AF 447 Search to resume (part2)

[FlightPathOBN]

First off, I am not aware of any information in regards to the location of the impact...

Surface finds are not indicative of the impact site, but narrow down the 'ground zero' factor.

In my opinion, as i have located many underwater wrecks, is that the aircraft impacted the surface at near zero velocity, ie a flat spin.

One can note that the current debris field, has few artefacts with the potential for aerodynamic drift...

Opinion: This aircraft impacted the surface at a near flat spin. Due to the prevailing factors, it is likely that the hull was breached prior to impact. Even at terminal velocity, the surface area likely caused extensive breakup of the remaining structure, but allowed for structurally dynamic assemblies to remain intact. Given that aircraft assemblies are not designed for forces in this direction, it is difficult to predict the load diagram, and hence failure mechanism, and relative points, cannot be determined without extensive case studies....

[FlightPathOBN]

but to say she hit with zero velocity is simply remarkable.

flat spin...near zero forward velocity is relative...

the impact of the vessel had little forward momentum

the wreckage speaks for itself....remember the Titanic? the debris field was spread over 5 kilometers...

As I see you are from the dairyland,
when you go out tipping cows on Friday night, if you stand in front, will you be okay? exactly!

[mm43]

As lomapaseo has already pointed out, the concertina absorption of the initial 'g' forces through the collapsing of the belly section of the aircraft, resulted in only partial damage to the bottom of some items on the main deck. The galley is an example, along with a toilet/lav door which showed compression of composites over only a few centimeters along its bottom edge. Time v distance can turn an initially high 'g' force into nothing.

Also, one of the reasons the vertical stabilizer came away relatively unscathed.

[FlightPathOBN]

concur...the galley section is an example of where the structural assemblies after the cargo and fuel voids coincide..

ie...a belly flop.

[Bizman]

Machaca

Re Premier Plongee
http://www.bea.aero/fr/enquetes/vol....re.plongee.mp4

Did anyone else notice at time mark 3:14 to 3:17 there is a round canister shape at mid-left of frame exiting to bottom left.

Can anyone with better computer graphic capability than I examine those few frames, particularly at 3:17 to see whether this is the FDR Memory Unit that was found on Sunday 1st May?

Maybe I am reading too much into this, but if so, it is located very close to the FDR chassis, as shown by the large tube assembly at mid-right of frame that was also shown in the photos published by BEA on 27th April. In fact, that object appears in the still photo of 27 April. Unlikely, but makes me wonder if it was missed on the first path. To be so close to the FDR chassis would suggest separation within the aircraft on impact, but both chassis and memory unit were contained within the structure long enough to effectively descent together. Far fetched..... I suspect so, but a close look by a graphics expert would quickly eliminate this conjecture.

[Dehaene]

2nd box found

I just Heard on french news TV they found the 2nd box in a good state.

[Rangoon]

CVR found and recovered

Bea has post on its web site that they have found and recovered the CVR
Very good news !

From Bea web site :

The investigation team localized and identified the Cockpit Voice Recorder (CVR) at 21h50 UTC on Monday 2 May, 2011. It was raised and lifted on board the ship Ile de Sein by the Remora 6000 ROV at 02 h 40 UTC this morning, on Tuesday 3rd May, 2011

[wozzo]

BEA 3rd May 2011 briefing

The investigation team localized and identified the Cockpit Voice Recorder (CVR) at 21h50 UTC on Monday 2 May, 2011. It was raised and lifted on board the ship Ile de Sein by the Remora 6000 ROV at 02 h 40 UTC this morning, on Tuesday 3rd May, 2011.

3rd May 2011 briefing

[Bizman]

CVR located

Grat news!!!

Pinger still attached. That raises questions now about effectiveness of phase 1 & 2 search.

CVR itself seems badly distoted by movement in a forwards and UPWARDS direction by impact forces.

Interestingly the CVR is still mounted in the ARINC tray mount which appears to have cleanly survived impact forces. The tray mount itself separated from the supporting structure probably due to manner in which the tray is attached to the airframe.

[llagonne66]

Sorry for our dear conspiracy theorists !

Thanks to BEA that did not give up, thanks to AF and Airbus that footed the bills and against tremendous odds (A/C lost at night, in the middle of the Atlantic Ocean, in radio silence and resting 4000m under sea surface),
the two "black" boxes have been found.
Of course, all the people involved in this tremendous feat have done all that just to tinker with the data contained in the boxes.
Let's now wait for the data that we all hope is legible in the chips in order to understand what went horribly wrong that night.

[mm43]

Pinger still attached. That raises questions now about effectiveness of phase 1 & 2 search.

Judging by the photograph, the location of the ULB (half buried vertically) didn't enhance its acoustic radiation capability.

Locating the missing ULB from the SSFDR is probably on the list of things to do, mainly to assess why it was not detected either. Then try finding the QAR for good measure, you never know what it may provide.

[AlphaZuluRomeo]

Great news

Originally Posted by mm43

the location of the ULB (half buried vertically) didn't enhance its acoustic radiation capability.

