s-mode data do not show zoom climb: vertical velocity is always negative after initial event

No trim tabs here. It's FBW.

Just big elevators controlled by the ELACs and SECs, two actuators per elevator, one each side is from blue hydraulics and the remaining two are from green and yellow respectively.
ELAC 2 is normally in control, if it fails then ELAC 1 takes over, if it fails then one of the SECs does.

Any GPS readings after the initial event are likely to be unreliable, as I explained in an earlier post http://www.pprune.org/rumours-news/5...ml#post9168602
Both GPS antennae are normally on the top of the fuselage, one over the cockpit and the other a little further back and most usable satellites are above the height of the aircraft. The antenae require direct line-of-sight with no obstruction. With the aircraft tumbling its very likely that that will not be the case for much of the time. This will cause a lot of random spikes as my earlier post explained.

100% "Intriguing. I have put the broken part back in position, but they still make little sense."

Could they be scrape marks from sections of the HS flailing around as the whole assembly tumbles, prior to departure of the two main HS components ?

In previous pics of the HS on the ground, there are numerous strips of composite about the width of the scrapes.

andrasz It was one guy from Smolensk, not me.

@Filler Dent

"No trim tabs here. It's FBW."

The jackscrew is the trim mechanism.

On the idea of the huge variations in vertical speed without corresponding altitude changes: This is fairly easy to explain. (At least possibly)

After the tail separated the plane almost certainly tumbled numerous times. (This also explains the disintegration of the weakened rear fuselage up to the wing box- where it was strong enough to resist the continued failure of the fuselage skin...) As it tumbled roughly around the middle of the now altered CG the nose would have gone through a series of oscillations in quick form. Down at an extreme rate until the nose passed through the vertical facing downward, then up at a fantastic rate while the nose rotated up to the vertical again, before once again beginning the down cycle as it passed through the vertical.

Because the pitot static system is located in the front of the airplane (almost as far forward as it can) the readings would have been way out of whack, and would correspond at least generally to what was seen on the traces.

Finally: A flat spin: This almost certainly did not happen as there was nothing left to induce the adverse yaw necessary to initiate the autorotation required for such a spin. Further the impact shows pretty clearly that the wings were not rotating about the yaw axis in any meaningful way. If one engine failed and the other continued generating thrust it is at least theoretically possible that the airplane could have been forced into a spin, but given the weight and balance of the failed fuselage to that point it is incredibly unlikely that this happened.

Just my .02 as always,
dce

While this would be true in general but the gps data in s-mode also include gps accuracy and the first high g spike (~50g) is recorded while accuracy is still high, the issue here is that we do not have a timestamp at the transmitter but only at the receiver so it is hard to claim accuracy when computing accelerations

Are you sure? A large part of the leading edge of this one appears to missing entirely.

http://www.pprune.org/rumours-news/5...ml#post9174846
(trying to link to picture of the broken HS in FDMII's post #1862)

The VS isn't exactly in good condition either... ?

While the last reported instrumentation readings may not be reliable for directly showing the flight path of the plane, they may still be indirect evidence of it. Assuming (yes, big 'if') that the sensors were still functioning properly, can anyone with knowledge of the plane's systems suggest what gyrations could produce those readings?

Juggling the dimensions, I hope I got it right when I estimate the red arrow to be 94 cms long.

Pasteboard ? Uploaded Image

Hope you can see the picture. It is from the tail fin.

in answer to the questions about the engines.
the damage on the fan blades is not consistant with a blade failure. i have lots of pics to compare against, unfortunately cannot share. IP reasons
if you watch the A380 blade off test on utube around 4:50 you will see the damage being done to the tips of the blades, not very detailed but best there is out there. i was hiding when they filmed that.
damage is ground impact damage.

To whom it's fancy to read a lot of Russian letters - another explanation of cause of tail separation, based on forums investigation.

TLDR: fatigue failure of upper APU section mounts

For me it seems unreasonable that gap in the tail part can be unnoticed for a long time.

Oh nice work boys re the VS and putting it the right way up :ok:


RYFQB I think you were right that there is one further line, partly visible on the original image at least. It appears to be the same distance apart again as the other two are from each other.


