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AF447 wreckage found

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AF447 wreckage found

Old 22nd Jul 2011, 17:22
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Originally Posted by Bearfoil
So IF the Horizontal Stabiliser was not connected to its jackscrew (which "Positions it internally"), it would deflect to whichever angle the elevators put it. This would in turn change the Pitch of the a/c, but opposite to ss input. Down elevator pushes the trailing edge of the HS UP, climbing the a/c.
Hence, following your own logic, with all those sustained nose up imputs recorded, this aircraft would not stall at the first place... as she would dive straight into the sea!
Beside, there isn't one but three drive systems working the THS actuator : one electrical, one hydraulical, and one mechanical... all of them have anti-jamming devices avoiding that THS actuator could get free in case of whatever imaginatory undetected failure you might be thinking about. It is quite a big screw planted into the tail and quite a big piece of steel surmounting it.

Last edited by takata; 22nd Jul 2011 at 17:33.
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Old 22nd Jul 2011, 18:27
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As I read the system diagram, you won't be able to move the THS inflight without hydraulic pressure.

The mechanical link interacts with the hydraulic motor (jack?) to move the THS up or down via the trim wheel commands.

Hydraulic motors from blue and/or yellow hydraulic systems power the jack.

If the electrical controls are still working (as one would expcet in Alternate Law) an electric motor tells the hydraulic motor/jack which way to move, and how much. (Notation a few posts up on damping appreciated, I finally "got" how that works in normal operations).

If I misunderstand what moves the THS, I'd appreciate any corrections so I can annotate my slides.
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Old 22nd Jul 2011, 18:42
  #2143 (permalink)  
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I think trim wheel and EFCS power the THS similarly, but via different inputs?

The damper Hyd Motor, and the actuator motor are on the same screw (per machaca's pic). My understanding is that they can alternate roles.

The Elevators are independent of one another, obviously, there is no through hull penetration for an elevator "spar". Each hangs off the TE of the HS.

The HS is attached to a continuous spar, making each leaf a part of the solid slab.

I do not know if the elevators deflect independently, (Roll?).

I cannot 'copy' my tail innards pic. It's in here somewhere, sorry.
 
Old 22nd Jul 2011, 20:14
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THS - Screw Jack

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Old 22nd Jul 2011, 21:17
  #2145 (permalink)  
 
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Cool

Hi,

Thunder and lightning comments are IMHO of less merit. The primary threat here is convection (up/down draft, shearing resulting in excessive strain to the airframe and disruption to flight path/attitude) and precipitation (causing icing on the airframe and affecting thrust). Lightning can occur many miles away from the convective storm and can be independent event. Lightning strike on a/c is a very rare and generally benign event.
Ironically .. the thunderstorm thingy was the first words tell by Gourgeon (AF CO) at first press meeting as explainations after AF447 crash.
This was immediately dismissed by some experts as a cause of the crash...
Certainly some had an agenda .. but who ?
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Old 22nd Jul 2011, 22:24
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Hopefully soon we will get a final report from BEA to make this an informative thread again. It has drifted into oblivion recently. Most everything brought up recently goes against the keep it simple rule. We know they had UAS and they crashed. Jackscrews, thunderstorms, severe updrafts and triple attitude indicator failures are really reaching.
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Old 23rd Jul 2011, 01:16
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jcjeant

Hi,

Quote:
Thunder and lightning comments are IMHO of less merit. The primary threat here is convection (up/down draft, shearing resulting in excessive strain to the airframe and disruption to flight path/attitude) and precipitation (causing icing on the airframe and affecting thrust). Lightning can occur many miles away from the convective storm and can be independent event. Lightning strike on a/c is a very rare and generally benign event.
"Ironically .. the thunderstorm thingy was the first words tell by Gourgeon (AF CO) at first press meeting as explainations after AF447 crash.
This was immediately dismissed by some experts as a cause of the crash...
Certainly some had an agenda .. but who ? "

Allow me to speculate: If every airline in the world had a policy stating that Avoiding Thunderstorms was the prudent thing to do, and AF did not -- then I feel confidant that they would dismiss it as a Probable or Contributing cause factor. Especially since they have no more proof as to the real Probable Cause than we do.

Last edited by wallybird7; 23rd Jul 2011 at 01:19. Reason: Title
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Old 23rd Jul 2011, 05:22
  #2148 (permalink)  
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Quoting BOAC:-

The climb is still unexplained.
Came across this article quoting an Airbus pilot at some length. It offers a (pretty hair-raising) explanation of what MAY have happened. Obviously there's no way I can 'authenticate' it - and I didn't try to delete the expletives! - but I hope it's of interest.

An Airbus Captainís Take on the Air France Disaster | Autopia | Wired.com
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Old 23rd Jul 2011, 06:07
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It's right on target!

Totally agree!
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Old 23rd Jul 2011, 06:08
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...One or the other or both of the cockpit crew wanted the Captain's presence, NOW. It could not have been UAS, Weather, or any of the normal suspects, imho.
Some one removed his bars (figuratively), placed them on the deck, and called for help from Captain. It is not in the nature of Pilots to do that, unless the situation is irrecoverable. Such as, an aircraft that is behaving wildly, unpredictably, and deadly.
...or you are following previous orders to be called back if the situation calls for it. Remeber we are taking about French plane with all French crew following clearly set 'power index' rules.

if PF knows that the situation is irrecoverable than CRM would require him to voice it and communicate with the PNF - the trace of such behaviour is when the plane has practically already fallen out of othe sky at 2:13:47 ie some 40 sec before impact.
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Old 23rd Jul 2011, 06:55
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Came across this article quoting an Airbus pilot at some length. It offers a (pretty hair-raising) explanation of what MAY have happened.
The key ingredient most everyone seems to be overlooking: The flight control laws of an Airbus.
Yes, exactly, maybe he should look them up.
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Old 23rd Jul 2011, 09:13
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Editorís note: Air France Flight 447 was en route to Paris from Rio de Janeiro when it went down over the Atlantic Ocean on June 1, 2009, killing all 228 people aboard. It took 11 months to locate the Airbus A330-200ís black box data recorders
Their standard of editing reflects the standard of the article.....June 2009 until May 2011 looks a lot more like 23 months !
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Old 23rd Jul 2011, 18:47
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Originally Posted by RWA
Quoting BOAC:-

Came across this article quoting an Airbus pilot at some length. It offers a (pretty hair-raising) explanation of what MAY have happened. Obviously there's no way I can 'authenticate' it - and I didn't try to delete the expletives! - but I hope it's of interest.

