AF447
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That sideways force could have happened towards the beginning of the sequence (as in the AA A300 accident), or at the point the VS hit the water, or any point in between. Time will tell.
As a matter of fact, until we see the other side of the fin, evidence points towards a longitudinal breakage : the base of the rudder is broken, hinting at possible compression stresses, whereas the forward part of the fin base shows a more cleanly accomplished separation, this time indicative of tension forces.
With these observations, I could deduct that the moments that caused the fin to shear from the fuselage were directed aft, meaning the tail hit the water first ; an observation that could lead me to claim that either the fuselage broke in mid air in several parts or the entire aircraft was in a high pitch angle on impact...and still hit the sea tail first.
But of course, I won't make that kind of deduction for I'm one of those who would be very careful with too-quick conclusions and await further evidence.
Lemurian;
Yes, agree - we can only, possibly, say that there is a lug (or not) present in the photo.
There is nothing on those pictures that would tell you anything about "sideways forces"
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Lemurian;
Possibly in the chaos the trailing edge of the rudder met with the trailing edge of the HS or some other detached part.
Where are the rudder actuators attached to the rudder? Perhaps that section of the rudder was ripped off.
As a matter of fact, until we see the other side of the fin, evidence points towards a longitudinal breakage : the base of the rudder is broken, hinting at possible compression stresses,
Where are the rudder actuators attached to the rudder? Perhaps that section of the rudder was ripped off.
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Possibly in the chaos the trailing edge of the rudder met with the trailing edge of the HS or some other detached part.
Nowhere, I think.
Someone needs to summerize the factual infos avaikable, otherwise Danny will get back in with his big heavy boots.
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Vacuum System Controller Failure @ 2245
Re. abkasti's post # 721. I Would be grateful if somebody could comment on the significance or otherwise of the ACARS message that appears to have occurred 43 mins into the flight - the event with the timestamp 0905312245. Would this coincide with reaching cruise altitude? Understand this is a VSC Vacuum System Controller failure (FLR) with the message 'LAV CONF'. I recall my father telling me he was a passenger on an Indian Airlines A320 in the early nineties that had a cabin depressurisation and had to return to the departure airport - he had noticed early in the flight that the toilet flush was not functioning.
Lemurian,
As an engineer responsible for designing connections between steel components (and occasionally composite materials), I believe that I am well qualified to comment here.
Here's my reasoning:
The total force involved in breaking off the VS is pressure x area.
The frontal area of the VS is very, very small indeed (there's a reason for that - think about where you want as little drag as possible).
The lateral area of the VS is huge in comparison (there's a reason for that too, when you think about it).
So which of these is going to produce the larger total force?
Next, we move to the geometry of the connection to the fuselage. 2 lines of bolts running fore and aft, 3 bolts per line. The side to side distance is significantly less than the fore and aft distance, so the resisting moment is also far less.
In other words, the fore & aft moment is vastly smaller than the lateral moment, and the fore & aft resistance to failure is greater than the lateral resistance.
Believe me, if this were a fore & aft failure, there would be a huge dent in the VS that just isn't there.
FBW
There is nothing on those pictures that would tell you anything about "sideways forces"
As a matter of fact, until we see the other side of the fin, evidence points towards a longitudinal breakage : the base of the rudder is broken, hinting at possible compression stresses, whereas the forward part of the fin base shows a more cleanly accomplished separation, this time indicative of tension forces.
With these observations, I could deduct that the moments that caused the fin to shear from the fuselage were directed aft, meaning the tail hit the water first ; an observation that could lead me to claim that either the fuselage broke in mid air in several parts or the entire aircraft was in a high pitch angle on impact...and still hit the sea tail first.
As a matter of fact, until we see the other side of the fin, evidence points towards a longitudinal breakage : the base of the rudder is broken, hinting at possible compression stresses, whereas the forward part of the fin base shows a more cleanly accomplished separation, this time indicative of tension forces.
With these observations, I could deduct that the moments that caused the fin to shear from the fuselage were directed aft, meaning the tail hit the water first ; an observation that could lead me to claim that either the fuselage broke in mid air in several parts or the entire aircraft was in a high pitch angle on impact...and still hit the sea tail first.
Here's my reasoning:
The total force involved in breaking off the VS is pressure x area.
