BREAKING NEWS: airliner missing within Egyptian FIR
How far apart are the rudder attachment fixings on the VS? (anyone got a spare A321 hanging about and could grab a ladder?)
ETA: Looking at Sardak's post I think it's clear there are some more funny camera effects going on, and it isn't paint loss at all, and is related to internal structure as suggested earlier.
Sorry for wasting time.
ETA: Looking at Sardak's post I think it's clear there are some more funny camera effects going on, and it isn't paint loss at all, and is related to internal structure as suggested earlier.
Sorry for wasting time.
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VS image puncture & scratch marks
On the VS image near the bottom left of the blue paint looks like an entry hole, with white paint removed and primer or raw metal showing.
Horizontally above the door the left end of the scratch-like mark coincides with the concave turn in the fuselage yet strangely does not pass across it.
A challenge to discern the causes?
Horizontally above the door the left end of the scratch-like mark coincides with the concave turn in the fuselage yet strangely does not pass across it.
A challenge to discern the causes?
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@Yankee Whiskey:
Practically every big jet ever made lacks pitch trim tabs. Instead, they trim by changing the angle of the horizontal stabilizers to the fuselage. That's the function of that jackscrew people keep banging on about...
@susier:
Those parallel scrape marks on the vertical stabilizer are intriguing .... indebted to you for noticing and pointing them out. I struggle to imagine how they came to be, in combination with the stabilizer being so grotesquely fractured.
A0283's notion of the departing rudder makes a lot of sense. But what does it mean, that the slipstream was (presumably) at that angle with respect to the stabilizer? Were the marks made while the vertical stabilizer was still in its normal relation to the aft-most fuselage, or after the fracture?
Whatever story the empennage is trying to tell us, its condition surely bears witness to the intense extremity of the circumstances that ensued once the airframe began its breakup. Dreadful to contemplate.
____________________
Edited to add:
The long parallel scrape marks don't resemble any photographic artifact I am familiar with. I am confident that they accurately indicate the surface condition of the vertical stabilizer. Anyway, they are clearly visible in photographs taken from different perspectives -- the camera didn't make them.
I don't know what the inside of the A321 VS looks like, but typically the internal structural elements are nearly parallel to the long axis of the (tilted aft from vertical in the normal orientation of the VS), and more or less at right angles to that (horizontal in the normal orientation). If an aerostructure isn't built in this manner, it is likely to be needlessly heavy (for a given level of stiffness and ultimate strength). I don't see how it would be structurally efficient to have elements at the angles of the scrape marks.
I have tried and tried, but I am unable to visually correlate the photos recently posted by sardak with the photos showing the long parallel scrapes (which are farther aft in normal orientation, than the area shown in the sardak close-ups).
Practically every big jet ever made lacks pitch trim tabs. Instead, they trim by changing the angle of the horizontal stabilizers to the fuselage. That's the function of that jackscrew people keep banging on about...
@susier:
Those parallel scrape marks on the vertical stabilizer are intriguing .... indebted to you for noticing and pointing them out. I struggle to imagine how they came to be, in combination with the stabilizer being so grotesquely fractured.
A0283's notion of the departing rudder makes a lot of sense. But what does it mean, that the slipstream was (presumably) at that angle with respect to the stabilizer? Were the marks made while the vertical stabilizer was still in its normal relation to the aft-most fuselage, or after the fracture?
Whatever story the empennage is trying to tell us, its condition surely bears witness to the intense extremity of the circumstances that ensued once the airframe began its breakup. Dreadful to contemplate.
____________________
Edited to add:
The long parallel scrape marks don't resemble any photographic artifact I am familiar with. I am confident that they accurately indicate the surface condition of the vertical stabilizer. Anyway, they are clearly visible in photographs taken from different perspectives -- the camera didn't make them.
I don't know what the inside of the A321 VS looks like, but typically the internal structural elements are nearly parallel to the long axis of the (tilted aft from vertical in the normal orientation of the VS), and more or less at right angles to that (horizontal in the normal orientation). If an aerostructure isn't built in this manner, it is likely to be needlessly heavy (for a given level of stiffness and ultimate strength). I don't see how it would be structurally efficient to have elements at the angles of the scrape marks.
I have tried and tried, but I am unable to visually correlate the photos recently posted by sardak with the photos showing the long parallel scrapes (which are farther aft in normal orientation, than the area shown in the sardak close-ups).
Last edited by Etud_lAvia; 9th Nov 2015 at 18:49.
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Has anyone considered the following scenarios:
Explosion destroys Fly By Wire signals to elevator and rudder, causing control surface run away to extreme travels, resulting in structural failure of the empennage due to huge aero loads.
or
Hydraulic lines are severed to elevator and rudder servos, loss of pressure allows the control surfaces to flutter, as they are now not held "stiff" relative to the HS and VS. Remember that these surfaces are not mass balanced, relying on hydraulic actuators to prevent flutter.
