Ethiopean 787 fire at Heathrow
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Hmmm
they seem to be eeping a pretty good track of events
Another important passage is:
Using insulated FRPs to repair concrete means that after a fire, it may be possible to replace the FRP system – the FRP and insulation – rather than replace the reinforced concrete member.
Given the likely temperature that the fuselage burned at, it is a testament to the strength of the CFRP outer skin that the amount of damage on the 787 was relatively limited.
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Thanks green granite and ionagh.
So basically data connections then. These will eventually terminate at the pins on an IC inside the unit and if wired incorrectly will most likely 'confuse' the logic of the processor but unlikely to cause a short circuit to the battery pack.
Given the almost faultless history of this device, installation/location of this device may be where the AAIB should be concentrating their efforts.
So basically data connections then. These will eventually terminate at the pins on an IC inside the unit and if wired incorrectly will most likely 'confuse' the logic of the processor but unlikely to cause a short circuit to the battery pack.
Given the almost faultless history of this device, installation/location of this device may be where the AAIB should be concentrating their efforts.
Other than putting all ELT's in the bin, as some Aussies seem to suggest, maybe one could return the ELT to the condition of entirely isolated from all of the aircraft elecrical systems.
This is NOT what Australian regulations are suggesting. Indeed, Australian regulations require most aircraft, on all but very short flights, (some Ultralights are exempt) to carry an ELT.
What is NOT required is a fixed ELT, for the reasons so comprehensively demonstrated by REAL WORLD results, not theoretical claims about design performance real crash loads, not "designer" crashes.
What is the point of carrying a device that has a failure rate of around 95% (100% in water) AND THIS RESULT INCLUDES LARGE AIRLINE AIRCRAFT not just small GA aircraft.
Quite a number of posters here discuss the merits of a fixed ELT in a way that suggests that the device is actually going to perform some useful function, in the event of a crash. The figures are very clear, the likelihood of any useful broadcast is extremely remote.
In the case of the recent crash at KSFO, I think I am on safe ground in saying that the fixed ELT there in the B-777 (if one was fitted) would not have broadcast a useable signal.
The failure reasons are really quite simple, in the crash sequence, in most cases, either or both the aerial cable or the external aerial are damaged. Although less common, failure of the G switch to activate have been recorded, in circumstance where the calculated G load were such that the system should have worked.
The bottom line here is quite clear, as far as any safety contribution is concerned, fixed ELT are a waste of money and add an extra potential failure mode with on-board fire as a result.
Portable ELTs, on the other hand, have a well established record of producing some quite amazing results, even under the old pre-GPS 121.5/243 COSPAR/SARSAT system, in leading searches straight to the wreck, without even a box search being necessary.
The US Civil Air Patrol, as a result of the Australian research, did a study and found, within the limits of the available data, substantially similar result -- which should surprise no one who has ever spent any time at an aircraft accident site.
None of the airline aircraft I ever flew were fitted with fixed ELT and that never stopped them flying in FAA airspace they were all fitted with with multiple portable ELT, in many cases with a water activated power source, so if it was a survivable land accident, a few blokes were going to have to pee in the plastic bag tied to the ELT for just that purpose. In a ditching, no shortage of "activating fluid".
I have actually had a commercial Li AA size and a 9V NiCad battery have a thermal runaway, in each case the manufacturer said it was impossible. Any exothermic chemical reaction which runs away caused by who knows what ? Impurities acting as an unintended catalyst ? The 9V case was interesting, the multimeter case felt warm, I removed the battery, and it continued to get hotter in my hand until I could no longer hold it so I put it on a bench and watched it finally burnt it all took about 15 minutes from the time the battery was removed from any potential short circuit. A short was unlikely, as the multimeter worked OK when another battery was fitted.
Last edited by LeadSled; 19th Jul 2013 at 08:47.
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All the known issues relating to the entire electrical and battery system worry me, especially as the wiring is apparently not covered in the usual type of insulation, but an ultra thin coating of Teflon. Teflon is an amazing material, but not good at resisting abrasion. A problem on the coating over aluminium wire in a damp un-insulated area of the plane near the skin could be part of the problem. I will not be surprised if the wiring eventually has to be replaced.
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The Japan Airlines flight from Boston to Tokyo turned back as a "standard precautionary measure" around five hours after taking off, according to a company spokeswoman.