Why is that? Because it's half buried? Because it lies vertically?
(not an acoustic specialist at all, here, just wondering : one can't really asks an ULB to "kindly lie horizontally above the seabed in case of crash", can we?)

[Bizman]

BEA is listening?

Did anyone take note that the BEA, on their briefing page:

Sea Search Operations, phase 5

... since 29th April, has been listing the English link ahead of the French link?
This is prominent in that the first two posts of 26th & 27th both listed the French link first.

It cant be geographical, a Brazil precedes all.
It can't be language, even those English precedes French, German and Portugese, as this would represent further deference to English, as French for "German" is "Allemand".

Maybe Bearfoil is finally getting to them!

Personally, I am very appreciative of the BEA's posts and photos. It strikes me as openness, certainly not gushing, but measured and respectful, and reassures me that finally, this sad and tragic accident will yield a factual description of the event. Hopefully not too long, as I hope they may release another Interim Report based on initial FDR/CVR data.

I can't help but feel profoundly saddened when reading an annotated passenger list ...
Unofficial Air France 447 Passenger List

Hopefully, their involuntary sacrifice can now be more certain of yielding data to lead to many more lives saved. Theirs, and their loved ones, has been a huge price. Their loss is respected if all who are now serving through these two finds, to unscramble this omelette, do so in a careful, factual, neutral, open manner. I look forward to this result.

[skadi]

Bizman

Did anyone else notice at time mark 3:14 to 3:17 there is a round canister shape at mid-left of frame exiting to bottom left.

Can anyone with better computer graphic capability than I examine those few frames, particularly at 3:17 to see whether this is the FDR Memory Unit that was found on Sunday 1st May?

For me it looks like an Oxygene bottle....

[Squawk_ident]

JP Troadec interview

At 10h41 LT 08H41z on French Radio "France Info"

quick transcript

The outside of the CVR is good
At the end of next week BEA will proceed to the opening of the "boxes". It should be quick except if corrosion is present. Reading may take some days or some weeks accordingly. CVR records the last two hours of flight. We now think that we will be able to understand reasons of the crash according of the precedent elements of the inquiry and the present recoveries.
We will try to recover some pieces but not the entire aircraft because it would be useless for the inquiry and it is very long, about 6 hours to go up and down again.
Parts that we will try to recover are on board calculators because of their own internal memory, engines and the cockpit. It will be difficult for the cockpit because there are a lot of debris around.
I won't speak about bodies recovery. It is not the BEA mision but the one of the French Navy.

[chrisN]

I got the 100-200g figure from an earlier posting that mentioned those figures in relation to injuries seen on recovered bodies, which in turn I thought must have come from BEA or authorities close to them. I can’t quickly find the quote.

The people were in the same fuselage areas as the galley, both remote from the immediate impact with the sea; and the lower parts of the fuselage would act as energy absorbers, but also with the whip crack possibility mentioned above enhancing velocity, and ultimately g as movement ceased; but it still seems remarkable to me that such a disparity can have occurred. I do know that queer things can happen in accidents. I have seen a very small number of aircraft and car accident details, but none of those led me to conceive of an anomaly such as posed here, if the g reports are anything like correct. One or two passengers may have experienced a particularly high and thus atypical g, but I am surprised that it seemed to be the norm, when the galley was so little damaged.

Anyway, thanks to those who responded.

[BJ-ENG]

@lomapaseo

How does 100-200gs on a persons body equate to G loadings on a CVR/FDR? innards
How does 200 atmos pressure at the bottom of the sea cause damage to a memory chip in a module if it is exposed to water intrusion?

If I deal with your question on pressure first; at 4000m, the pressure at that depth is 398atm, or 403 bar, or 411 kgf/cm2, or 5846psi, or 2.9tons/sqin. Starting from the point that a hollow object if present in a fluid at high pressure, is filled with air at normal atmosphere, and has a small hole, lets say a microfracture, water will enter, albeit veryslowly, but enter it will, eventually compressing the air to 1/400 it's volume and replacing the balance with water. Integrated circuits of the old plastic dual-in-line through hole type are formed by a solid layer of resin plastic which covers the entire microcircuit die. Ceramic devices (wide temp spec types -40 to +125C for the military) have a cavity above the microcircuit which if subject to high pressure is prone to fracture. Similarly, the small Surface mount devices (like we see in mobile phones), have an enclosed void under the die inside the resin, which again is subject to failure under pressure. Now, if the FDR/CVR armoured case leaks, water will inexorably progress into all parts of the interior, around the electronics, and cover The memory devices until, when the flow has stopped and there is no differential to the outside, they too are subject to the same pressure that exists outside of the cylinder. If the memory device uses a package which has a void, then it too may suffer a stress fracture, and again, water will find it's way in until the pressure differential goes to zero. Plastic IC's are now much more prevalent in aerospace than I at first thought. That being so, if plastic parts are used, then the porosity of the plastic will allow ingress of water without the need for any fracture event. The links below show how fractures may occur when IC's are stored in a damp environment and then suffer damage during the heat treatment process required to mount them on PCBs. In this case at far lower pressures since the material is in tension due to expansion, whereas, in compression they are much stronger.