Or a combination of the above?
Notice that both elevators and the rudder came off, suggesting flutter. Elevator flutter would also be a reason to lose the HS halves as happened.
Explosion destroys Fly By Wire signals to elevator and rudder, causing control surface run away to extreme travels, resulting in structural failure of the empennage due to huge aero loads.
or
Hydraulic lines are severed to elevator and rudder servos, loss of pressure allows the control surfaces to flutter, as they are now not held "stiff" relative to the HS and VS. Remember that these surfaces are not mass balanced, relying on hydraulic actuators to prevent flutter.
Or a combination of the above?
Notice that both elevators and the rudder came off, suggesting flutter. Elevator flutter would also be a reason to lose the HS halves as happened.
The lines can be seen here in this link provided earlier by Mitrosft:
? ???? ? ? ????? ?? ???? ????????... - ???????? ???????
? ???? ? ? ????? ?? ???? ????????... - ???????? ???????
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re cvr and fdr
#1924 (permalink)
One earlier photo of the CVR was such that the label with a little magnifaction clearly spelled out solid state memory cockpit voice recorder
see
http://www.pprune.org/rumours-news/5...ml#post9168948
note the mangled attach points and a split in the lower orange mounting ' tray'
now look at
http://www.pprune.org/rumours-news/5...ml#post9169622
to determine how and where it was mounted compared to the FDR ( which mounted different but above and with a badly bent ' tray " in the hands of ?? as shown in
http://www.pprune.org/rumours-news/5...ml#post9165152
but no obvious ( in this view ) aluminum colored tray or attached framework.
Which is why I think that same section hit the ground with CVR still ' installed" and was taken away before press access
IMO damage to CVR and FDR was most likely from impact with ground while attached to a heavy object such as HS wing box and jackscrew brackets, etc.
One earlier photo of the CVR was such that the label with a little magnifaction clearly spelled out solid state memory cockpit voice recorder
see
http://www.pprune.org/rumours-news/5...ml#post9168948
note the mangled attach points and a split in the lower orange mounting ' tray'
now look at
http://www.pprune.org/rumours-news/5...ml#post9169622
to determine how and where it was mounted compared to the FDR ( which mounted different but above and with a badly bent ' tray " in the hands of ?? as shown in
http://www.pprune.org/rumours-news/5...ml#post9165152
but no obvious ( in this view ) aluminum colored tray or attached framework.
Which is why I think that same section hit the ground with CVR still ' installed" and was taken away before press access
IMO damage to CVR and FDR was most likely from impact with ground while attached to a heavy object such as HS wing box and jackscrew brackets, etc.
Initially on seeing the tailplane missing from the tailcone and the skin below the tailplane ripped out, the most likely explanation seemed the jackscrew parting company with the tailplane leading to the tailplane pivoting down and being torn out by aerodynamic forces.
But we now have both exterior halves of the tailplane with so far no joining structure (likely containing jackscrew and hinge mounts).
Given the abrupt cessation of data to the FDR and CVR, perhaps the same event (explosive or structural) severed data buses and/or hydraulics, pneumatics etc for the flight controls, which then overloaded themselves.
But we now have both exterior halves of the tailplane with so far no joining structure (likely containing jackscrew and hinge mounts).
Given the abrupt cessation of data to the FDR and CVR, perhaps the same event (explosive or structural) severed data buses and/or hydraulics, pneumatics etc for the flight controls, which then overloaded themselves.
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re hydraulic-FBW failures
#1949 (permalink)
problem with both electrical and or loss of hydraulic.
Your comment would be correcct IF hydraulic clyinders were directly used to position HS. BUT both systems drive motors which turn the jackscrew
Any cutting of wires or hydraulic lines would simply leave the jackscrew non moveable by rotation, and absent other issues HS would stay in place.
Hydraulic lines are severed to elevator and rudder servos, loss of pressure allows the control surfaces to flutter, as they are now not held "stiff" relative to the HS and VS. Remember that these surfaces are not mass balanced, relying on hydraulic actuators to prevent flutter.
Your comment would be correcct IF hydraulic clyinders were directly used to position HS. BUT both systems drive motors which turn the jackscrew
Any cutting of wires or hydraulic lines would simply leave the jackscrew non moveable by rotation, and absent other issues HS would stay in place.
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Last edited by Bertie Bonkers; 9th Nov 2015 at 19:52. Reason: Add image
RE HS and Rudder servo?
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The VS scrape marks aren't visible in this photo.
http://www.pprune.org/rumours-news/5...ml#post9174686
http://www.pprune.org/rumours-news/5...ml#post9174686
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CVRs/FDRs can come in different shapes/sizes. The CVRs I worked with were in standard oblong boxes, same external shape and size as many of the other avionic boxes, except they were painted Yellow/orange. The crash-fire-proof container for the tape (it was a long time ago) was inside. Only the pinger was visible, being mounted outside on the back.