I cannot find an image of the internal structure of the VS that shows anything at this particular angle though.


If it was an external object which caused what appears to be paint loss along these lines, I can't for the life of me think what it can have been.

scratches on fin
 

Thanks for doing reconstruction image of tail fin. I had something like that in my mind.
these vertical scratches were not present before crash. And they must have happened in flight.
They are located right over HS trailing edge. Could be marks from departing HS. Note how parallel these scratches look! Same event?
It could mean that forces that made HS to fail were from below, relative to fuselage of course.

@triumph61
 

When you try to make sense of these pictures, the questions with these components are:

a. are they in the place they landed on impact ?

b. or were they lifted or dragged to the side after impact to either get them out of the fire, or get better access to put out the fire, or lifted to search for and recover the victims ?

when a., this could suggest an inflight fire,

when b., this would require checking for dragging marks on the ground, and if not, for a vehicle with a crane with sufficient capacity,

I have not checked the ground or debris for dragging marks (again a better top down view picture would help). But have seen the white vehicle/truck with the 0.5-2.0 ton crane at the back. So lifting and being laid to the side is a clear option.

My impression is - low probability that both the L2 and R2 panels broke away from the fuselage at almost exactly the same time and altitude, and at low altitude (because they are so close together) ... So the burn marks could well have come from being exposed to the fire that destroyed the forward fuselage. And the panels then moved to the side, away from the center of the fuselage.

By the way, this is an example of the fact that investigators have better access to this class of input information.

What you really need to examine are all the fractures. Which is precisely what the investigators will do. Those fractures will tell you the direction of the forces that caused the fracture, and from those you can start to build a picture of which bit broke what.

None of which can be extrapolated from a bunch of photos.

In the mean time (!) here's a very approximate superimposition of the original airframe onto the previous photo:

http://i64.tinypic.com/2mmrur.jpg

@HundredPercentPlease
 

Parallel lines ... rudder departure scratch marks ?

Elevator hinges and THS appear less probable.

This requires measurements.

There is redundant set of actuators, and hinges, and ...

++
Options:
- Rudder 7-point attachment to the fin structure.
- Three rudder actuators - unlikely, too close, for a standalone scenario,
- Structural failure exposing CFRP stiffeners or brackets - might explain the close parallel lines.
- Structural failure exposing GFRP stiffeners or brackets - might explain the close parallel lines.

or a mix of these options,

++++
If you extend these lines downward you stay within the 'envelope' of the plane and reach the tailcone behind the aft firewall of the APU space. However, these components have been found and are unlikely to cause these parallel lines.
So the options you get is either a lower piece of structure breaking out of the VS, and rotating up relative to the VS box, such a part is missing. Or the CFRP strip or rudder departure. In each case you have to put the tail section tail down to get these marks. Which would suggest this is not the immediate cause but a follow up fracture.

++++++
The lower line is at about 12 degrees, the upper at about 15 degrees with the vertical ...

PersonFromPorlock wrote: With regard to the altitude errors I'll add this.
The baro altitude is sensed either side of the aircraft and converted to a digital signal within a few inches of the static ports for the Capt and FOs systems. In normal flight, both sides sense the same static pressure, it's converted to a digital signal and sent to the ADIRUs. The ADIRUs sum this received signal to generate the Capt and FOs altitude. (ADIRU 1 for Capt, ADIRU 2 for FO)

Since the signal is summed a large discrepancy in sensed pressures (or a failed ADM) will cause a corresponding altitude error. ie. If one side sensed 20000' and the other side 10000' the ADIRU would compute 15000' and display that.

I would suggest an airplane horrifically tumbling out of control would most probably generate these errors before electrical power was lost completely.

Different view of the parallel lines.

http://i.imgur.com/mrERkyI.png
http://i.imgur.com/dCsqxVT.png

Investigating a line of thought:

Can you operate the A321 with the APU running in the air to supply a generator (in the case of one generator inop?)

The line of thinking is that if the above is possible, what are the odds a catastrophic failure of the APU causing VS and HS damage to the point of them separating or controlling the steep climb?