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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 4th May 2011, 07:28
  #641 (permalink)  
 
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Recorder Locations (distributed memories)

There is obviously some merit to rethinking the CVR/FDR data recorder concept. One proof point is (if I understand correctly) that BEA is indeed searching also for the other memory units in the aircraft, i.e. within the flight deck and engine FADEC systems, even though they are not hardened to the extent of the CVR/FDR memory units.

However, a simplistic relocation / multiplication of units brings its own problems.

- The added dead weight and space requirement of each unit and its power feed. As noted before, it performs a critical function at most only a few times in the lifespan of the aircraft.

- Each unit needs a reliable incoming data feed with all recorded parameters. For obvious reasons it would be impractical to feed each recorder with primary data (i.e. individual electrical/pitot/etc. sensor lines). This implies a bus structure and furthermore a need for multiple data buses, otherwise the "single point of failure" of the recording system just shifts from the CVR/FDR to the bus multiplexer equipment. Multiple buses and multiplexers add more weight.

- Increased amount of wiring. The data buses could probably be light optical fibers, but even so I presume there is usually not much extra wiring space in an aircraft. So the installation probably needs to be considered at the basic design phase. This means the time to deployment is long.

- An option might be to have wireless transmission of the data to the recorders, but that brings with it some radio spectrum management issues. To exaggerate a little, you probably don't want the recorders to be susceptible to your seat neighbour's computer Wi-Fi. (I remember Gulfstream has done some trials of using wireless links - IIRC for spoiler actuators - but this is not a trivial issue).

- Looking at recent crashes and the CVR/FDR searches, in my mind the eventual success rate of finding the CVR/FDR in a usable state and extracting the data has been remarkably high. The main problem has been to find the actual aircraft wreck - once it is found the recorders have also eventually been found fairly quickly, actually in each recent case that comes to my mind.

- From the above it follows that a wiser way of spending R&D and development money, with a higher benefit, could be to improve pinger and CVR/FDR locating techniques, rather than to just add recording equipment to the airplanes.

Just my 2 cents.

Last edited by snowfalcon2; 4th May 2011 at 08:08. Reason: Clarification
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Old 4th May 2011, 08:25
  #642 (permalink)  
 
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Airbus A330-203, manufacturer serial number 660, registered as F-GZCP.
First flew on 25 February 2005.

The U.S. NTSB and TSB of Canada issued safety recommendations on March 9, 1999, to require:

By January 1, 2003, all newly manufactured airplanes required to carry both a CVR and FDR be fitted with two combined voice and data recorders, one recorder located as close to the cockpit as practical and the other as far aft as practical.
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Old 4th May 2011, 08:55
  #643 (permalink)  
 
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@ DJ77 post #582:
Thank you Sir, much appreciated
Seems a good idea to drop & search for another ULB, while they're at it as you said.

@ Bizman posts #572 & #621:
1/ Seen from here, english is (still) the first link on each item since the Apr 29th briefing on the english page. French is first link on every item on the french page.
2/ What's the point ?

@ DozyWannabe post #624 :
Just quibbling, perhaps, but the Habsheim crash killed 3.
/end of off-topic and for your post.

@ MJC2 post #628 :
+1 !
& thanks for the digging work
I assume the original mis-interpretation (also) came for the bad translation of interim report #1 form french to english (at last on this sentence, but there are more examples of "clearly french to english bias" in the report).

@ all, about the recorders reseach, location on the aicraft, technology and so on : you may find it's worth (if not already done) to read the Report from the International Working Group on Flight Data Recovery, 22 December 2009 published by the BEA on its website.
Direct links : French version / English version.
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Old 4th May 2011, 13:07
  #644 (permalink)  
 
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No power, no data

Caygill,

The solution must be based in:

"Fault tolerance and graceful degradation".

In this case the idea would be allow a "minimum of information" to allow investigators understand the facts until the sea surface impact.

How it would be designed? We need to prepare an Specification on "what we need".

Obviously in an extreme "electrical power loss" in the a/c systems you may ask: Why record?

Unless you distribute also some sensors.

There is an option for the SSFDR, the accelerometer. That could work integrated to distributed sensors, and that could be made "power independent" of aircraft power during some few minutes.

This is a "System Issue" and IMO there is room for improvement.

What in my opinion is not acceptable is:

Spend years to start (to try) understand what led to this loss.
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Old 4th May 2011, 13:21
  #645 (permalink)  
 
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RRNDB, do your design aircraft? I hope not or I am sure that commercial aircraft accidents will happen weekly. Maybe you should start a new thread for flight recorders. Graybeard has answered your recommendations adequately, so let's move back to this thread, and the reason for it.
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Old 4th May 2011, 13:22
  #646 (permalink)  
 
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Something should be done

snowfalcon2,

could be to improve pinger and CVR/FDR locating techniques
I agree. A good start point!
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Old 4th May 2011, 13:27
  #647 (permalink)  
 
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How many hull-loss accidents have NOT been solved as a result of unusable/unrecoverable flight recorders? It can't be more than 5. So hand-wringing about sensors is pretty much pointless if the actual goal is flight safety. The introduction of CVRs and FDRs has increased airline safety by an order of magnitude - only another order of magnitude improvement would justify changing the whole system. I think good training with emphasis on flying skills is much more important than obsessing over recorders and sensors. I get the strong feeling that the bad man of AF447 is the flight management system and the over-reliance on automation to fly the airplane.
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Old 4th May 2011, 13:32
  #648 (permalink)  
 
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RR NDB ref your Tail Fin separation (before or at sea surface crash?) post ... #593

RR NDB:

There has been much interesting discussion on these pages about whether a large airliner can be kept flying in a controlled manner minus a VS.

