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Old 28th Dec 2016, 18:36   #181 (permalink)
 
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Thanks, Kulverstukas.

I see the flaps are fully retracted on that wing, which cannot happen post the accident (presuming screw-jacks, like all other aircraft). So it is looking like early an inadvertent flap retract could be the problem.

Last edited by silverstrata; 28th Dec 2016 at 20:50.
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Old 28th Dec 2016, 18:38   #182 (permalink)
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, again, many thanks!

silverstrata, I noticed too, that they were retracted but that in itself is not, for the moment, evidence of anything other than "retracted flaps".

Collaborating evidence would be time-stamped slat/flap position, (both left & right, which may not be available parameters), airspeed, pitch, AoA & correlated CVR recording.
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Old 28th Dec 2016, 18:40   #183 (permalink)
 
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Quote:
I see the flaps are fully retracted on that wing, which cannot happen post the accident (presuming screw-jacks, like all other aircraft).
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Old 28th Dec 2016, 19:09   #184 (permalink)
 
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Kulverstukas do you have any information on the leading edge slats, such as flight deck location in relation to gear, flap and minimum speed for retraction. Any cockpit warnings/alerts for t/o without deployment. Are they linked to flap settings.
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Old 28th Dec 2016, 19:16   #185 (permalink)
 
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Any cockpit warnings/alerts for t/o without deployment.
NOT T/O READY warning light and sound.

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Old 28th Dec 2016, 19:23   #186 (permalink)
 
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According to foreign news sources (interfax),combination of technical malfunction with pilot error led to inadequate lift to maintain flight is reported as the cause.
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Old 28th Dec 2016, 20:43   #187 (permalink)
 
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Quote:
Originally Posted by PJ2 View Post

silverstrata, I noticed (that flaps) were retracted but that in itself is not evidence of anything other than "retracted flaps".
Not quite. On the CVR we have a "speed" call, and then a surprised exclamation about "flaps". I would say that is prima face evidence that there was something unusual or unexpected about the flaps. One possible unexpected flap condition is the flaps being retracted early, with insufficient speed. Another could be asymmetry, but most aircraft will lock automatically before an asymmetry develops.

Unexpected early flap retraction is the front runner, in my opinion. And it happens. As I relate above, there was a UK Io-co who had an acceleration call of "flaps up speed", which predictably resulted in a couple of inadvertent early flap retracts.

Thanks for the screw-jack image, Kulverstukas - that is an impressive array of hanging ironmongery. A most informative collection of pictures.

Last edited by silverstrata; 28th Dec 2016 at 20:56.
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Old 28th Dec 2016, 21:17   #188 (permalink)
 
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in my opinion the accidental flap instead of gear retraction alone does not explain it.

on the one hand it should be, even when it is of course bad airmanship and a dangerous situation , finally manageable by an experienced crew since the flaps and slats retract slowly while the reduced drag lets the plane acclerate quickly to its minimum clean speed. keep the nose slightly below stall angle, let the speed build up and then start to climb away. there were no obstacles ahead because they immediately were above the sea so no need to build up altitude at this moment .

on the other hand - even when not manageable - the "gear up" command comes shortly after liftoff and when the pilot instead of the gear lever operated the flap lever to "0" flaps resulting in a stall and crash it would have occoured in very close vivinity of the runway. i do not see a scenario where the plane struggels several miles out to the sea and even makes an u turn due to early flap retraction.
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Old 28th Dec 2016, 21:22   #189 (permalink)
 
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Excactly my experience and thoughts as well.
There has to be more or this accident would be off the end of the runway.
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Old 28th Dec 2016, 22:06   #190 (permalink)
 
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Old 28th Dec 2016, 22:30   #191 (permalink)
 
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Even if the mods like to pull my comments. The two main gear pictures indicate that the main gear was retracted, especial the bent oleo on the first picture. It got a lot of load on impact, but asymmetrical as the oleos are not bent the same. The impact speed was quite high and the damaged oleos show that the impact was not flat but at a relative high angle of attack.
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Old 28th Dec 2016, 23:07   #192 (permalink)
 
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FDR or CVR recovered first?

