraft if even part of it is true! Now add a new type of wiring that is brittle, and I think I'll be avoiding it for a considerable time.

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Re: Plastic Vs Aluminium

Yerrs, what you say is true BUT we have a situation in which a battery has exploded and an aircraft has caught fire. Iether te barrety did that all by itself because it was flaming hot, in which case its either something about the CF that is causing hugely elevated temps, or ots something about the wiring.

As far as parking aircraft in Ethiopia, the dreamliner hasn't been parked in Ethiopia yet.

That beacon goes into dozens of other aircraft. They don't routinely catch fire. Ergo there is something specific about the aircraft installation.

One of the things in that aircraft, is that its using low weight wiring. Its too soon to say, but that is at least a likley candidate for further investigation. As is temperature monitoring of a parked aircraft to see just how hot it really is getting.

I would not be surprised to see temperatures approaching 180C at or near the CF surface. It is a great absorber of sunlight., And a coat of white paint is not as good as being a reflective metallic surface.

These are all soluble issues, but until they are solved, its not looking good for this plane.

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Anonymous Coward

Re: Plastic Vs Aluminium

"That beacon .. don't routinely catch fire." : Yes, something is very likely different here.

"the dreamliner hasn't been parked in Ethiopia yet" : I didn't know that, and probably most other readers didn't either. Including SkippyBing, apparently.

"temperature monitoring of a parked aircraft to see just how hot it really is getting." :Surely they've already done this? Please?

The bit that particularly bothers me is the combination of large quantities of niche materials, in relatively new applications, combined with old operating practices, e.g. if you KNOW it's going to be hot, maybe you leave the ventilation on, but London isn't hot, therefore switching ground power off is OK. After all, that works for all other aircraft in London in the past doesn't it, and nothing's new and untested here is it?

" low weight wiring .. likley candidate for further investigation" : Yes. Afaict the only wiring from the ELT to the airframe is low power wiring, for something like a "test" button in the cockpit. Not power wiring. We'll see.

"These are all soluble issues, but until they are solved, its not looking good for this plane." : Not good also for the people who have approved it for commercial flight, seemingly on the basis of little more than all the suppliers promising that everything would be OK (an exaggeration perhaps, but how much?).

We wait and see.

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Anonymous Coward

Re: Plastic Vs Aluminium

If you think Wikipedia is a poor primary source, until you've seen PPRunNE you ain't seen nothing, son.

Not too long ago, one contributor wrote in regard to a fairly minor light plane incident that "He could not rule out alien involvement" and he was absolutely dead serious.

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Anonymous Coward

Re: Plastic Vs Aluminium

Wikipedia and PPrune are both mixed bags. Some rubbish (aliens, and for this incident the "no reason to close LHR completely" meme), and some sources of definitive information (links to legit Boeing and other documents about what's where on this aircraft) and some sources for further research which outsiders may not otherwise have known about (e.g. Piper Alpha should hopefully be well researched and documented, though how much of it is readily available on t'Interweb is moot given that we're talking late 1980s).

PPrune has now caught on to the "parked in a sunny place" discussion but as yet no one's asked whether the standard operating procedure in sunny places includes forced ventilation/cooling, and whether ground power (which was off at LHR) is needed for forced ventilation/cooling.

Much of amicus's stuff is detailed technical stuff in his own particular field, which most of us won't be able to comment on let alone benefit from.

One very valid point he makes should be understandable by most folk here [paraphrased]:

"In an aircraft with a relatively short history (less than two years of flying and not many total hours in the air), there have already been three fuselage fires. What should that be telling us?" [paraphrase ends]

Isn't that a fair question?

Does anyone at Boeing HQ remember the Ford Pinto fuel tank story, or isn't that story fashionable on MBA courses?

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Re: He could not rule out alien involvement

To be fair - he couldn't

I think this is going to be my new favourite phrase for bug reports

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Anonymous Coward

Re: Plastic Vs Aluminium

The dreamliner is trying to be more fuel efficient, hence weight reductions. But this is moving into uncharted territory as a result.

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Anonymous Coward

Re: Plastic Vs Aluminium

We used PTFE clad wire in the late 1970s. It was for tropicalised equipment being sent to India, where the cockroaches eat PVC. (I am not making this up).

I find it hard to believe that it could get brittle so quickly; it had a lot more elongation than PVC. The insulation only needs to be quite thin and so the wire is very light, but the weight saving on a two tonne machine tool really was not significant. It cost a lot more, though. I remember being phoned up by the foreman at BICC to ask whether we wanted the marking on the earth wire straight or twisted, because he hadn't got the original order and if they made the wrong one there was virtually no chance of selling it to anyone else.

