Ethiopean 787 fire at Heathrow
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, l know of one that is inspecting the wiring around the ELT and the outer case for signs of overheating, on a daily basis.
Remove all fixed ELTs at once.
LeadSled @ #796
Thanks for that(to others; confirming my conjecture that ELTs are useless).
Because ELTs have never saved, and will never save, a single life in heavy transport operations, but cost a lot and introduce risk they should be removed at once.
Prognosis: This will not happen. Regulatory authorities(and manufacturers) will never admit that they stuffed up mightily(just imagine AI admitting that having un-moving thrust levers was a bad idea).
All discussion of battery size, capacity, etc is irrelevant. ELTs must be removed.
Thanks for that(to others; confirming my conjecture that ELTs are useless).
Because ELTs have never saved, and will never save, a single life in heavy transport operations, but cost a lot and introduce risk they should be removed at once.
Prognosis: This will not happen. Regulatory authorities(and manufacturers) will never admit that they stuffed up mightily(just imagine AI admitting that having un-moving thrust levers was a bad idea).
All discussion of battery size, capacity, etc is irrelevant. ELTs must be removed.
Last edited by mangere1957; 31st Jul 2013 at 09:13.
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All discussion of battery size, capacity, etc is irrelevant.
Well the ELT didn't help with finding the Kenyan Airways 737-800 at Douala a few years ago. They were looking miles away when all the time it was in a swamp at the end of the runway.
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ELT's are nor required, according to some folks.
Tell that to all the crew and aircraft found and saved (in some cases) in Canada's North, and elsewhere in NA ! If it had not been for the ELT signal being received for direction to its location, we'd still be looking for an appreciable amount of crashes with the loss of more life.
Signals now include GPS co-ordinates and that speeds up a search.
Unfortunately there are too many misuses of the ELT's causing false alarms and, possibly, delayed reactions.
It seems that some readers and writers on this forum never had their asses over unlandable terrain for a long time !!!
Signals now include GPS co-ordinates and that speeds up a search.
Unfortunately there are too many misuses of the ELT's causing false alarms and, possibly, delayed reactions.
It seems that some readers and writers on this forum never had their asses over unlandable terrain for a long time !!!
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I don't think anybody doubts the value of ELT in General Aviation (specially for VFR flights) but I think they are much less useful for larger air transport aircraft whence for example FAA in the US doesn't mandate them for airliners.
Last edited by olasek; 31st Jul 2013 at 19:16.
Sims Fly Virtually
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Do you remember how difficult it was to track AF447?
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It's the old news axiom dog bites man is not news, man bites dog is news. Frequently hear of various airliners making unscheduled/emergency landing due to cockpit smoke, but they are back page slow news day fillers. Smoke in a 787 overwhelms even the birth of Prince George (naw, even here in a colony fighting to rid themselves of control by another George it overrode everything). But now I read, "Oh, yeah, there have been other ELT fires." To be honest the current alert to travelers resulting from intelligence sources that a terrorist attack planned very soon overrides thoughts of there maybe being an in flight 787 fire or an uncontained A-380 engine explosion that damages much of a wing structure. Scarier yet is seeing the evac photos of people carrying their luggage away from the emergency escape slides. Those are all people who could have blocked my exit and killed me as sure as if they shot me.
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The tlot phlickens re ELT
or in other terms- the fail safe may not have been a fail safe ??
Still seeking cause of 787 fire in U.K. | Business & Technology | The Seattle Times
Still seeking cause of 787 fire in U.K.
As Canada’s Transport Ministry examines Honeywell’s emergency beacons, the company confirms the devices should have been able to prevent overheating in case of a short circuit.
By Dominic Gates
Seattle Times aerospace reporter
The small off-the-shelf electronic device at the center of the investigation of a fire aboard a Boeing 787 Dreamliner at Heathrow airport last month contains a fail-safe mechanism that should have prevented overheating even in the event of a wiring short-circuit, a Honeywell spokesman confirmed Friday.
The Emergency Locator Transmitter (ELT), supplied to Boeing by Honeywell and used in many other aircraft besides the 787, contains a current limiter — a standard feature, like a fuse, that shuts off the current if it gets above a certain level.
Boeing and government investigators inspecting the damaged ELT from the Ethiopian Airlines jet found that internal wires connected to the device’s lithium battery had been trapped and pinched when the cover was reattached as the batteries were inserted.
That led to a theory that the pinching of the wires compromised the insulation, and that crossed wires short-circuited to start the fire.
