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AF447 final crew conversation - Thread No. 2

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AF447 final crew conversation - Thread No. 2

Old 19th Mar 2012, 10:13
  #201 (permalink)  
 
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RTLU

@MM43:

THx, edited the link.

@ CONF iture:

Maybe I was not clear, this did not occur to AF447!.

It was a reply on your suggestion of extending the slats.

Extending the slats could be an attempt to regain control
When TLU is deactivated (TLU NOT AVAIL) in flight a safety feature is to allow full rudder deflection when needed - at landing -.
Selecting S/F handle to CONFIG 1 will extend slats and if slat arrives @16 a backup circuit drives the TLUs to ALLOW for full pedal(35) and rudder deflection (35) if required.

This would have been visible in the TLU trace.

Many data are missing ...
The BEA has provided too little.
IMO only relevant items have been and will be published.
Nevertheless some questions indeed have to be answered or explained.

Last edited by A33Zab; 19th Mar 2012 at 11:27.
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Old 22nd Mar 2012, 22:12
  #202 (permalink)  
 
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Originally Posted by A33Zab
When the RTLU is at minimal (0 RVDT angle) the RTLU limits the rudder input to 4, to be accurate this is 3.7 (CMM).
Interpolating the low resolution TLU trace its value was ~4.2 (RVDT angle) just before @02:10:05.
4.2 + 3.7 ~ 7.9 at which it was freezed by PRIM at the start of the speed monitoring process.
Before I adventure further in that exchange, what do mean exactly by 'RVDT angle' ?
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Old 23rd Mar 2012, 00:45
  #203 (permalink)  
 
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'RVDT angle' ?

I don't know s*** from Shinola, but that's never stopped me before.

Isn't that an angle sensor?
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Old 23rd Mar 2012, 01:08
  #204 (permalink)  
 
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Technology of hydraulic cylinder position feedback.

Isn't that an angle sensor?
Not quite, or at least not directly. Probably Rudder VDT.
Now what is a VDT? See this link for a clue Modern LVDTs in New Applications in the Air, Ground, and Sea | Sensors
We'll let A33Zab grade this exercise. (And the winner is Lyman, it seems!)

Last edited by Machinbird; 23rd Mar 2012 at 01:25. Reason: acknowledging a winning answer.
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Old 23rd Mar 2012, 01:11
  #205 (permalink)  
 
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Rotary Variable Differential Transformer?


Edit, slow down lyman. Displays my sailboat's Rudder deflection.
.
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Old 23rd Mar 2012, 01:19
  #206 (permalink)  
 
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@CONF iture:

Before I adventure further in that exchange, what do mean exactly by 'RVDT
angle' ?
Maybe this clears up.

LVDTs
The linear variable differential transformer (LVDT) is a sensor used to measure displacement in the industrial environment. An LVDT consists of three coils of wire wound on a hollow form. A core of permeable material can slide freely through the center of the form. The inner coil is the primary coil, which is excited by an AC source as shown. Flux formed by the primary is linked to the two secondary coils, inducing an AC voltage in each coil. When the core is centrally located in the assembly, the voltage induced in each primary is equal. If the core moves to one side or the other, a larger AC voltage is induced in one coil and a smaller AC voltage in the other because of changes in the flux linkage associated with the core.

RVDTs
The rotational variable differential transformer (RVDT) is used to measure rotational angles and operates under the same principles as the LVDT sensor. The LVDT uses a cylindrical iron core, while the RVDT uses a rotary ferromagnetic core.


Item 6 in drawing below are the 4 RVDTs.

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Old 23rd Mar 2012, 01:45
  #207 (permalink)  
 
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Talking "Rotary Variable Differential Transformer?"

Yeah, Lyman, I Googled it too, but I knew they'd know I Googled it, so I didn't post it. (see emoticon)

I did learn that a transducer can be used instead of a variable transformer, with the same effect.
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Old 26th Mar 2012, 00:51
  #208 (permalink)  
 
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Originally Posted by A33Zab
When the RTLU is at minimal (0 RVDT angle) the RTLU limits the rudder input to 4, to be accurate this is 3.7 (CMM).
Interpolating the low resolution TLU trace its value was ~4.2 (RVDT angle) just before @02:10:05.
4.2 + 3.7 ~ 7.9 at which it was freezed by PRIM at the start of the speed monitoring process
Maybe I could dispute or argue on those numbers but to be honest I don't have the knowledge and documentation to go much further in that direction.
And overall I like what you said here :
This would have been visible in the TLU trace
Nevertheless I'd like to see the trace for the S/F lever position, especially when selecting FLAP 1 is at some point part of the STALL RECOVERY procedure.

IMO only relevant items have been and will be published
The AP/FD vertical mode trace is a relevant item for the reason I have already mentioned here but is nowhere to be seen ...


I do feel for the families of the 3 pilots who are put under such a negative light in such a dishonest and oriented program :



The families need all the data - Those data do not belong more to Airbus and the BEA that they belong to them.