The frontal area of the VS is very, very small indeed (there's a reason for that - think about where you want as little drag as possible).
The lateral area of the VS is huge in comparison (there's a reason for that too, when you think about it).
So which of these is going to produce the larger total force?
Next, we move to the geometry of the connection to the fuselage. 2 lines of bolts running fore and aft, 3 bolts per line. The side to side distance is significantly less than the fore and aft distance, so the resisting moment is also far less.
In other words, the fore & aft moment is vastly smaller than the lateral moment, and the fore & aft resistance to failure is greater than the lateral resistance.
Believe me, if this were a fore & aft failure, there would be a huge dent in the VS that just isn't there.
FBW
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There is clear precedent for a VS being cleanly broken from an airframe by aerodynamic forces at altitude, and being recovered intact.
Is there precedent for a VS being so cleanly removed at root by impact? Most ways I can imagine in which such lateral force could be applied would tend to damage the fin.
Is there precedent for a VS being so cleanly removed at root by impact? Most ways I can imagine in which such lateral force could be applied would tend to damage the fin.
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In other words, the fore & aft moment is vastly smaller than the lateral moment, and the fore & aft resistance to failure is greater than the lateral resistance.
Believe me, if this were a fore & aft failure, there would be a huge dent in the VS that just isn't there.
Believe me, if this were a fore & aft failure, there would be a huge dent in the VS that just isn't there.
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FBW
http://www.pprune.org/4983708-post737.html
Not if you would consider the scenario put frwd in my previous post.
I agree however with PJ2 and others that there are several theories possible. To underline that was at least my implicit intention of my post a couple of pages back, to counter the theories floated by other posters arguing parallels with the A300 accident hardrudder accident.
Not if you would consider the scenario put frwd in my previous post.
I agree however with PJ2 and others that there are several theories possible. To underline that was at least my implicit intention of my post a couple of pages back, to counter the theories floated by other posters arguing parallels with the A300 accident hardrudder accident.
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FBW, fair enough, but you have to assume first that you have a lateral moment, or why should it break sideways if the moment is fore and aft ?
Further more, IF we assume only accelerations and not aerodynamic stresses, most of your argument goes down the drain, leaving us to guess at where the structure failed.
Mind you, I would tend to agree with an in-flight break-up and lateral streesses on the vertical fin, I'm just playing the devil's advocate for the sake of prudence.
Further more, IF we assume only accelerations and not aerodynamic stresses, most of your argument goes down the drain, leaving us to guess at where the structure failed.
Mind you, I would tend to agree with an in-flight break-up and lateral streesses on the vertical fin, I'm just playing the devil's advocate for the sake of prudence.
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A translated letter from a TransAtlantic pilot:
"My friends....I have a theory re possible causes of the Airbus Air France Crash, and it is based on my own experiences.
The Met phenomenon which happened to me was in the general area of the Air France crash, in May 2001, when I was returning to Spain from Buenos Aires in a B743. From overhead Rio, we followed the exact same route as the Air France Airbus, and passing the area of the accident crossing the Intertropical Front at F370, we found moderate to severe turbulence. For around 1 to 2 minutes of the flight we then experienced a sudden increase of outside air temperature, it went from -48C to -19C.
As a result of this temperature discrepancy, we went from flying with a margin of 10,000Kgs to 15,000kgs outside the flight envelope for that flight level, and the aeroplane started an immediate pitch down, with very strong oscillations. I disconnected the Autopilot and we descended, losing 4,000Ft...we were well in the "Coffin Corner", and I am certain had we not disconnected the Autopilot and regained control of the descent, we might be at the bottom of the Atlantic ourselves, as the Autopilot would have tried to maintain altitude and would not have been possible. I have since been flying an A340 in those routes and have not found the same conditions since, which in my 40 years flying I had never ever considered possible. I would describe it as a massive funnel of 40NM in diameter of incredibly warm air with an embedded CB rising at extremely fast rate...after 5 minutes of flying by the seat of our pants, everything started to get back to normal, temp went back to 048C and I was able to regain climb back to F370.
Airbus advises not to disconnect the Autopilot when entering Turbulence, but a situation like the one I described has not been documented before that I am aware of."
"My friends....I have a theory re possible causes of the Airbus Air France Crash, and it is based on my own experiences.