Honeywell spokesman Steve Brecken said Friday that the ELT contained a current limiter that should have stopped any surge of current caused by a short.
Did the limiter somehow fail? Or was the fire started some other way?
Brecken said all that’s known is that the fire was “in the area” of the ELT and that the investigation led by the U.K’s Air Accidents Investigation Branch is continuing. “We don’t know that the current limiter failed,” he said.
The Wall Street Journal reported Friday that Transport Canada, the aviation regulator in Canada, is preparing to order the inspection of ELTs in all types of planes carrying the device, including Airbus and Dassault.
Last week, Boeing sent out a service bulletin to operators of all its planes — not only the Dreamliner — recommending inspections of the ELTs.
The ELT is manufactured and assembled by a Honeywell subcontractor, Instrumar, of St. John’s, Newfoundland. Instrumar’s main business is technology connected with the production of carpet fiber, and the ELT appears to be its only aerospace product.
Brecken said Instrumar ships the ELTs for the 787 to Honeywell’s Deer Valley facility, near Phoenix, Ariz., and from there they are sent to Boeing.
He said Instrumar ships ELTs for other aircraft and for other manufacturers to Honeywell’s Mississauga facility, outside Toronto.
The Journal said Transport Canada this week inspected the Mississauga facility and will inspect Instrumar’s plant next week.
Still seeking cause of 787 fire in U.K. | Business & Technology | The Seattle Times
Still seeking cause of 787 fire in U.K.
As Canada’s Transport Ministry examines Honeywell’s emergency beacons, the company confirms the devices should have been able to prevent overheating in case of a short circuit.
By Dominic Gates
Seattle Times aerospace reporter
The small off-the-shelf electronic device at the center of the investigation of a fire aboard a Boeing 787 Dreamliner at Heathrow airport last month contains a fail-safe mechanism that should have prevented overheating even in the event of a wiring short-circuit, a Honeywell spokesman confirmed Friday.
The Emergency Locator Transmitter (ELT), supplied to Boeing by Honeywell and used in many other aircraft besides the 787, contains a current limiter — a standard feature, like a fuse, that shuts off the current if it gets above a certain level.
Boeing and government investigators inspecting the damaged ELT from the Ethiopian Airlines jet found that internal wires connected to the device’s lithium battery had been trapped and pinched when the cover was reattached as the batteries were inserted.
That led to a theory that the pinching of the wires compromised the insulation, and that crossed wires short-circuited to start the fire.
Honeywell spokesman Steve Brecken said Friday that the ELT contained a current limiter that should have stopped any surge of current caused by a short.
Did the limiter somehow fail? Or was the fire started some other way?
Brecken said all that’s known is that the fire was “in the area” of the ELT and that the investigation led by the U.K’s Air Accidents Investigation Branch is continuing. “We don’t know that the current limiter failed,” he said.
The Wall Street Journal reported Friday that Transport Canada, the aviation regulator in Canada, is preparing to order the inspection of ELTs in all types of planes carrying the device, including Airbus and Dassault.
Last week, Boeing sent out a service bulletin to operators of all its planes — not only the Dreamliner — recommending inspections of the ELTs.
The ELT is manufactured and assembled by a Honeywell subcontractor, Instrumar, of St. John’s, Newfoundland. Instrumar’s main business is technology connected with the production of carpet fiber, and the ELT appears to be its only aerospace product.
Brecken said Instrumar ships the ELTs for the 787 to Honeywell’s Deer Valley facility, near Phoenix, Ariz., and from there they are sent to Boeing.
He said Instrumar ships ELTs for other aircraft and for other manufacturers to Honeywell’s Mississauga facility, outside Toronto.
The Journal said Transport Canada this week inspected the Mississauga facility and will inspect Instrumar’s plant next week.
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.That led to a theory that the pinching of the wires compromised the insulation, and that crossed wires short-circuited to start the fire.
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I imagine it should not be tough to test this theory, they don't need the whole 787 for that, just a small section of a fuselage with all the relevant tubing/insulation/electrics, etc.
I'm not sure what the 'Current limiter' is, but that is not a description I would use for a 'conventional' fuse so I suspect it is a self-resetting fuse of some sort. These work by increasing their resistance with temperature and that increase in temperature is caused by resistive losses due to the current flow through the device then, as the resistance increases, the current drops or limits.
