Power-wise, this unit is completely self-contained, self-testing and with a ten year battery life.
The only electrical integration with the aircraft's systems would seem to be this connection to a flight deck 'test switch'. Are all Honeywell ELTs connected to the flight deck or just those fitted to the 787? I am struggling to see how a low voltage/data connection can cause a fire, even when incorrectly connected. And the unit itself in a quiescent state is unlikely to draw more than a few milliamps from the onboard battery, not unlike an electric clock battery which can tick for several years on a single AA 1.5 volt cell. I can only imagine that if the beacon is the cause of the fire, it somehow suffered some mechanical damage either inflight or during manufacture and installation. |
The requirement for a remote switch in the cockpit on all new installations has been around in the US for 10+ years. All aircraft all installations.
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ELT - a good idea in any and all aircraft
It is self contained and there to help SAR teams get to you in the event of a crash. Of course you are right in that most all commercial operators have satellite tracking regardless of control zone type. What if aircraft power is lost suddenly or standard communication equipment fails? Or what about a sudden event where the crew could not get out a distress call?
Modern 406 ELTs transmit exact position for an extended period of time. Very useful if one ever had to ditch and was floating around in the sea. Also useful regardless because the ELT will outlast any other electrical communications after an event. Bottom line: one faulty ELT is hardly cause to discuss getting rid of them all together on scheduled airliners. |
I wonder if Boeing EE's are tracing the route of electrons from the ground power receptacle throughout the aircraft to see how current could leak into the ELT circuit. Let us suppose that they find something that allows a stray voltage to wander here or there. Hmmm.
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 would lead to a pre flight test where a CC or maintenance crew accesses the ELT test switch, and either confirms the light or the flight deck crew are listening up on the ELT's freq and confirm via intercom good test or bad. Yes, it's a crew coordination drill, but you don't need an ELT unless you are intending to fly in the first place. You always fly as a crew. It may also be in the too hard category, in terms of getting access to a test switch from inside the cabin. Just thinking aloud here ... |
Suggesting that these things are switched off rather than removed, suggests that there may be a problem with their operation rather than their manufacture or installation.
Can they know that by now? :confused: |
SOS:
I can only imagine that if the beacon is the cause of the fire, it somehow suffered some mechanical damage either inflight or during manufacture and installation. The larger the temperature swing the more mechanical stress there is. Wonder how hot the unit gets when parked in the sun in Africa? |
Suggesting that these things are switched off rather than removed, suggests that there may be a problem with their operation rather than their manufacture or installation. |
here is a report
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My reading of the AAIB safety recommendations is that it is only the fixed ELT that is required to be switched off and NOT the portable devices or those attached to life rafts.
Could that be because they are different units or because they are not located in close proximity to a composite structure and are difficult to access in flight? I take some poster's points about a crew in flight having a time advantage over the ground firefighting crews when tackling the fire. But reading about the firefighting efforts in the report, I doubt it would be easy for crew members to do this in flight given that the firefighters had to hack away at ceiling panels to tackle the fire with water after failing to control it with halon extinguishers. This could have been extremely nasty! :( |
I wonder if Boeing EE's are tracing the route of electrons from the ground power receptacle throughout the aircraft to see how current could leak into the ELT circuit. Let us suppose that they find something that allows a stray voltage to wander here or there. Hmmm. I presume it has an external antenna? I hope nobody did a bad thing with antenna grounding. |
Don't forget in all this that 'in flight' would probably result in depressurisation of the aircraft making life a lot harder!
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The Bulletin doesn't recommend just turning the unit off, it recommends making it inert. Big difference. |
Pitts #452, the version of the report I have downloaded interestingly states "the only _significant_ thermal event".
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Murphy, on smaller aircraft (think King Air, small jet) they are usually aft of the pressure bulkhead in the tail. On larger aircraft (think G-IV and up) they are usually inside the pressure vessel, to prevent cold soak problems on long flights.
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Having just experienced the Dream Maker and the Thomson Premier Club product to Orlando, all I can say as a passenger is WOW! My vacuum is noisier than a full load departure compared from the forward cabin and the pressurisation meant that after a nine hour flight we arrived amazingly refreshed! For me, this aeroplane is frankly brilliant. No smoke, no fires and no drama! Loved the HUD for the crew! Thomson have it 100% commercially aligned with the market. Premium it certainly is! The 787 and the A380 are remarkably quieter than the aircraft they are replacing. |
Ban Lithium-anything batteries from ANY airborne system!!!!
AAIB recommends review of all lithium-powered ELTs after 787 fire | Reuters |
Ban Lithium-anything batteries from ANY airborne system!!!! |
The guilt or innocence of the ELT will become clear in due course.
Of more concern are the problems that the firefighter(s) had in getting to the fire and extinguishing it. Also, the lack of detail of the damage is interesting (I still await the videos of the fire and the close-up photos). |
When we installed the ELT on the '380 the most "difficult" part was wrapping the antenna feeds with fireproof material to ensure that the installation as a "whole " met regulation re-fire/heat resistance.
It seems a somewhat moot point that there is no airframe insulation in that self same area of the 787 by design....:\ |
If these are now catching fire without an external ignition source, it's not good Edit to add link: http://www51.honeywell.com/aero/comm...06_AFN_ELT.pdf |
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