Pilots landed the plane safely after a maintenance warning indicated a possible fault.
Pilots landed the plane safely after a maintenance warning indicated a possible fault.
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So basically data connections then. These will eventually terminate at the pins on an IC inside the unit and if wired incorrectly will most likely 'confuse' the logic of the processor but unlikely to cause a short circuit to the battery pack.
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As an engineer in a completely different industry, I often refer to air crash investigations as an example of how to learn from mistakes and improve the product.
One thing that has always impressed me is that AAIB reports are written in clear English with any jargon and acronyms explained, so those not involved in the aviation industry can understand them.
It's a bit of a surprise then, that the first recommendation of the report is ....initiate action for making inert.....
This has been reported in the media as 'switching off' which is plainly the wrong interpretation.
As it is unknown if the fault was internal or external to the battery pack, would it not have been better to recommend removal of the ELT or the ELT battery?
Does 'making inert' offer other options, like encasing the battery pack in a metal box, and surrounding it with a flame suppressant material?
One thing that has always impressed me is that AAIB reports are written in clear English with any jargon and acronyms explained, so those not involved in the aviation industry can understand them.
It's a bit of a surprise then, that the first recommendation of the report is ....initiate action for making inert.....
This has been reported in the media as 'switching off' which is plainly the wrong interpretation.
As it is unknown if the fault was internal or external to the battery pack, would it not have been better to recommend removal of the ELT or the ELT battery?
Does 'making inert' offer other options, like encasing the battery pack in a metal box, and surrounding it with a flame suppressant material?
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Does 'making inert' offer other options, like encasing the battery pack in a metal box, and surrounding it with a flame suppressant material
Seriously I think the investigators know that wrongly calling "Lithium Battery" as the problem would be a PR disaster so they are careful to call it as an internal OR external issue. Not least as they are probably still uncertain of precisely what DID happen. Remember they spent months not finding conclusive evidence of what caused the main batteries to self destruct even with several to examine
I suspect the "Inert" wording is intended to convey "Make harmless" and thereby encourage the fullest practical set of Battery removal, Cable disconnection and removal/isolation actions
I suspect the "Inert" wording is intended to convey "Make harmless" and thereby encourage the fullest practical set of Battery removal, Cable disconnection and removal/isolation actions
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similar to the jal disaster with the botched up 747
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I remember watching the TV documentary about the 777, ("21st Century Jet"?) and was surprised that the plane and engines were to be fully designed on computer and not need testing.
One older engineer insisted that an engine SHOULD be tested for real on a plane and possibly, because of the presence of cameras, the then boss Mullally finally agreed to test fly an engine on an existing plane. As it banked slightly just after take-off there was a compressor stall, and it transpired that the programmers had forgotten to consider Gravity!
I have now learned that rather than strengthen ties between management and engineering, Boeing has separated the two even further by moving management to Chicago, hundreds of miles away.
This division of management from production, then issuing unrealistic demands and deadlines to the "dirty end of the company" is sadly all too common in industry and commerce these days and I feel it is a deeply flawed business model, and one which may be partly responsible for delays and problems with the 787.
We saw this so clearly in UK when companies such as the railways and Water Boards were privatised: engineering staff were rapidly chucked off the management team and side-lined. They were replaced by Business studies graduates with little or no understanding of the dirty end, who soon cut back on maintenance staff and procedures, and a string of serious and fatal accidents soon started.
One older engineer insisted that an engine SHOULD be tested for real on a plane and possibly, because of the presence of cameras, the then boss Mullally finally agreed to test fly an engine on an existing plane. As it banked slightly just after take-off there was a compressor stall, and it transpired that the programmers had forgotten to consider Gravity!
I have now learned that rather than strengthen ties between management and engineering, Boeing has separated the two even further by moving management to Chicago, hundreds of miles away.
This division of management from production, then issuing unrealistic demands and deadlines to the "dirty end of the company" is sadly all too common in industry and commerce these days and I feel it is a deeply flawed business model, and one which may be partly responsible for delays and problems with the 787.
We saw this so clearly in UK when companies such as the railways and Water Boards were privatised: engineering staff were rapidly chucked off the management team and side-lined. They were replaced by Business studies graduates with little or no understanding of the dirty end, who soon cut back on maintenance staff and procedures, and a string of serious and fatal accidents soon started.