If the sizing of that device is wrong for the equipment, or the device was faulty, and it is in thermal contact with the battery I could imagine a scenario where it is possible to get a combination of over-current and temperature where the device is cycling 'on and off' (I know it's not quite on and off but you get the idea) and the combination of a hot day, hot limiting device and self-heating in the battery due to the fault current could be, over time, that the Li battery is heated to the point of thermal runaway.
How's that for speculation from someone who doesn't speculate?
N4790P
It can’t be coincidental the Honeywell are one of the worst OEMs to deal with in just about every aspect and every division.
Whether it’s APUs, Avionics, spares, repairs, rip off pricing policies, general support issues such as updating EGPWS, there are a myriad of issues. These issues are spread across the complete aviation community too. Absolutely nothing to do with Boeing.
These aren’t new issues and maybe, just maybe they are indicative of cultural issues within a corporation that has lost its way?
Whether it’s APUs, Avionics, spares, repairs, rip off pricing policies, general support issues such as updating EGPWS, there are a myriad of issues. These issues are spread across the complete aviation community too. Absolutely nothing to do with Boeing.
These aren’t new issues and maybe, just maybe they are indicative of cultural issues within a corporation that has lost its way?
Last edited by ZFT; 3rd Aug 2013 at 09:50.
The Emergency Locator Transmitter (ELT), supplied to Boeing by Honeywell and used in many other aircraft besides the 787, contains a current limiter — a standard feature, like a fuse, that shuts off the current if it gets above a certain level.
Which raises another interesting issue: If the original Honeywell batteries were replaced (and they incorporated said limiter), were they replaced with OEM batteries? Or is there a generic 'equivalent' that may have been substituted?
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Not even that, all that is needed initially is an ELT
Last edited by olasek; 3rd Aug 2013 at 18:39.
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EEngr
There is no way anything other than a Honeywell part could be used and maintain certification I would hope?
As you point out, the polyfuse (or whatever) must be part of the battery pack to be any use, hence my thought about it being in close thermal contact with the cells - perhaps deliberately in the hope that it would shut things down if the cells got to hot? Wouldn't be any use in a thermal runaway situation though.
As you point out, the polyfuse (or whatever) must be part of the battery pack to be any use, hence my thought about it being in close thermal contact with the cells - perhaps deliberately in the hope that it would shut things down if the cells got to hot? Wouldn't be any use in a thermal runaway situation though.
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olasek
at some point they better get more aircraft structure to replicate the overall damage, fire propagation, etc.
Hmmmm....Sorry "in the light of" might be an unfortunate phrase to use in the circumstances......
Last edited by fenland787; 3rd Aug 2013 at 19:03.
I cannot speak for the particular cell pack in the ELT but having dismantled and rebuilt quite a number used outside aviation it is standard to include a fuse or a polyfuse (effectively a self resetting fuse) in a pack. These often turn up as links between the actual cells of multi cell batteries but on single cell designs they are at the cell ends of the leads or on an attached protection circuit board.
Whoever did that design would have been expected to test their design (i.e. apply both increasing and random levels of excess discharge current and finally an immediate short circuit across the battery terminals or wires) to ensure the battery shut down and stayed shut down safely in each case.
From the reports the two leads were shorted together which should have resulted in a very short pulse of current then a drop to a hugely limited current for the duration of the fault thanks to the action of the polyfuse. If the polyfuse failed to work or failed to reduce the fault current enough for safety the cells would then be able to potentially overheat over time running the risk of Cell thermal runaway. If the short circuit was intermittent this might have been the subject of many repeated cycles of short, shutdown and recovery and perhaps this is where the issue arose
Once the cells reach a critical internal temperature (c 135c IIRC) they proceed to break down and self ignite and no fuse is going to help them after that point
Whoever did that design would have been expected to test their design (i.e. apply both increasing and random levels of excess discharge current and finally an immediate short circuit across the battery terminals or wires) to ensure the battery shut down and stayed shut down safely in each case.
From the reports the two leads were shorted together which should have resulted in a very short pulse of current then a drop to a hugely limited current for the duration of the fault thanks to the action of the polyfuse. If the polyfuse failed to work or failed to reduce the fault current enough for safety the cells would then be able to potentially overheat over time running the risk of Cell thermal runaway. If the short circuit was intermittent this might have been the subject of many repeated cycles of short, shutdown and recovery and perhaps this is where the issue arose
Once the cells reach a critical internal temperature (c 135c IIRC) they proceed to break down and self ignite and no fuse is going to help them after that point
