hurricanemk1c 195 Posted April 4, 2011 Report Share Posted April 4, 2011 Yep, it's been found - http://www.bbc.co.uk/news/world-europe-12953432 Just wondering how the black boxes are standing up/stood up. Salt-water isn't the best for any metals Link to post Share on other sites
allardjd 1,853 Posted April 4, 2011 Report Share Posted April 4, 2011 That's one of three challenges. The first two are actually locating the boxes (as opposed to a general area of wreckage) and the second will be recovering them. Neither of those will be easy even if the general location of the wreckage is known. I've read elsewhere that the sea bottom in that area is essentially a mountain range, which isn't going to make things any easier. We've all seen air crash photos where the tail section comes off more or less in one relatively intact piece. I know that one of the tail surfaces was recovered in the floating wreckage. It's possible that the tail section of 447 may have come off in the impact and floated off some distance from the rest before finally sinking, so finding wreckage from the AC doesn't guarantee that the tail with the recorders is there. As for recovering the data, that too is far from a sure thing. It won't be on tape - the AC was far too modern for that to be the case. It will be stored on some kind of digital media, either something like a hard disk or perhaps on flash memory chips as we're familiar with in USB thumb drives or SD cards. It's not reasonable to expect that seawater would not have entered the cases. Even if they were undamaged in the event, I doubt the boxes would maintain a seal over two years at those kinds of depths where the sea pressure is enormous. I think seawater intrusion is probably a near-given. That gives rise to concerns over corrosion, as you mention. Aluminum in particular is pretty reactive and is often the substrate for hard disk platters and sometimes for pins and contacts. Silicon, on the other head, is relatively immune to such things. On the positive side, cold temperatures make most chemical processes go slower, corrosion included, and the oxygen content of the water at extreme depths can sometimes be quite low too. Solid-state electronic circuitry is usually suprisingly good at withstanding immersion with one large IF - IF there is no voltage present. As long as the circuits are un-powered before the water is introduced, they often survive pretty well and may function just fine after being thoroughly cleaned and dried. If there is voltage present, the water causes shorts and current flows where it's not intended to. In a case like that, sudden immersion is probably better than slow leakage. In the case of the 447 recorders, it's hard to say. There were reports that the pingers were heard faintly by a French submarine that was participating in the early search effort, indicating that battery power was available. That may or may not bode well for the actual memory circuits, depending on whether the pingers are a separate module or not. I don't have a clue how these things are built. I'm sure they are designed with crash g-loading and fire and immersion in mind but not necessarily at those depths for that length of time. The bottom line is that there is plenty to still be concerned about and recovery of the data is far from a sure thing at this point. It is to be hoped that it is intact and can be had, but I sure wouldn't bet any money on it yet. One has to admire the tenacity of the French in this so far - they haven't given up easily. Link to post Share on other sites
hurricanemk1c 195 Posted April 4, 2011 Author Report Share Posted April 4, 2011 Good points John - the main wreckage site is (apparently) 600m x 200m including fuslarge, wings and engines. No mention of the tail. All this does indicate that the aircaft remained *relativly* intact - I say that as some things may have fallen off before hand and floated off EDIT - I found this on Wikipedia (maybenot the best, but gives us a general idea) - Currently, EUROCAE specifies that a recorder must be able to withstand an acceleration of 3400 g (33 km/s²) for 6.5 milliseconds. This is roughly equivalent to an impact velocity of 270 knots (310 mph) and a deceleration or crushing distance of 450 cm. Additionally, there are requirements for penetration resistance, static crush, high and low temperature fires, deep sea pressure, sea water immersion, and fluid immersion. Doesn't say how long it'll last, although it does say that modern FDR's have two layers - a strong corrosion-resistant stainless steel layer or titanium, with high-temperature insulation inside Link to post Share on other sites
allardjd 1,853 Posted April 4, 2011 Report Share Posted April 4, 2011 Airbus should know how it's built and logic would dictate that the money wouldn't be spent if there's not at least some reasonable chance that the data will be intact. On the other hand, decisions like this are often more political than practical so I don't know. The stainless/titanium can and the "deep sea immersion" factors are relevant and are positive inticators that there is at least a chance. John Link to post Share on other sites
Tim_A 997 Posted April 4, 2011 Report Share Posted April 4, 2011 No mention of the tail. I thought the tail-or at least, much of it-was recovered early on as floating wreckage. Link to post Share on other sites
allardjd 1,853 Posted April 4, 2011 Report Share Posted April 4, 2011 One surface only. John Link to post Share on other sites
Tim_A 997 Posted April 4, 2011 Report Share Posted April 4, 2011 Ah, okay. Link to post Share on other sites
allardjd 1,853 Posted April 5, 2011 Report Share Posted April 5, 2011 Some photos here... http://www.bea.aero/en/enquetes/flight.af.447/images.du.site.php Link to post Share on other sites
allardjd 1,853 Posted April 8, 2011 Report Share Posted April 8, 2011 Bodies from Air France Flight 447 are found http://www.airfrance447.com/04/04/bodies-from-air-france-flight-447-are-found/ Too good not to post... "Side-scan sonar detectors attached to an unmanned submarine discovered a field of debris across the ocean floor nearly 600 feet off the coast of Brazil." Link to post Share on other sites
stu7708 244 Posted April 8, 2011 Report Share Posted April 8, 2011 No wonder they havn't found it until now, they must have been searching in the wrong place way out in the Atlantic Link to post Share on other sites
allardjd 1,853 Posted April 29, 2011 Report Share Posted April 29, 2011 There is a photo this morning of the FDR chassis, all by itself, lying upside down on the sea floor. It's not tangled up in wreckage and appears that it will be very easy for an ROV to recover. On the bad news side, the cylindrical, external "Memory Module" is not attached. Obviously this is a huge and positive piece of news, though the missing memory module is worriesome. John http://blogs.crikey.com.au/planetalking/2011/04/28/outer-casing-of-af447-flight-data-recorder-found/#comments Link to post Share on other sites
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