ELT removal consequences
There is one aspect which, to my knowledge hasn't been mentioned so far.
The AAIB appear to be recommending that the ELT is removed or disabled, at least on the other 787s. But in the AF447 disaster the ELT might have allowed the aircraft to be found sooner, had the batteries lasted longer. In fact IIRC there was a recommendation in the BEA final report that ELTs be fitted with batteries of longer endurance to give searching teams more time to locate an aircraft (worst case at the bottom of the ocean).
I appreciate that it was a different aircraft type, but surely the principle is the same. I imagine that if AF447 had never happened no one would be particularly concerned whether or not the ELT was fitted or working, but of course this isn't the case now.
The AAIB appear to be recommending that the ELT is removed or disabled, at least on the other 787s. But in the AF447 disaster the ELT might have allowed the aircraft to be found sooner, had the batteries lasted longer. In fact IIRC there was a recommendation in the BEA final report that ELTs be fitted with batteries of longer endurance to give searching teams more time to locate an aircraft (worst case at the bottom of the ocean).
I appreciate that it was a different aircraft type, but surely the principle is the same. I imagine that if AF447 had never happened no one would be particularly concerned whether or not the ELT was fitted or working, but of course this isn't the case now.
Last edited by SRMman; 19th Jul 2013 at 10:26.
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.....But in the AF447 disaster the ELT might have allowed the aircraft to be found sooner, ....
I think the FDRs have a sonar type transducer 'pinging' away to allow location underwater but I don't thing the standard ELT does?
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My interpretation of these words is that the ELT is a suspect but is far from being confirmed as the guilty party. In simple terms, the guy was there, he had a gun, but we can't find any bullets.
An aluminum body would have safely grounded the energy around the skin.
the composite body allowed it through and into the ELT, setting it on fire.
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ELT
ELT like the one fitted on the ET B787 is an option. Many airlines do not have it. In my airline none of the B777 or early Airbus have it. So it makes little difference if you remove all the units fitted to B787. Mind you there are more portable units on aircraft located in the cabin that can be manually deployed. There are also a couple of units on the door slide raft. These are cylindrical in shape. I think the ones fitted to AF flight was one of these units. These are accessible to cabin crew in case they have a run away battery.
Another question if some one can answer. We hear that the fuselage skin of this ET aircraft is not holed as most of us concluded from the video grab. This is as per the AAIB. They have mentioned severe damage to about 8 feet of the skin. The smoke was first noticed by ATC who initiated the emergency action. If all the doors were closed, how did they notice the smoke? From a vent?
Another question if some one can answer. We hear that the fuselage skin of this ET aircraft is not holed as most of us concluded from the video grab. This is as per the AAIB. They have mentioned severe damage to about 8 feet of the skin. The smoke was first noticed by ATC who initiated the emergency action. If all the doors were closed, how did they notice the smoke? From a vent?
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although a rapid descent knowing that the composite roof section was burning through just in front of the tail, would worry me a bit.
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lightning strike.
An aluminum body would have safely grounded the energy around the skin.
the composite body allowed it through and into the ELT, setting it on fire.
An aluminum body would have safely grounded the energy around the skin.
the composite body allowed it through and into the ELT, setting it on fire.
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Speed of Sound
SoS
I have been having the same thoughts, as I 'believe' that ET do not have the rear crew rest areas installed on the 787 at the rear, so straight away there would be differences from standard production types.
I am presuming that all of the original services that would have fed into this rest area would still be roughly in that location, albeit disconnected and (hopefully) all safely capped off and secured. The internal finishes and fittings would therefore also be nonstandard in this area. So could this combination cause some kind of detrimental enviromental change in the area where the ELT is located?
Given the number of ELT's in use its either the ulimate s*ds law that this has happened on a 787, or is there something specific about this ET version?
Is it known if there are any other operators using this configuration?
Given the almost faultless history of this device, installation/location of this device may be where the AAIB should be concentrating their efforts.
I am presuming that all of the original services that would have fed into this rest area would still be roughly in that location, albeit disconnected and (hopefully) all safely capped off and secured. The internal finishes and fittings would therefore also be nonstandard in this area. So could this combination cause some kind of detrimental enviromental change in the area where the ELT is located?
Given the number of ELT's in use its either the ulimate s*ds law that this has happened on a 787, or is there something specific about this ET version?
Is it known if there are any other operators using this configuration?