AF 447 Search to resume (part2)

[JD-EE]

Centosphere

JD-EE,

"Centrosphere, what you are seeing is compression artifacts."

Good take, but what kind of compression technique these cameras utilize? I really doubt it will be something different from the standard JPEG 4, what is a quite developed standard and delivers high picture quality. Alas, the ROV is tethered, they probably donīt have a problem with bandwidth.

Um, where did you find the raw uncompressed images to look at? All I saw were pictures taken of a video screen at a slightly oblique angle. The smooth looking area was dark. The image was jpeg. The jpeg probably smoothed the image a little. And it could also be smoothed by other effects mentioned since my comment. It's WAY premature to make anything big our of it.

[JD-EE]

deSitter....
(me mumbling) Video == vidicons. Stills == film. The blooming looked so "vidicon" that my mind fastened on that forgetting vidicons are hardly high definition toys. My bad.

[Chris Scott]

Quote from Machinbird:
On a local level within the aircraft, Whatever was below greatly influenced the damage pattern above.
The FDR may well have been thrown up into THS structure with the initial hydraulic induced debris flow.
I really suspect that the THS structure was then pushed up and aft out of the aircraft, throwing the aft part of the VS upward and forward and taking a bite out of the rudder bottom as it passed by.

As a non-structures man, am reluctant to try and add to his compelling description, but it might be worth developing a point I made last night. I was speculating that the large surface area of the tailplane (OK, I'll call it the THS) would cause it to decelerate faster than the fuselage forward and aft, just as Machinbird implies. I wondered if this might cause the fuselage to fail forward as well as aft of the THS.

It seems very likely that the APU tailcone would break off. But I notice that some posters seem to be referring to the whole of the rear fuselage, aft of the pressure bulkhead, as the tailcone. Looking at the cutaway sketch posted by PJ2, and Machacha's picture (re-posted by susu42), it seems clear that the aft pressure bulkhead is forward of the front of the THS. If I understand correctly, the THS screw-jack acts on the front spar of the THS, and the photo shows it something of the order of 2 metres aft of the pressure bulkhead and DFDR/SSFDR chassis.

So, as I speculated earlier, how about the fuselage failing also between the pressure bulkhead and the screw-jack? In that case, the SSFDR chassis and/or memory module might not be "thrown up" into, and then with, the THS.


PS
Can anyone tell me what the large bare-metal strut in the middle of the photo is for?

[Green-dot]

Quoting the BEA:

The forward and aft parts of the airplane are broken apart and mixed up, which means that a time-consuming systematic search is required.

The wreckage was found to be mixed up. I wonder, could the aircraft after its initial relatively flat impact have bounced and cart wheeled on the ocean surface, mixing the wreckage at that time, or did the mixup occur during its 3,900 meter descent to the ocean floor? If it cart wheeled, the CSMU's trajectory after it broke loose may have been such that it was thrown some distance from the rest of the tail section before starting its descent (and the same goes for the APU). It may also explain why the engine found was detached from its pylon.

[Centrosphere]

JD-EE,

Yes I know I promised to keep quiet, but I feel an obligation to answer this...

"Um, where did you find the raw uncompressed images to look at? All I saw were pictures taken of a video screen at a slightly oblique angle."

This seems to be an application of Occamīs Razor, but letīs confront the full consequences of this approach:

a) if youīre BEA or someone hired by them, you would need the raw images, and probably you would even use software to enhance the images _ you would never use compression algorithms that delivers loss of information. Thatīs my problem with the "compression artifact" thesys. Alas, the rest of the image is very crisp and detailed.

b) if you have the files of all raw images you dream of, why the hell you would use a picture from a monitor in the much awaited press release? Have you seen at least one other picture like that yet?

Again: maybe there is nothing in this issue after all, but some things seems illogical.

Now, back to the low profile...thank you for your attention.

PS: someone back the thread came with one good explanation: maybe the ROV took the picture after being closer to the chassis, probably looking for the CSMU. This seems to be a sensible explanation, better still that the "human remains" hipothesys, imho. I donīt know the amount of dislocation the ROV creates, but depending on the distance of the soil to the hovering ROV, this could indicate the nature of the soil below, that I believe is not very thick in mud.

[Zeroninesevenone]

Photo

Looking the edge traced version of the now famous photo, I cannot see any alteration, nor compression artifacts.