The Met phenomenon which happened to me was in the general area of the Air France crash, in May 2001, when I was returning to Spain from Buenos Aires in a B743. From overhead Rio, we followed the exact same route as the Air France Airbus, and passing the area of the accident crossing the Intertropical Front at F370, we found moderate to severe turbulence. For around 1 to 2 minutes of the flight we then experienced a sudden increase of outside air temperature, it went from -48C to -19C.
As a result of this temperature discrepancy, we went from flying with a margin of 10,000Kgs to 15,000kgs outside the flight envelope for that flight level, and the aeroplane started an immediate pitch down, with very strong oscillations. I disconnected the Autopilot and we descended, losing 4,000Ft...we were well in the "Coffin Corner", and I am certain had we not disconnected the Autopilot and regained control of the descent, we might be at the bottom of the Atlantic ourselves, as the Autopilot would have tried to maintain altitude and would not have been possible. I have since been flying an A340 in those routes and have not found the same conditions since, which in my 40 years flying I had never ever considered possible. I would describe it as a massive funnel of 40NM in diameter of incredibly warm air with an embedded CB rising at extremely fast rate...after 5 minutes of flying by the seat of our pants, everything started to get back to normal, temp went back to 048C and I was able to regain climb back to F370.
Airbus advises not to disconnect the Autopilot when entering Turbulence, but a situation like the one I described has not been documented before that I am aware of."
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Looking at the pictures posted by PJ2 and the pictures on the brasillian website, it does look like there is a lug attached to some ribbed box structure. The A330 has 3 groups of attachment points for the VS, judging by the relative location, this would appear to be the middle one.
Is anyone able to identify this "box" structure from the photograph?
Is anyone able to identify this "box" structure from the photograph?
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Lemurian:
Ok,I'm with you.
Not quite so complicated if the aircraft was in a spin when it hit. For a brief moment the VS attach junction had to carry increased forces and after failure that rudder section could've been damaged like that.
Yes, like you I only see a number of possibilities and not so inclined to propose what DID happen.
Don' put words in my typing : My post was just about too-quick interpretations and conclusions and the remarks I made were another possibility
so between the posters who see a sideways breakage, and you proposing a far more complicated scenario, where do we stand ?
Yes, like you I only see a number of possibilities and not so inclined to propose what DID happen.
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For AB Engineering/training/experienced and knowledgeable people
1. What is the maximum rudder deflection (degrees) available for low speed op's (such as asymmetrics)?
2. What is the limited (NORMAL law) maximum rudder deflection (degrees) available at high altitudes at normal cruise type speeds?
3. Is pedal deflection (when rudder limiter is operational, NORMAL law) designed to be the same foot feel (travel in inches/centimetres) across the entire speed envelope?
4. Is pedal deflection (when rudder limit is 10 degrees, ALTN or DIRECT law) the same foot feel (travel in inches/centimetres) as NORMAL law?
The questions are asked without implication or speculation, rather to understand IF degraded control protections might have an impact on high altitude, high speed upset recovery control inputs verses control surface outputs.
Thankyou
1. What is the maximum rudder deflection (degrees) available for low speed op's (such as asymmetrics)?
2. What is the limited (NORMAL law) maximum rudder deflection (degrees) available at high altitudes at normal cruise type speeds?
3. Is pedal deflection (when rudder limiter is operational, NORMAL law) designed to be the same foot feel (travel in inches/centimetres) across the entire speed envelope?
4. Is pedal deflection (when rudder limit is 10 degrees, ALTN or DIRECT law) the same foot feel (travel in inches/centimetres) as NORMAL law?
The questions are asked without implication or speculation, rather to understand IF degraded control protections might have an impact on high altitude, high speed upset recovery control inputs verses control surface outputs.
Thankyou
FDR
During the tail strike of the A345 in Melbourne in March this year, the flight data recorder was dislodged from its bracket.
There is a picture of the bracket on page 20 of the ATSB report. http://www.atsb.gov.au/publications/...012_Prelim.pdf
Does Airbus designed FDRs to seperate from the fuselage during a crash?
If so, is this based on a rational that the location beacon works better when the recorder is not surrounded by metal?