Last edited by CONF iture; 26th Mar 2012 at 12:16. Reason: link
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Old 30th Mar 2012, 22:10
  #209 (permalink)  
 
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Lots of ideas from lots of folks. Unfortunately we have no way of knowing their professional backgrounds. Some engineers, some mechanics, some pilots and some ?????
I have said before and I'll say again this crash could not have happened if the aircraft had been diverted around the CBs as others did.
As pilots, we have all been told about the "ERROR CHAIN" in CRM classes. If you bother to look carefully at this accident, you will find many links in the error chain. If someone had broken any one of those links, the flight would have had a happy ending. I can list the links if required.
Pitot heat : Any system can be overloaded past it's limit. My knowledge of these systems on the ones I flew was "low" heat on the ground and "high" heat in the air. These systems are not able to cope with supercooled water of the magnitude encountered by this flight, hence the loss of many systems which are dependent on proper pitot function.
It's been over a year of chatter on how the crew should have recovered from the subsequent stall while in turbulence with many warnings flashing, ringing and blowing and it doesn't seem as if it will end soon. My view however is as stated above. Stay away from CBs at any altitude but more so at high altitude and arrive alive.
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Old 31st Mar 2012, 00:30
  #210 (permalink)  
 
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Originally Posted by thermostat
Stay away from CBs at any altitude but more so at high altitude and arrive alive.
It has been a few years since I roamed the high altitudes with frequently unreliable radars in my military jet, and your statement is very true, but sometimes difficult to fully implement.

Solitary cells are easy to circumnavigate. When they shoulder together in lines and large areas it becomes more problematic. The upper ice crystal portions of Cb clouds are weak radar targets. Although radars can be very helpful, they can also degrade or be mismanaged. When that happens, as it seems may have happened in the AF447 case, it is almost inevitable that you may get closer to a cell or cells than you wished. From the turbulence encountered-judging from the BEA report-they did not fly into the core of a cell, but instead into a peripheral area. But it was close enough to cause a problem.

Sometimes you do not succeed in breaking the first link in the accident chain. For this reason, you should break as many other links in the chain as possible. That is the source of the chatter you remarked upon.

We cannot absolutely avoid some proximity to Cb cells. To attempt to do so would shut down large portions of the world's air commerce. It isn't going to happen.
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Old 31st Mar 2012, 00:41
  #211 (permalink)  
 
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Originally Posted by CONF iture View Post
in such a dishonest and oriented program ...
Dishonest how, and can you prove it?

The families need all the data - Those data do not belong more to Airbus and the BEA that they belong to them.
What would the families do with it? Who would they take it to? The whole point of investigative agencies that are set up to be independent from regulators and the airlines (of which the BEA is one) is that they have nothing to lose or gain in the outcome. The families could take the data and pay someone to read it, but the conclusions derived from that would be worthless on the basis that the families' lawyers would have paid them to try to exonerate the crew, just as the same allegations could be levelled at DGAC, Airbus or AF if they had a hand in the investigative process itself.
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Old 31st Mar 2012, 02:10
  #212 (permalink)  
 
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Cool

Hi,

What would the families do with it? Who would they take it to? The whole point of investigative agencies that are set up to be independent from regulators and the airlines (of which the BEA is one) is that they have nothing to lose or gain in the outcome. The families could take the data and pay someone to read it, but the conclusions derived from that would be worthless on the basis that the families' lawyers would have paid them to try to exonerate the crew, just as the same allegations could be levelled at DGAC, Airbus or AF if they had a hand in the investigative process itself.
What would the families do with it?
That's not the good question
Again it's just to try to understand the lawyers position on this problem
It's a law problem .. no more
Airbus is a party cited in the trial has come .. as well as family associations
It should therefore be treated equal .. which is not the case .. since Airbus has access to parts (FDR furnished to them by BEA) that will eventually be used at trial .. while the associations of families do not have access to because that the judge in charge of this case want not joint those pieces to the trial record .. (so far)
Unfair ...simple as that ......
the same allegations could be levelled at DGAC, Airbus or AF if they had a hand in the investigative process itself.
Airbus have not a hand in the investigative process .. fair enough .. but be sure they analyze each stances from the listing of FDR and they can use their results in court if necessary
Family associations do not currently have this opportunity

Last edited by jcjeant; 31st Mar 2012 at 02:32.
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Old 31st Mar 2012, 02:23
  #213 (permalink)  
 
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But Airbus has not been granted access to the FDR in order to prepare a legal case, has it? It's simply because, as the manufacturer of the airframe, they need to ascertain whether or not there is a defect in the design that could cause more accidents. Are you seriously suggesting that such data be withheld until the trial is complete?

