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AF447

Old 8th Jun 2009, 21:08
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Now, now, children

MP, Will's punctuation makes it clear that the AFR PF was not in full control:

"As in AA587, the system "allowed" for too much travel, and the PF wasn't in tune with his a/c"

Except that's not what he meant, its just the way they speak in Petaluma.

He meant that the AAL pilot wasn't in tune....
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Old 8th Jun 2009, 21:10
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Dysag. thank you.
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Old 8th Jun 2009, 21:13
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ACARS Message

Captainflame
But the plane left Rio at 31 may, at 22:00 gmt so it seems that the
LAV CONT message were 45 mins after the liftoff - or maybe i dont get it.? Had to register to ask this, have looked at the event for some time now, what does it mean ?
FR0905312245 38310006vsc x2, ,,,,,LAV CONF

1 - The date stamp of the LAV CONF message is from the evening before (2245)
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Old 8th Jun 2009, 21:20
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Position of third pitot tube...

Interflug,

Acc. smartcockpit.com section Navigation 34.10 page 2, the third (STBY) pitot tube is located on the left side of the nose, close to capt. pitot tube.

bgds
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Old 8th Jun 2009, 21:22
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Just a point of distant data on vertical stabilizer breaks, the vast majority of a vs broke off a B52 in the US while flying thru rough summer weather at altitude around 1970. While they did complete their flight under the declaration of an emergency, they weren't aware how little vs they had remaining.

On AF447 I see nothing conclusive about how/when this one came off.
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Old 8th Jun 2009, 21:27
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CALENDESTIONO Post 654
"Oh, and IR needs TAS input to keep itself upright.:"
Are you sure this is correct?
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Old 8th Jun 2009, 21:36
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Rud Trv Lim

Gentlemen,

two cents regarding the loss of Rudder Travel Limiter, I stumbled upon a document which was put online by Eurocockpit - Accueil. The document in question relates to a pair of serious incidents with loss of pitot probes on A330s, company Air Caraïbes Atlantique (ACA). Makes for a fascinating reading (in French).

The ACA incident produces a series of failures that are strikingly similar to what is deduced from the ACARS document we use as foundation for study here.

Full document at http://www.eurocockpit.com/docs/ACA.pdf.
The document looks very solid from a technical point of view, full of nitty-gritty details, made after meetings between ACA people and AB people.

Back to RUD TRV LIM :

(Can't insert picture here... Anyway... Here is the gist of it, roughly)

As CAS becomes unavailable, maximum rudder deflection is 'frozen' (gelée) at about 10 degrees, however full rudder deflection will be recovered when SLATS are extended.

Since SLATS extension is purely mechanical (not linked to air data), we can reasonably conclude that a form of rudder limitation still exists (albeit a very primitive limitation, 10 degrees deflection) in the AF447 configuration.

Now is this 10 degrees limit useful in the situation ? At Mach 0.80 or so, would a full 10 degrees deflection be already too much for structure ?

Is the limit counterproductive ? I would like full deflection if I had to get out of a spin for example.
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Old 8th Jun 2009, 21:41
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Sosus

Hi. Ex Nav here. Sosus is gone, a casualty of the Clinton years. We now use towed passive arrays, which, if there was a vessel at sea, might have picked something up. Best regards.
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Old 8th Jun 2009, 21:49
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I have never driven an Airbus, but it has been mentioned on here that stick imputs from both sticks simultaneously in some Law conditions results in additive input (ie, if both sticks deflected left, input is doubled, if one left and one right, input is cancelled). Is this true? If so, does it hold for rudder inputs as well?
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Old 8th Jun 2009, 21:58
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ADVISORY pertaining to Air cond/pressurisation MODE Fault, seems to be linked to cab descent rate (unable to cope with a high VS descent to maintain required DIFF pressure !)
No point. As demonstrated, wrong air data from ADIRU are enough to trigger the actually transmitted advisory! Why is this a professional forum, when there is only media blurb considered and re-pasted? (Sorry to the guy from whom I took the quote above, does not mean any negative, just an example.)

But please all, read some posts here before re-posting wrong "findings".

What is the point that some posters even dig deeply into actual aircraft manuals and actual system definitions and / or contributing their actual hands-down experience, when their careful thoughts and findings are buried by meanigless chatter from worthless media repetitions?

Yes, could have been a steep descent, as it could have been anything by now, but you simply cannot conclude this from the ACARS data. (As well the often cited "TCAS antenna fail" is simply wrong, but posted over and over again.)

CALENDESTIONO Post 654
"Oh, and IR needs TAS input to keep itself upright.:"
That is of course incorrect. As this is intended to be a professional forum, please either inform yourself ahead of posting nonsense or ask this as a question.