I could be persuaded to believe that the thin insulation makes it more prone to wear through due to vibration.

Also, unpleasant as the fumes from hot PVC may be, the fumes from overheated PTFE are much, much worse. Fluorine is one of the nastiest substances out, up there with mercury. You may survive inhaling hydrogen chloride, but fluorine gas is more or less guaranteed death.

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Re: Plastic Vs Aluminium

Insulation - we don't need no insulation. This is an American aircraft, post-and-wire was good enough for our houses it should be good enough for airplanes (*)

(note: come the counter-revolution this word will be banned)

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Anonymous Coward

Re: Plastic Vs Aluminium

Upvoted for supplying information in a digestible format. I join you in your seethe. Anyone who doesn't know the difference between kapton and ptfe really shouldn't be posting on this forum, especially if they actually have responsibility for any wiring in difficult conditions.

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Anonymous Coward

Re: Plastic Vs Aluminium

Even mentioning Ford in the same sentence as Boeing is an insult to Boeing engineers. And I say that as someone who hopes Airbus crushes Boeing's nuts (big local employer).

But you are right about one thing. Like the Library in the Borges story, Wikipedia contains both truth and falsehood. As a result, it's impossible to use it except as a lookup for subjects you actually already know about, which rather defeats the purpose.

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Re: Plastic Vs Aluminium

Apparently I should be more explicit when I make my points.

Is a slightly warm London the warmest conditions a 787 will have been parked in? I doubt it, ANA uses them and last time I was there Tokyo was pretty warm as well. Shockingly airline manufacturers heat and cold soak their aircraft as part of the design and certification process.

Will there be procedures for parking in warm weather? Probably if it's thought it could be an issue, if not it's likely adverse reactions would have occurred somewhere else first as a seasonally warm London is quite mild compared to a lot of places.

Will these procedures list the airport they should be carried out at? I doubt it, they'd probably use something more reliable like the air temperature. If only there was some way of getting that at an airport...

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Anonymous Coward

@ itzman

"As far as parking aircraft in Ethiopia, the dreamliner hasn't been parked in Ethiopia yet."

Where did that come from ?

AAIB - landed at LHR...... after an uneventful flight from Addis Ababa

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Boffin

Re: Plastic Vs Aluminium

Theatrical lights use what I believe to be teflon wire to the sockets, where it gets quite hot. The jacket on this wire is tough. It's been in use in the theatres I work in for over 20 years, and I would never describe it as brittle. Quite the opposite.

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Anonymous Coward

Re: Plastic Vs Aluminium

Forget the PTFE, the really worrying bit is "the French company Labinal, which specializes in electrical wiring used in the 787".

French electrics? In an airplane? They've never heard of Renault?

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Given the choice of flying on an aluminium or composite plane, I'll go for the aluminium. As we all know, early adopters are exposed to all the undiscovered faults.

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"Early adopters"? This stuff's been flying around in aircraft primary structure for well over 30 years. The fact that it's only now appearing in large portions of commercial airliners is down to its reducing cost and the caution of the aerospace industry, not a lack of experience.

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@Duffy Moon

I agree, new is dangerous. New cars are recalled too and yesterday yet an other Dremliner had to return mid flight. As for "bite Boeing on the ass". I am more concerned with my own. And as for the DC10 it was the cargo doors that opened mid flight and too down two or three planes. That was a stupid design error with the incentive of giving slightly more room in the cargo space..

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now appearing in large portions ..

..is the key.

if the whole skin is now CF, thats a BIG area to absorb sunlight, and not be especially good at radiating internal heat away

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Unhappy

Re: @Duffy Moon

And as for the DC10 it was the cargo doors that opened mid flight and too down two or three planes.

Starter for 10: Which aircraft manufacturer was it who continued to install non-plug cargo doors and fit a similarly risibly inadequate safety interlock mechanism, some time after the DC10 failures? When said manufacturer was appraised of the inadequate locking system, did they a) ground the affected aircraft to fix the problem or b) shove their heads up their arses until 9 people died when a door let go and took a big chunk of fuselage, along with a few rows of seats, with it?

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>I'll go for the aluminium. As we all know, early adopters are exposed to all the undiscovered faults.

I'm sticking with wood

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If it ain't Boeing...

...it ain't burning....

Given that these planes seem to catch fire at the drop of a hat, I wonder how easy and.or costly it is to repair heat-damaged composite?

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Happy

Re: If it ain't Boeing...

"...it ain't burning...."

That's a bit unfair.

Besides "Screamliner" is better.

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