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@Orestes:
Interesting! The long parallel marks are not visible at all in the photo to which you linked ... but very clearly visible in more than one photo, including this one from susier.
It seems to me that the crucial difference among these images, is that yours (the one showing no marks) is some combination of the perspective angle, and the position of the sun when the photo was taken.
The images showing the marks have brightly highlighted regions, in which the surface is reflecting the sun toward the camera. The image to which you linked is "flat" in terms of illumination: no strong highlights.
On this basis, my interpretation is that the marks are NOT paint scrapes, but rather contours in the VS skin (presumably furrows, but possibly ridges). This would explain why they don't show under different light angles.
If these are skin contour marks, then I suppose they might be the consequence of either:
(a) object(s) indenting the skin (but not removing the paint) as they flew past
or
(b) wrinkling of the skin, perhaps due to extraordinary deformation under the forces of the calamity
Somehow, (b) seems more probable. I've seen a number of examples of skin wrinkling on old non-pressurized planes, which didn't look anything like the patterns on the VS. But the fuselage skin on those old birds was mainly there to keep the wind out, and the construction of an A321 stabilizer is a world apart.
Interesting! The long parallel marks are not visible at all in the photo to which you linked ... but very clearly visible in more than one photo, including this one from susier.
It seems to me that the crucial difference among these images, is that yours (the one showing no marks) is some combination of the perspective angle, and the position of the sun when the photo was taken.
The images showing the marks have brightly highlighted regions, in which the surface is reflecting the sun toward the camera. The image to which you linked is "flat" in terms of illumination: no strong highlights.
On this basis, my interpretation is that the marks are NOT paint scrapes, but rather contours in the VS skin (presumably furrows, but possibly ridges). This would explain why they don't show under different light angles.
If these are skin contour marks, then I suppose they might be the consequence of either:
(a) object(s) indenting the skin (but not removing the paint) as they flew past
or
(b) wrinkling of the skin, perhaps due to extraordinary deformation under the forces of the calamity
Somehow, (b) seems more probable. I've seen a number of examples of skin wrinkling on old non-pressurized planes, which didn't look anything like the patterns on the VS. But the fuselage skin on those old birds was mainly there to keep the wind out, and the construction of an A321 stabilizer is a world apart.
Last edited by Etud_lAvia; 9th Nov 2015 at 20:33. Reason: wording
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More so than I realised - this is what threw me (I won't embed the pic because it's 1300px wide):
http://www.fineksaviation.com/images...0all%20FDR.jpg
Second from left is a CVR, third from left is FDR - it's all in the length.
http://www.fineksaviation.com/images...0all%20FDR.jpg
Second from left is a CVR, third from left is FDR - it's all in the length.
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@CONSO:
The jackscrew (moving the entire horizontal stabilizer) makes slow / large changes of pitch moment, essentially for trim.
The hydraulically actuated elevator surfaces make fast / smaller changes of pitch moment for control of airspeed and flight path.
Jet transports have very broad CG limits. They can also experience changes of pitch moments with airspeed variation (mach number effects) and flap operation. For these reasons, they need the gigantic pitch authority provided by the movable HS.
The jackscrew (moving the entire horizontal stabilizer) makes slow / large changes of pitch moment, essentially for trim.
The hydraulically actuated elevator surfaces make fast / smaller changes of pitch moment for control of airspeed and flight path.
Jet transports have very broad CG limits. They can also experience changes of pitch moments with airspeed variation (mach number effects) and flap operation. For these reasons, they need the gigantic pitch authority provided by the movable HS.
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I also asked the make up of the investigation team. So I'll I try asking again, can anyone tell me the make up of the investigation team?
Egyptian (ECAA)--because it landed in their territory
French (BEA)--because it was their plane.
I assume BEA will mostly be doing consulting. I suspect MAK will lead it if for no other reason than the Egyptians have no technical ability to handle the task. Of course, the last time that happened we had the Flight 990 fiasco...
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Russian (MAK)--because it was their citizens and their flight.
Egyptian (ECAA)--because it landed in their territory
French (BEA)--because it was their plane.
Egyptian (ECAA)--because it landed in their territory
French (BEA)--because it was their plane.
I heard about German team also - because of engines.
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CVR with explosive decompression
Someone asked if an explosive decompression would be heard on the CVR. I think CAL611 is relevant to Metrojet 7K9268. This is an image of it's CVR which was explosive decompression from tailstrike repair metal fatigue.
SRC:
http://www.fss.aero/accident-reports...2-05-25-TW.pdf
SRC:
http://www.fss.aero/accident-reports...2-05-25-TW.pdf