http://nepp.nasa.gov/docuploads/A178...ems_final2.pdf

Moisture absorption

Regarding the question of equating acceleration on a person's body and that experienced by the FDR, and by implication, the CVR. The summarised findings of BEA's pathology report suggests a more or less horizontal impact. White's study (1993 The effects of structural failure on injuries sustained in the M1 Boeing 737/400 disaster) used injury analyses to allow direct comparisons with other linear measurements of a similar scale to show that severity of the injuries mirrored the damage to the aircraft. Similar suggestions were made by Cullen (NATO - Injury Mechanisms in Aircraft Accidents ) who concluded that the method be considered in the analysis of accidents where it is not possible to examine the crashed aircraft, such as accidents over ocean. The manual for civil aviation medicine quotes: Examination of the bodies of passengers can establish a pattern of injuries. Such a pattern may be uniform or discordant. A uniform pattern suggests that all the passengers were subjected to much the same type and degree of force.

For an accident over terrain, the forces acting upon the occupants are frequently less than those applied to the aircraft ie; the structures may show more damage than the injuries to the occupants suggest since the aircraft structures absorb energy as the collapse progresses. A water impact is different, and passengers are likely to be subjected to higher forces for the reasons explained before, namely; failure of the buckling absorption process in the structural members, and hydraulic shock to the floor structure. Once the skin fails, the drag profile changes as does the loading on the structural members. The floor then takes the brunt, and when that fails, the upper outer skin panels.

Passengers and FDR/CVR are, if I recall the details of a photo in an earlier post correctly, located at similar heights above the aircraft datum lower fuselage - maybe the FDR/CVR are a bit higher, though with a slight pitch up as mentioned in the report, this might have put the FDR/CVR to the same level or lower. So, as a first approximation, if we take horizontal impact on terrain as an exemplar, the stopping distance is similar, with the frames further forward of the empennage taking the energy until either the empennage contacts the ground or breaks away at a frame section. Hence my comment; the FDR and CVR may have experience something similar or less.

It can be argued that a small equipment object like the FDR could experience any number of pathways to final stop (air/water boundary), and that trying to predict how energy is absorbed and max G is fatuous. However, in this instance we are dealing with fluid dynamics where for a small object (low cross sectional area), the effects of drag, and by implication, retardation force is likely to be lower than that experienced by passengers subject to a hydraulic surge which pushes up against the large surface area of the floor. Examining the FDR photo I note that there is some damage at two points to the end of the casing consistent with contacting a hard edge, probably when the pinger departed. What is more interesting is the way the support fixings for the memory cylinder have failed. On the top two lugs where the earth strap is located, it looks like both bolt heads have popped off, while for the lower two, they look as if they are distorted - slightly bent. This suggests to me that the cylinder received a force low from one side which was sufficient to lift the unit, causing the bolt heads to fail, and bending away from the chassis (possibly explaining the chassis distortion) until the lower bolts failed, but not before bending sufficiently to remain trapped in the cylinder supports. Yet, if this was the case, then where is the associated impact mark on the cylinder paintwork? One hypothesis is that the cylinder was detached from the chassis as a result of fluid forces, and since the rising edge (dp/dt) of a fluid pressure pulse is less severe than a hard object impact, and the deceleration on a small object correspondingly less.

Could the cylinder have hit something else, the chassis for instance, and experienced a high G from that source - the answer is yes, of course. However, unlike the passenger G event, which might occur over a longer period, anything from say 100 to 300 ms, with a vertical vector, a detached memory cylinder is likely to experience only brief interactions, and varying vectors mitigated by fluid drag. So it's quite possible that the FDR experienced less G than the passengers.

Note: for ChrisN - Guidline from manual:

Injury sustained Deceleration
Nose - fracture 30G
Vertebral body - compression 20-30G
Fracture dislocation of C1 on C2 20-40G
Mandible - fracture 40G
Maxilla - fracture 50G
Aorta - intimal tear 50G
Aorta – transection 80-100G
Pelvis – fracture 100-200G
Vertebral body – transection 200-300G
Total body fragmentation >350G

Apologies for the length...

[grity]

@ chrisN
if you take a currugated paperbord chair, his own wight is less than 1 kg, you can sit with a whight of more than 100 kg on him without problem or deformation


if the the same empty chair chrash with 100g, the deformation will not be bigger.....

the gally is a very light and very stable construktion

[dufc]

Does anyone know if the discovered debris field contains ALL parts of the aircraft (except for those recovered earlier from the surface) or if some sections are still missing?

If some sections are still missing this might indicate a break-up prior to impact with the ocean.

The converse however would suggest the aircraft was indeed intact upon impact.

[grity]

@BJ-ENG one chrash-load to the CVR will be the falling FDR in vertical chrash....