An Airbus Captainís Take on the Air France Disaster | Autopia | Wired.com
Hello there,
I understand the risk underlined in the above Wired article:
- both the Pitot ram tube and its drain freeze, hence the airspeed derived from this compromised Pitot becomes an increasing function of the altitude,
- the flight enveloppe protection laws tend to increase the altitude if the airspeed increases too much
... and the interaction between these two phenomena makes a diverging control loop (if there is an altitude perturbation, say an increase, the airspeed increases too and the protection law commands an increase of altitude, etc...)

But in the AF 447 case:
- the early left PFD and the ISIS airspeeds inconsistency was only 1 min and the flawed airspeed does not seem overestimated but largely underestimated
- the flight protections (high speed prot) are lost in ALT2 triggered by a NAV disagreement
- the maintained NU inputs are the PF inputs

So how the Wired hypothesis can be applied to the AF 447 case ?
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Old 23rd Jul 2011, 18:54
  #2154 (permalink)  
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So, the a/c compensates in control of the airframe. But in reading (computing) altitude, doesn't it rely on a/s (as well as Statics).

How does the BEA harvest "altitude" information? Is it reliable? (The altitude, not BEA, sorry).
 
Old 23rd Jul 2011, 20:49
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Bubbers44
"W7 you seem warped"

How so?
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Old 23rd Jul 2011, 22:40
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"Whether the aircraft was struck is the main item of concern, and it appears no such event occurred."

All that refers to is the fact that the plane was probably not struck by lightning.



It still confirms the fact that strong updrafts were probable as well as turbulence and that alone was enough to cause the pilots to lose control of the airplane. Which they did.


I guess a stream of irrational posts like this inspired warped. No data, just personal opinion. We would be losing aircraft every day if your statement was true.
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Old 24th Jul 2011, 00:46
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Hello there,
I understand the risk underlined in the above Wired article:
- both the Pitot ram tube and its drain freeze, hence the airspeed derived from this compromised Pitot becomes an increasing function of the altitude,
- the flight enveloppe protection laws tend to increase the altitude if the airspeed increases too much
... and the interaction between these two phenomena makes a diverging control loop (if there is an altitude perturbation, say an increase, the airspeed increases too and the protection law commands an increase of altitude, etc...)

But in the AF 447 case:

- the early left PFD and the ISIS airspeeds inconsistency was only 1 min and the flawed airspeed does not seem overestimated but largely underestimated
- the flight protections (high speed prot) are lost in ALT2 triggered by a NAV disagreement
- the maintained NU inputs are the PF inputs

So how the Wired hypothesis can be applied to the AF 447 case ?

Hi Hyperveloce,

Yes, on reading the article I agree with your comments. The aircraft was not climbing prior to Alternate Law, and all subsequent NU inputs were from the PF's controls (that's pretty clear from the BEA report).

It worries me that this guy is (supposedly) a captain, he appears to have less understanding of this case than many of the 'punters' he openly dismisses.
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Old 24th Jul 2011, 01:29
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Remember the Captain (PF) of Q32 describing "explosions" in #2? Bad form, we were told they were to be called "bursts". Is he less a Captain?

I haven't a clue if this Captain (wired) is a Captain, or Jimmy Hoffa. He sounds legit, but then "they" would want him to act that way?

Wired's theory is spit simple that of The Shadow, who hung around a bit like Captain Burkill on BA038. Are they the same "Captain"? I'd say no, there are perhaps six main theories and several sub theories that sound one to the next acceptable.

Bad weather, a fact. (Watch someone demand a definition of "bad").
Iffy Pitot Probes, a fact. (Hollywood couldn't make this up.)
Night time. (Demonstrable, and no Horizon? just a guess).
UAS. Not a fact, but most likely? It has its own name, so it must be important, but not important enough to qualify Thales for an AD. (Fact).
No speeds to speak of, and PF caught the a/c as a bit of a surprise, (thought to be a fact). He moved the stick, contra the suggested procedure offered by PJ2, whose input here is the Gold Standard.
An absurd and deadly climb of 3000 feet ending in a relatively (almost) recovered airframe, but instead she squats down and does the mush for seven miles.

This is all pretty true, I think. I am told the Judge has sequestered all evidence produced by BEA; it is simply not going to be produced. (Rumor)

Sounds unlike a group whose goal is the TRUTH, and SAFETY. It can't be important, or they would make it public, or order some procedural hoorahs, yes! So, no worries, nothing to see.
 
Old 24th Jul 2011, 02:13
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I have tried really hard to make sense of Bearfoil's posts as I figured someone so prolific a poster must have something important to say. All I see are lots of words used to say nothing. It is like listening to a politician answering a question.

Do I need a decoder ring and is it worth the price of a cereal box to get one?
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Old 24th Jul 2011, 04:13
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Techman,

LOL, I'm inclined to agree, I was slightly baffled by that last post as well.

'Smile and nod' might be an appropriate answer.
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