Even with the data that has been released, there are those on here that continue to insist that the zoom climb to stall was uncommanded despite the FDR data proving the exact opposite. Even if the raw data was released to the families, they couldn't do much with it. They could try sending it to the NTSB or AAIB who would in all likelihood tell them exactly the same things that the BEA are saying. The trial wont begin until the full report is released in any case, at which point all the relevant data will be in the public domain.
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Old 31st Mar 2012, 02:34
  #214 (permalink)  
 
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Cool

Hi,

But Airbus has not been granted access to the FDR in order to prepare a legal case, has it?
Are you naive ?
And again it's not the good question ...
It's regard of laws
The fact is they are cited party in the trial as the families association and must be considered equal..
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Old 31st Mar 2012, 02:38
  #215 (permalink)  
 
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............. until the full report is released in any case, at which point all the relevant data will be in the public domain...
agree

but I doubt that many posters on this forum will agree on what's relevant, especially if it doesn't match their theory
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Old 31st Mar 2012, 02:40
  #216 (permalink)  
 
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Cool

Hi,

agree

but I doubt that many posters on this forum will agree on what's relevant, especially if it doesn't match their theory
Again ....
Nothing to do with theory or shadow agenda .. it's a law problem
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Old 31st Mar 2012, 17:52
  #217 (permalink)  
 
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jcjeant,

I think you are getting the cart placed in front of the horse. It is not a "law problem," so far. Determination of the causes or probable causes have not been determined as of yet. The BEA has the responsibility to investigate the accident, assemble all of the available data and evidence, consult with any entity that may provide greater insight into the potential meanings of the evidence and data including providing of specific information to enable testing and confirmation of potential findings, followed by assembling a final report based on the pertinent data and supporting findings as to causes, probable causes and undetermined causes. At the conclusion of the BEA's investigation the final report is issued and presented to the responsible French Court. At the time this transfer occurs, it then become a "law problem" to be resolved. Prior to this report, no party of interest that cannot contribute to in depth understanding, i.e., technical expertise or human behavior as it pertains explicitly to the accident should have access to the full actual data.

The BEA can (as does the NTSB in the US) choose to release certain preliminary information to the general public it has found to be pertinent and indicate what other tasks are being performed in its investigation as it proceeds towards conclusion. The BEA has chosen to do this through interim reports. The BEA may also decide to privately apprise the families of the victims, out of courtesy, of their investigation methodology, status, etc., perhaps more in detail than what may be released to the general public. It is the BEA's call, but nothing is owed in advance of the final report being written and turned over the French Court.

I am not aware of any highly technical aircraft accident investigation where the investigative body could not consult with the airline operator, aircraft, engine or avionics manufacturers to gain additional knowledge of the system or systems, while sharing available need to know data to hopefully enable correct conclusions to be drawn. It doesn't mean the lawyers to be involved in the future litigation are entitled to this exchange of information at the actual time the exchange occurs.

Dozy is correct in his assessment! Welcome back Dozy

TD

Last edited by Turbine D; 31st Mar 2012 at 17:54. Reason: wording correction
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Old 31st Mar 2012, 19:16
  #218 (permalink)  
 
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Cool

Hi,

I am not aware of any highly technical aircraft accident investigation where the investigative body could not consult with the airline operator, aircraft, engine or avionics manufacturers to gain additional knowledge of the system or systems, while sharing available need to know data to hopefully enable correct conclusions to be drawn. It doesn't mean the lawyers to be involved in the future litigation are entitled to this exchange of information at the actual time the exchange occurs.
It's unfortunate you are not aware of the french laws ...
Airbus have entire FDR listing
Families associations have not FDR listings
A complaint against Airbus (recognized as valid) was filed by associations of families
Airbus and families associations are two parties involved in the legal process
Both parties must be treated equally
It's nothing to do with investigation .. or technical recommendations ....
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Old 31st Mar 2012, 19:48
  #219 (permalink)  
 
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Originally posted by jcjeant
It's unfortunate you are not aware of the french laws ...
Care to enlighten me? Has there been parallel legal investigatory actions on going by the French magistrates while the BEA is doing the technical investigation? The judiciary has priority to investigate any object from the accident site that might be used as evidence which may delay and prevent the safety investigators from carrying out their investigation. Has this happened? Standard 5.12 of Annex 13 explicitly states that the records derived from these devices should not be made available for purposes other than safety investigation unless an appropriate authority has determined that the proper administration of justice outweighs the adverse impact on aviation safety. Have the French magistrates ruled otherwise at this point?
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Old 31st Mar 2012, 19:55
  #220 (permalink)  
 
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Cool

Hi,

Has there been parallel legal investigatory actions on going by the French magistrates while the BEA is doing the technical investigation?
Yes ..
The "juge d'instruction" asked to "experts" called by him (in a pool of experts who are stdby for such investigations) to make their own investigations ..
It's the judicial process ... like in any accident (cars .. buses .. trains)
These experts will present their results at the trial
The BEA will also (certainly called by the judge) present their results
Note that the parties involved can have also their own experts and they will also present their results on the trial
These can be contradictory and it is the judge to decide (it can also call other experts for cons expertise)

Last edited by jcjeant; 31st Mar 2012 at 20:08.
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