I have a question.

Initially, it was reported that the FDR was recovered.

Then there were reports purporting to be flight deck conversations.

Only after the first of these appeared was it announced that a second recorder was even located.

Were the initial reports mistaken, and it was actually the CVR that was recovered first, or are all the flight deck transcripts actually fake news amplified by the internet echo chamber?
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Old 28th Dec 2016, 23:21   #193 (permalink)
 
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On the picture that Kulverstukas posted, there is a righthand maingear. It is interesting that first pair of wheels are torn off. Quite a force. Normally first pair of wheels hit the ground first, as gear is angled and they are lowest. Could these missing wheels indicate, that gear was not retracted, when plane hit water? First pair of wheels hit water, probably a wave, which at that speed is as hard as a concrete wall.
But then again, hydrocylinder is extended and bent, which means that gear was retracted during impact.
Here is a short video about how Tu-154 gear works:
https://www.youtube.com/watch?v=HhupJGUZYLQ

Last edited by Prada; 28th Dec 2016 at 23:56.
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Old 29th Dec 2016, 06:55   #194 (permalink)
 
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Quote:
Originally Posted by 5 APUs captain View Post
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.
That's incorrect data. According Tu154 SOP in case of T/O with flaps 28:
- configuration change 28-15 - at speed 330-340 km/h
- from 15 to clean wing - at not less than 350 km/h
- 380-400 km/h (depending on weight) must be provided at the end of transition
So if they had 300 with clean wing.....
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Old 29th Dec 2016, 07:11   #195 (permalink)
 
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Are these data recalculated from Knots, or is the manual and SOP for Europe in SI units ?
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Old 29th Dec 2016, 08:31   #196 (permalink)
 
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It's actual data from SOP without any cut. I think it's hardly to find TU154B SOP in other language version than Russian
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Old 29th Dec 2016, 08:32   #197 (permalink)
 
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All USSR technical data is in metric units.
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Old 29th Dec 2016, 10:40   #198 (permalink)


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Looking into this one
Sergey Bainetov, the Russian Air Force's deputy head of flight safety
Minister of Transport, Maxim Sokolov

Latest press conference reports
https://sputniknews.com/trend/tu_154...cue_operation/

Also - sorry, but all talk of flaps may be premature - a single 'leak' and 'assumptions' in an echo chamber vacuum?
Quote:
The Russian news network Life.ru quoted a source close to the investigation as saying that the final words uttered by the Tu-154's pilot indicated a possible flap fault.
www.Life.ru referred to the final recording of the cockpit before the crash, in which the pilot can allegedly be heard yelling "the flaps, damn it!" which was followed by "commander, we're going down." This has yet to be officially confirmed. Life.ru also quoted Russian aviation expert Viktor Zabolotsky as saying that flaps-related problems typically lead to a situation where pilots finally prove to be unable to take control of a plane while in the air.
He was echoed by another Russian aviation expert, Oleg Smirnov who told the online newspaper Vzglyad that his first assumptions regarding the Tu-154 crash were also related to a flap failure. The matter is that the plane disappeared just at the point during the flight when the wing flaps should have been retracted, according to Smirnov.
https://sputniknews.com/russia/20161...e-crash-cause/
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Old 29th Dec 2016, 10:42   #199 (permalink)
 
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The following is all speculation.

If they had a slat and/or flap misconfiguration that resulted in a too high AOA they could wind up in a deep stall, those T-tails are prone to. It is mostly unrecoverable even at high altitudes.

http://www.aviationtoday.com/regions/ca/3011.html

Lots of folklore about T-tail deep stall to find on the web. The FDR data should give an answer about that armchair hypothesis soon.
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Old 29th Dec 2016, 11:21   #200 (permalink)
 
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Press-conference of Investigation Commitee

No explosion. Diversion or terrorism doesn't ruled out.

Time of flight ~ 70 sec, 10 sec of catastrophic situation.

Max height 250 m

Max speed 360-370 km/h

https://www.rt.com/news/372130-tu154...h-malfunction/

Last edited by Kulverstukas; 30th Dec 2016 at 05:15. Reason: Link to RT
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