Mickjoebill
There is a picture of the bracket on page 20 of the ATSB report. http://www.atsb.gov.au/publications/...012_Prelim.pdf
Does Airbus designed FDRs to seperate from the fuselage during a crash?
If so, is this based on a rational that the location beacon works better when the recorder is not surrounded by metal?
Mickjoebill
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puzzled
I'm puzzled by the "crew rest" part.
http://www.fab.mil.br/portal/voo447/...609/foto_2.JPG
Taking into account the letter "E" in front of CR, I gather that it is a part of the perpendicular side of a mobile rest area the size of an LD6 container. Am I right to suppose that in a 330 this is normally situated just aft of the wings section ?
I couldn't find another 330 example, but here is a LH 340 one to indicate what it should look like:
Photos: Airbus A340-313X Aircraft Pictures | Airliners.net
http://www.fab.mil.br/portal/voo447/...609/foto_2.JPG
Taking into account the letter "E" in front of CR, I gather that it is a part of the perpendicular side of a mobile rest area the size of an LD6 container. Am I right to suppose that in a 330 this is normally situated just aft of the wings section ?
I couldn't find another 330 example, but here is a LH 340 one to indicate what it should look like:
Photos: Airbus A340-313X Aircraft Pictures | Airliners.net
Sorry if this has been repeated, but I can only read so much in so little time I have as an engineer ... 
QUESTION: Does it seem like the fuselage fell out of the sky completely intact, as there is very little wreckage or rubble floating on the surface, only large components/interior parts that have risne from the bottom where a tear is maybe in the fuselage??
Also it may seem to me, that very few bodies have been found (17 I've just heard on the news) due to they were all strapped in during the turbulence. Maybe answering my own question, but it seems that it lost control, entered a vertical profile downward, entered the water like a missile, and reached the sea floor. (not speculating, but I have to investigate the facts all the time to make a correct maintenance decision). The fact that little wreckage is evident is due to probably a pin drop impact, and not a belly-whacker impact seperating aircraft fairings and parts & baggage everywhere. AGREE? Just asking??
Also, from working in the EMS & SAR industry, and searching for bodies myself in the past, it is a known fact that a human body that drowns will sink for the first 3 days, and then rise to the surface after that when the acids reflux and create air bubbles, and bloat the liquid cells under the skin, and cause the body to float. ... Not to grouse you out, but hopefully many more bodies will be recovered in the next few days, as they float, so that families can have closure & bury their loved ones, and be at rest.
Maybe the impact was enough to knock many unconscious, and many have drowned still in their seatbelts. Having investigated and been involved in EMS/SAR roles, I do see that there is little to be found that gives rock evidence, but this little info gives clearer information that it was sudden & quick, not a massive explosion or break-up at all due little recovered parts. The way the vertical fin broke off will give many answers as to the side load forces or G-forces that tore it off.
KP
QUESTION: Does it seem like the fuselage fell out of the sky completely intact, as there is very little wreckage or rubble floating on the surface, only large components/interior parts that have risne from the bottom where a tear is maybe in the fuselage??
Also it may seem to me, that very few bodies have been found (17 I've just heard on the news) due to they were all strapped in during the turbulence. Maybe answering my own question, but it seems that it lost control, entered a vertical profile downward, entered the water like a missile, and reached the sea floor. (not speculating, but I have to investigate the facts all the time to make a correct maintenance decision). The fact that little wreckage is evident is due to probably a pin drop impact, and not a belly-whacker impact seperating aircraft fairings and parts & baggage everywhere. AGREE? Just asking??
Also, from working in the EMS & SAR industry, and searching for bodies myself in the past, it is a known fact that a human body that drowns will sink for the first 3 days, and then rise to the surface after that when the acids reflux and create air bubbles, and bloat the liquid cells under the skin, and cause the body to float. ... Not to grouse you out, but hopefully many more bodies will be recovered in the next few days, as they float, so that families can have closure & bury their loved ones, and be at rest.
Maybe the impact was enough to knock many unconscious, and many have drowned still in their seatbelts. Having investigated and been involved in EMS/SAR roles, I do see that there is little to be found that gives rock evidence, but this little info gives clearer information that it was sudden & quick, not a massive explosion or break-up at all due little recovered parts. The way the vertical fin broke off will give many answers as to the side load forces or G-forces that tore it off.
KP