All the contour lines in the blurred area are in line and linear with the rest of the contour. It is just darker, so I'd say that the blurring is because there is sand/mud flying over the central area, perhaps because the ROV has moved the box a bit to see if the CSMU is there or not. Definitely not because of any alteration.

[infrequentflyer789]

Originally Posted by Centrosphere

a) if youīre BEA or someone hired by them, you would need the raw images, and probably you would even use software to enhance the images

Yep, but we are not they. We are looking at press release images intended to show the unwashed masses what has been found, not images for detailed anaiysis.

Remember, this is a photo of another photo (or maybe even just a screencap from video stream) on a monitor, with all the losses that entails, before we even get to compression

_ you would never use compression algorithms that delivers loss of information. Thatīs my problem with the "compression artifact" thesys. Alas, the rest of the image is very crisp and detailed.

If bandwidth and storage are infinite, then you'd never use lossy compression They aren't, and trade-offs are made.

b) if you have the files of all raw images you dream of, why the hell you would use a picture from a monitor in the much awaited press release?

Because you want (commendably) to show the world what you've found in a timely manner, not provide the world with the highest resolution for analysis.

The high-res images are probably still on the boat (why waste sat bandwidth sending hi-res back to land - the search professionals are on the boat)

The hi-res image may still have been only on the ROV when the photo was taken and sent back for PR (it might even be screen cap from a video stream - not sure how we'd know from a photo of a screen)

[bearfoil]

Chris Scott

PS
Can anyone tell me what the large bare-metal strut in the middle of the photo is for?

There are two penetrations in the footprint of the VS atop the Hull. Given the stout appearance of your strut, and its angle, my guess is it is an extension of the VS Spar into the Hull, for strength's sake. This is a mere guess, so be gentle.

[Centrosphere]

infrequentflyer789,

Good takes. Letīs see:

Remember, this is a photo of another photo (or maybe even just a screencap from video stream) on a monitor, with all the losses that entails, before we even get to compression

I do agree. Nevertheless, I never saw a "loss mode" like that. Degradation from copy should be evenly displayed all around the photo, not localized in a spot.

If bandwidth and storage are infinite, then you'd never use lossy compression They aren't, and trade-offs are made.

The same objection holds. Besides, you donīt need "infinite" storage, only the storage needed to store the output of the sub cameras. And since the data can be transmited (after all, we are seeing the images), the storage on board is practically infinite.

The high-res images are probably still on the boat (why waste sat bandwidth sending hi-res back to land - the search professionals are on the boat)

Not a reasonable assumption because: a) I canīt believe bandwith is a problem to an Alcatel owned ship; b) sat bandwith is not that expensive comparing with all the past, present and future costs of this operation; c) top level brass at BEA probably wants all the information management right under their wings.

[Centrosphere]

Zeroninesevenone,

All the contour lines in the blurred area are in line and linear with the rest of the contour. It is just darker, so I'd say that the blurring is because there is sand/mud flying over the central area, perhaps because the ROV has moved the box a bit to see if the CSMU is there or not. Definitely not because of any alteration.

Maybe youīre right. Anyway, thank you for demonstrating to some uneducated fellas here that THERE IS a blurr after all, and it is not a figment of my imagination!

[HazelNuts39]

Originally Posted by Chris Scott

Can anyone tell me what the large bare-metal strut in the middle of the photo is for?

Seems to me to be a duct, wrapped in an insulating blanket. Look at the 'knee' at the top.

Originally Posted by zeroninesevenone

the blurring is because there is sand/mud flying over the central area

I repeat my belief that the darker area contains finer sediments because it was sheltered from currents by the box. The deposits on top of the inverted chassis show that sediments have been moving.

[Chris Scott]

bearfoil,

That's what I thought it might be, but it seems off to the port side of centre, so I think HN39 is right: it's trunking, not a strut!

Which brings me to my next two questions.
(1) What is the grey-painted member like an inverted "Y" – is it THS-related or fin-related?
(2) What is the complex apparatus that the operative is fiddling with?

[bearfoil]

Chris Scott

I'll plod ahead, since I have no shame. The engineer appears to be working on an assembly that has bellcranks, pushrods, Hydraulic pumps, plumbing and some intricate looking mechanical architecture. Ignoring Hazelnuts at my risk as ever, if the "Strut" is the Rudder post, the assembly may be RTL. I see Hazelnuts "knee" and he could well be right, especially since I thought RTLU was in the VS. I'm better at diagrams. Then again, it could be a conduit for the Rudder hydraulics, along with the RTLU hydraulic power. Cheers.