Last edited by TripleBravo; 8th Jun 2009 at 22:08.
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Old 8th Jun 2009, 21:59
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Svarin in the fcom that I have it states the following:

Each (Rudder)limiter channel is controlled by its associated SEC.In case of a double SEC failure,the max rudder deflection stays at the value reached before the failure,then max deflection is available at slat extension.
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Old 8th Jun 2009, 22:12
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@ Steamcat

That is true... dual inputs from the sidesticks is not good to Fi-Fi
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Old 8th Jun 2009, 22:18
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Originally Posted by SteamCat
I have never driven an Airbus, but it has been mentioned on here that stick imputs from both sticks simultaneously in some Law conditions results in additive input (ie, if both sticks deflected left, input is doubled, if one left and one right, input is cancelled). Is this true? If so, does it hold for rudder inputs as well?
Side-stick inputs are summed, but limited to the maximum deflection of a single stick. E.g . in roll in normal law, maximum stick deflection demands 15 deg/sec roll rate. If both pilots make full left stick inputs, the demand is still only 15 deg/sec. One pilot making a full left, the other a half-right input, the result would be half-left.

Ruder pedals are different. They are mechanically linked and always control the rudder deflection directly (limited by the travel limiter).

(The rudder is also moved by the FBW system for turn coordination; I am not entirely sure FBW-commanded rudder movements are backdriven to the pedals.)


Bernd
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Old 8th Jun 2009, 22:38
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Acars

Interflug, correct me if i am wrong.
In my view ACARS is a "messaging system".
Not like a CFDS.
Or a QAR- recorder in parallel with the DFDR.
When ACARS tells you "probe-failure" it does not tell you, what probe fails.
Thats how it works on most airplanes.
My humble oppinion.
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Old 8th Jun 2009, 22:40
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Rud Limit

@Tubby:

I think Svarin is right, the report states:

la valeur maximale du debattement est gelee a 10°

the value of max rudder is frozen at 10°

You are right about the rest.

But this report of Air Caraibe shows the very same Ecam msgs and wrngs that were generated in the AF case, if one reads the ACARS msgs. Up to contradictorial informations to the Crew about Stall Wrng. The Cpt decided to ignore them as was written on an other part of the Tecn.Infos that those pilots used.

It is very interesting to read this report, seems to show a probable scenario.
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Old 8th Jun 2009, 22:40
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I think the rudder conversation is mostly just conversation; I doubt you can deduce much from speculating about the photos. The power of moving air is much greater than people realize—I've seen avalanches in the Canadian Rockies snap whole pine forests downslope like toothpicks: but in truth it was not the snow breaking those trees; it was the compressed air preceding the snow. The air by itself was snapping hundreds of tree-trunks in just a few seconds.

I think, whatever AF447 wreckage is found, the wreckage itself is likely a final result, and if you had half a dozen hypothetical scenarios which had similar causes, the way the plane fell—through such turbulence and from such a height—and what stayed together would vary considerably. Like any two leaves falling from a maple tree, I would suggest.
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Old 8th Jun 2009, 22:42
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The discussion on the VS implies a "breakaway line" or a fracture some distance from the attach points on the fuselage. I have taken a close look at the photos supplied earlier today and have enlarged one section, (lower, center) of one photograph to see if the structure in the middle of the photo is a mounting lug or if it is part of the recovery gear etc. I have inserted a photo of the AA587 fin lug for comparison.

I am not suggesting or concluding here but using the newly-available photos to examine further evidence of how the structure fractured. Although the alternatives are fairly limited, nor can we draw conclusions about how, when or why the vertical stabilizer is separated from the main structure. I am merely trying to identify a possible attach point to possibly address the partial failure suggestion seen a few posts back. PJ2.






Imageshack - vsertstablugdetailposco.jpg





...in "negative" form, for slightly better clarity:

Imageshack - vsertstablugdetailnegco.jpg


Last edited by PJ2; 8th Jun 2009 at 23:06.
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Old 8th Jun 2009, 22:45
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Yes, the VS tends to break at this point, but it is not "designed" to do so - it is simply the weakest point / link in the assembly.
Yes, that would be quite a design feature all right. Let's just let the tail fall off to save the rest of the aircraft!
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Old 8th Jun 2009, 22:54
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tail end first impact of intact a/c ?

I would concur with those posters theorising that the VS broke off in its entirety on impact and I would add: of a by and large intact a/c.

Looking at the VS photo's, I dare to argue that the a/c impacted more or less level flight, but at a very high AOA, making the very end of the tail section hit the water first, crunching the tail section upwards and in the process damaging the lower-edge of the rudder and unsettling the VS attachment. Subsequent impact of the main, more forward a/c sections would then arrest the forward movement of the VS to the point that it separates from the tail-section alltogether.

Just theorising on what material is available at present.
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Old 8th Jun 2009, 22:54
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I'm looking at the tail section right now, it seems surprisingly undamaged except for the rearmost section. If it were to "peel away" in the airflow, that's where I'd expect damage to be as it made contact with the empennage.

Question for those familiar with type, are all attachment points for the VS aft of the pressure bulkhead? I'm assuming they would be.
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