Shown below is a 1961 picture of an RAF 74(F) Sqn English Electric Lightning Mk1. It has a 60 degree swept wing and a low set slab tailplane.

It landed uneventfully with a considerable amount of VS (vertical stab / fin) missing.
The structural failure was caused by inter-acting shockwaves from adjacent aircraft.

The pilot, Flt Lt Jim Burns, was the outside man in a 'finger four' low level air display high speed formation pass. As the formation of 4 aircraft crossed RAF Coltishall airfield at Mach 0.95/620 knots IAS and 200' altitude the outside aircraft pulled up abruptly and then made a leisurely circuit. It landed minus about 75% of it's vertical tail in an otherwise normal configuration of full flap and a Vref of 165 knots. The pilot was unaware of the VS loss until he got out of his cockpit: his VHF radio antenna was at the top of the fin and had also departed

so no radio, and yes it was VHF when this happened 5o years ago.


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Old 4th May 2011, 13:36
  #649 (permalink)  
 
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Originally Posted by Caygill
And what would the recorders record after a complete electrical failure?
I think that is the point RR_NDB wants to bring forward :
If the recorders have their own independent power supply, they will keep recording.

This has already made the object of a recommendation following the Azores glider as the last 20 minutes of data are inexistent :
ICAO, all civil aviation authorities and safety investigation authorities:
Take into account the circumstances of this particular occurrence in their deliberations on the requirements for independent power supplies for on-board aircraft recordings.
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Old 4th May 2011, 14:34
  #650 (permalink)  
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rubberband2

That is a great pic.... It supports directional stability w/o Rudder, but it appears that the Fin is mostly present. The Rudder and the Vertical Stabilizer are responsible for two different aspects of flight.

The Rudder is basically a trimming device, the VS provides directional stability. It can be said, therefore, that the Rudder's task is the opposite of the VS, it stabilizes Yaw, in the turn, or establishes a crab for offset.

An a/c can fly quite well without the Rudder, as your pic shows. An a/c is not airworthy w/o the Fin.
 
Old 4th May 2011, 14:47
  #651 (permalink)  
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CONF iture;
I think that is the point RR_NDB wants to bring forward :
If the recorders have their own independent power supply, they will keep recording.
If that is RR_NDB's point, then he hasn't thought it through very well. He hasn't said what parameters the recorders will keep on recording and how that works.

The only suggestion of independent power supply that has emerged was after SR111 and that was the voice recorder.

Last edited by PJ2; 4th May 2011 at 14:58.
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Old 4th May 2011, 14:59
  #652 (permalink)  
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PJ2

Loads?? Direction of Flight?? GPS (altitude and trajectory) ?? Wouldn't that be most important in the post mortem, the sequence of loads on a passive a/c??
 
Old 4th May 2011, 15:13
  #653 (permalink)  
 
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He hasn't said what parameters the recorders will keep on recording and how that works.
Obviously, current boxes wouldn't record a thing, but you could add some gyros to them to get them record accelerations... Some aircraft used to have a separate simple pitot-static system in the bum for their rudder travel limiters... could easily be done to feed an FDR. ...But why?

If the ship is completely dead, electrically, what a self-powered FDR might record (on a FBW aircraft!) beyond that point is totally predictable anyway, isn't it?

(BTW... "West of the Moon" I get, since the Moon always shows us the same side... But "East of the sun"? Yer 'aving us on! )
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Old 4th May 2011, 15:35
  #654 (permalink)  
 
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Cool

Hi,

Concretions on the CVR pinger ..... indication of a crack ?



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Old 4th May 2011, 15:51
  #655 (permalink)  
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Were Load traces supplied in the report Perpignan??
 
Old 4th May 2011, 16:04
  #656 (permalink)  
 
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Concretions on the CVR pinger ..... indication of a crack ?
I see what looks to be corrosion oozing from those black keeper brackets, but the image isn't quite clear enough to be sure of much...
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Old 4th May 2011, 16:05
  #657 (permalink)  
 
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Brief note re the discussion about a/c continuing to fly with part of the vertical tail missing....

As an aeronautical engineer, I wondered a few times, why todays airliners with two wing-mounted engines have such huge vertical tails, compared to other aircraft.
The answer turned out to be, that the 'design case' is directional stability and control during an engine failure at low speed (i.e., during take-off or landing).
In most other 'design cases' a much smaller vertical tail would be adequate, as demonstrated by that B-52...

Even without a vertical tail, the rear end of the fuselage provides some "weathervane" stability, but in that case the complete lack of a rudder can be a nuisance.....
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Old 4th May 2011, 16:08
  #658 (permalink)  
 
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Originally Posted by bearfoil View Post
Were Load traces supplied in the report Perpignan??
bear, the report is on the BEA site.
It's some time since I last read it, so, I'm sorry, you'll have to do your own research.
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Old 4th May 2011, 16:23
  #659 (permalink)  
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Of less importance than OEO performance is the fact that some twins are "short coupled", meaning the tail's "Arm" has less effect than an a/c with a longer fuse twixt flap and tail cone. The 777 looks much "better" (balanced) than the guppy, for this reason, imo.

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Old 4th May 2011, 16:52
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Quote:
Originally Posted by Caygill
And what would the recorders record after a complete electrical failure?

I think that is the point RR_NDB wants to bring forward :
If the recorders have their own independent power supply, they will keep recording.
My point of logic was: if you have no power for instruments and sensors there is absolutely nothing to record.

Sure, you can verify that any specific data was missing, but if the data cannot be generated or transferred, it cannot be recorded. If you loose all power on a modern aircraft there is nothing left to record if you do not create a completely independent array of sensors powered equally independently
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