[Chu Chu]

My mind keeps connecting the orangish cast in front of the chassis with the darker area behind it. Can't come up with a theory on what that connection might be, though.

On the other hand, maybe they felt this overwhelming urge to voluntarily release a photo with something they wanted to hide in the frame. Cropping the photo or taking one from another angle might arouse suspicion, so they altered it. Craftily, they did this in a way that's immediately obvious from a glance at a low-res copy. After all, no one would believe that an organization capable of locating and exploring a wreck on the ocean floor while engaging in a sophisticated deception scheme would be so clumsy about altering a photo.

[PJ2]

Chris;

The operator is working on what I believe to be the Rudder Control Unit. The control rod that the BEA notes is bent rearwards, would be located at the top of the unit, not visible in the photo. I'm not sure what the round structure is - could be channeling or it could be structural - it's difficult to say where it is - underneath the RCU, or behind it nearer the airframe structure. There seems to be some robustness about it, especially on the bottom attachment - what we can see of it, anyway. I thought it may be APU pneumatic supply because of the shrouding but the source I have shows that plumbing to be on the starboard side. Still, manufacturing changes could involve routing changes, etc. The upside-down "Y" structure I believe is part of the rudder control cabling channeling, to do with the rudder mechanical control which is aft of the RCU. The sources I have aren't that definitive at times.

[HazelNuts39]

Originally Posted by bearfoil

it could be a conduit for the Rudder hydraulics

Considering how the pipe is plugged in the upper right corner of the 'rear part' in the photo posted by NeoFit #222 on page 12, must be very, very low-pressure hydraulics.

[henra]

Originally Posted by deSitter

No question it's the APU, obvious really. The airplane is torn all to hell. I don't see how this is possible without a high speed impact.

Hmmm, looking at the damage pattern I do see heavy compression damage but almost no longitudinal damage at all.
In a high- speed forward impact you would however expect the latter.
So for me this image is a strong indication of a 'pancake' arrival attitude.

Also it is good to see that it has not sunk much into the silk so the bottom fortunately appears to be rather firm. Which is good news regarding chances to find the CSMU.
Looking into the very open structure in the back I'm also confident the CSMU is not resting cramped in another structure, especially since it has a rather streamlined shape which makes it hard to get entangled somewhere. Try to fix a cylinder somewhere without bolting it to a support...

[PJ2]

HN39;

Thanks for the reminder about Neofit's post, (#222) - I hadn't seen the photos.

I believe that the large dark pipe is pneumatic supply from the APU. The APU pneumatic bleed plumbing runs along the top port side of the APU and through the APU firewall (in the tailcone structure) and joins the top right-hand side fitting where we can see the APU pneumatic pipe (yellow capped), about ten inches in diameter. It is of the same "insulating" material as the dark pipe standing almost vertically on the starboard side, which we see in Machaca's linked photograph of the operator in the tail section. I think the small attached wire (left side of the vertical pipe in Neofit's image), to the larger pipe, carry the APU Bleed-air Duct Sensing Elements.

In Neofit's linked image of the aft fuselage, the fixtures at the mid-point of the two cross-frames are the forward fastening mounts/pivot points for the THS.

[HazelNuts39]

Originally Posted by PJ2

In Neofit's linked image of the aft fuselage, the fixtures at the mid-point of the two cross-frames are the forward fastening mounts/pivot points for the THS.

That rear frame is an interesting structure. Trying to understand the thinking behind it, I guess the need to 'mount' the THS within the fuselage structure dictates it, i.e. the need to disassemble the double links at both sides when 'inserting' or removing the THS. Just curious how these links look like after the event.

[PJ2]

HN39, I'm not an engineer and know nothing formal about structural work. That made clear, my sense of the triangles thus formed is that they receive, then transfer and distribute mostly-vertical loads of the horizontal stabilizer to the larger aft-fuselage structure. The very beefy forged/milled joins between the top and bottom of the aft section where the THS is mounted appear to mean business in load-bearing. The aft frame (APU tailcone structure) is, IIRC, similar in the bracing seen here but of course, smaller. Perhaps too, these twin-braced major frames counter "twist" (as viewed from the rear), which would come from loads borne by the vertical stabilizer hoops shown earlier, which would be transferred to the lower structures through the hoops.

All this of course a complete guess and could be wrong, but it "feels right"...I would welcome corrections.