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The BBC article is suggesting that the flaps did not retract in sync .. that "they are not moving together" ... although quite how they got to that conclusion from the CVR is not clear ...
As normal practice is to retract in stages, I would have thought the imbalance would have become obvious before it became fatal, by the time you have a bootfull of rudder and the stick hard over, you would not be calling for another stage of flap retraction, you'd be thinking "hmm, that does not seem to have gone well" ... |
Sounds a bit like flap retraction instead of gear retraction, with predictable consequences.
There was a Io-co in the UK that had the same problem. The standard accelleration call was "FLAPS UP SPEED". A procedure that was utterly crasy, and I told them so. Well, after two aircraft staggered away with a lack of flaps at very low speed, the accelleration call was finally changed. Basic rule of aviation .... if it can happen, it will happen. And you can bet your bottom dollar it will happen on the fourth flight at 03:00, when everyone is dogtired and half asleep. So try and make your procedures as buIIet-proof as possible. Unfortunately, some of these new-entrant airlines were run by beginners, who were always reinventing a very old wheel. |
Asymmetric flap?
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From russian "pprune" (forumavia.ru):
If the takeoff to be completed with flaps28 - they should be retracted with 2 steps: speed 300 km/h - set flaps15, after acceleration to 330 km/h - set flaps up. According info leaks somebody in the cockpit told : "speed 300.... f*ck, flaps!!! " That's why there is a version that one of pilots selected flaps from 28 to 0 inadvertently. |
Karel_X
CVR transcript can be authentic, but a time stamping is missing. Flaps problem may arise some 1-2 min later after gears up. |
The BBC report looks credible and clearly refers to the FDR readout (NOT CVR), and clearly mentions "flaps not movng together". Sounds like flaps assymetry induced LOC.
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Surely flap asymmetry would simply cause a flap lock-out?
It certainly sounds like a configuration error caused the accident, whether as the result of system failure or aircrew mis-selection. How are the slats and flaps 'automatically' interconnected? Are the slats still extended when the flaps move from 28° when 15° flap is selected? |
Flap asymmetry can be a very big problem.
Recall the UA DC-10 at Chicago when significant items were damaged when the engine came off the pylon. And then there's the one I had in a Viper long ago. http://i120.photobucket.com/albums/o.../rightwing.jpg In my case, the FBW flight controls helped me a lot! The assymetry brake sensor was outboard, and my failure was with the connection to the flap drive motor in the fuselage. The "brake" couldn't work because the flap was not connected to any control mechanism. Duh. My understanding of the flap control surfaces on this plane is that they are independent from side-to-side. So as with my "problem", one side could fail and the other worked per normal. At slow speed and with assymetrical flaps you could have a serious inpact on total lift for the plane and also have roll problems due to more lift on one wing than the other. My problem happened after I was above the minimum control speed so I mainly had a lot of drag and used all but 1 pound of stick authority to keep control( according to data recorder we had on early Vipers). Unless those guys pushed forward right away and reduced AoA/pitch to gain speed, they were doomed. |
I don't think it will take them long to confirm if it was either assymetric slat/flap or a configuration stall. I don't buy the smooth sea, dark night, high acceleration somatogravic illusion.
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The BBC report looks credible and clearly refers to the FDR readout (NOT CVR) |
As far as I can filter info from noise, it was stall, caused by takeoff misconfiguration, but what was a source of it still unclear.
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Kulverstukas, do you know if this FDR's medium is digital (chips), optical or tape?
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Quote: The BBC report looks credible |
The question is who or what is the BBC's source? From previous experiences with accident reporting by the BBC I would wait for an official announcement by the authorities!
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Tape
http://www.reaa.ru/yabbfilesA/Attachments/IMG_6289.jpg CVR MARS-BM 70A-11 left, FDR MLP-14-5 right |
BBC headline:
The main flight recorder from the Russian jet that crashed into the Black Sea on Sunday has revealed that faulty flaps were to blame, Russian media say. |
Kulverstukas, many thanks!
One more item if I may - do we know what parameters and sample rates there are with this kind of an installation? I'm not expecting thousands of parameters as may be available on modern transports, but I'm wondering if it is more than we might see on B737-200/300/400 types, for example, (~80 to 250 parameters depending on data frame and legal requirements). |
http://lms.aeroflot.ru/data/tu_154_systems/tm14.pdf
48 analog channels and 32 single events channels. 3 analog channels are 8Hz, rest are 2Hz. |
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