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Thread: Aeroflot Superjet 100 fire and evacuation at UUEE

  1. #21
    Senior Member Evan's Avatar
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    Quote Originally Posted by Alex - Spot-This ! View Post
    Yes, main gear went through the wings and tanks after first hard contact, setting everything on fire.
    No, the breach occurs after the last impact, but before the last impact, it **appears** that the MLG is either detached or collapsed (or never extended), when there is still no fuel tank breach.

  2. #22
    Senior Member Evan's Avatar
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    Quote Originally Posted by Evan View Post
    No, the breach occurs after the last impact, but before the last impact, it appears that the MLG is either detached or collapsed (or never extended), when there is still no fuel tank breach.
    Maybe it's a trick of the low-res video, but have a closer look.

    https://www.youtube.com/watch?v=HG3_clcQIFI

  3. #23
    Administrator Alex - Spot-This !'s Avatar
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    Videos from inside the cabin show how main gear went through the wing and remained there for the entire landing

  4. #24
    Senior Member Evan's Avatar
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    Quote Originally Posted by Evan View Post
    No, the breach occurs after the last impact, but before the last impact, it **appears** that the MLG is either detached or collapsed (or never extended), when there is still no fuel tank breach.
    You know what... forget it. That video is too lowres to determine anything.

  5. #25
    Senior Member Evan's Avatar
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    Whatever the cause, a bounced landing like this shouldn't result in a breached fuel tank (or a broken wing spar). The DC-10/MD-11 had a problem with this (see Gabriel's previous post) and lessons were learned. Hopefully the investigation will focus on this.

    The wings:

    The SSJ wing has the second highest aspect ratio after the B787. Pains were taken to achieve this. The wing was optimized for cruise level flight.

    The gear:

    Quote Originally Posted by Alexey Dolotovski, Deputy Chief Designer (Aerodynamics) at SCAC
    We have a durable landing gear, excellent double-strut gear legs, a real work of art. They are able to endure the roughest landing without any damage. Of course double-strut landing gear is heavier than a single-strut one. But when a single-strut landing gear is mounted on the aircraft it turns out that the hinge fittings need to be reinforced. As it turned out the single-strut landing gear together with reinforced hinge fittings are heavier than double-strut landing gear. Our landing gear has lower weight as compared to the single-strut one installed on Embraer 190.

  6. #26
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Alex - Spot-This ! View Post
    Videos from inside the cabin show how main gear went through the wing and remained there for the entire landing
    Link please?

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  7. #27
    Senior Member Evan's Avatar
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    The MLG-to-wing setup:
    Click image for larger version. 

Name:	ssj-mlg.jpg 
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  8. #28
    Senior Member Gabriel's Avatar
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    We have a durable landing gear, excellent double-strut gear legs, a real work of art. They are able to endure the roughest landing without any damage.
    1- Depending on how you define "the roughest landing", this can actually be a bad thing. In the same way than super solid cars that would remain almost intact after a crash but with the occupants smashed inside.
    2- And it has just been proven wrong, unless this landing was rougher than the roughest one.

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  9. #29
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    1- Depending on how you define "the roughest landing", this can actually be a bad thing. In the same way than super solid cars that would remain almost intact after a crash but with the occupants smashed inside.
    2- And it has just been proven wrong, unless this landing was rougher than the roughest one.
    And it's not the first time the MLG has collapsed on landing.

  10. #30
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Well, it shouldn't. Fuse pins are there to prevent that hard landing loads transfer to the wing spar which then acts like a fuse itself. Like in the several DC-10 and MD-11 hard landing accidents where one of the wings pars failed, the airplane lost that wing, and the plane rolled inverted engulfed in flames. A fuse pin is NOT there to prevent the landing gear strut from going through the wing tanks, rather the opposite, sort of. The compression fuse pin is supposed to fail under high landing gear compression stress and let the strut go through the wing, except that there should be no fuel tank there because the landing gear assembly is located behind the rear spar which is the aft end of the fuel tank.

    I suppose that the British Airways 777 accident at Heathrow was a quite harder landing.
    25 ft/s (1500 ft/m)

    That accident, being at a high descent rate on soft surface, imposed very high loads both in compression and backwards. One landing gear failed under compression while the other failed under backwards force. One of the fuel tanks (don't remember which one) was protected as per design, the other one was breached because a secondary rod (that gives stability to the assembly) failed to fail as designed, and penetrated the fuel tank. Luckily the soft and wet ground helped avoid a fire.
    Actually, both MLG failed by design for upward compression (the outboard fuse pin failed on both of the main landing gear beams). I was wondering how a vertical compression fuse pin would work, expecting it at the trunnion, but it is actually at the gear beam (an airframe attachment structure) outboard attachment.

    The left wing tank was breached a bit between the upper wing skin and the rear spar. The center tank was breached when the right gear rotated inward and the drag brace tore off the rear spar web along with part of the center tank wall. The right gear then detached, striking and penetrating the aft fuselage, breaching the oxygen cylinder manifold (venting the oxygen, thank god there was no fire) and then went airborne, striking the horizontal stabilizer.

    The fuel pipes also fractured, spilling fuel until the spar valves closed.

    But that is all to be expected from a 777 falling out of the sky. Fuel tanks should be protected against the kind of rough landing we saw yesterday.

  11. #31
    Senior Member brianw999's Avatar
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    .....and yet again passengers get their hand baggage before evacuating. From what little I saw of the evacuation there seemed to be a distinct pause in front of each passenger seen with hand baggage. That equals a delay to other passengers evacuating and must surely have contributed to some of the deaths.
    Every passenger in possession of hand baggage should be prosecuted for manslaughter.
    If it 'ain't broken........ Don't try to mend it !


  12. #32
    Senior Member Evan's Avatar
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    Quote Originally Posted by brianw999 View Post
    Every passenger in possession of hand baggage should be prosecuted for manslaughter.
    And you don't think they could claim 'temporary insanity'? Have you seen that interior video?! Let he who has waded through the fiery aisles of Russian aviation with a clear head cast the first stone.

  13. #33
    Senior Member Gabriel's Avatar
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    On May 6th 2019 Roaviatsia (Russia's CAA) reported a static atmospheric discharge at about 2100 meters (6900 feet MSL) resulted in the failure of the radios and other equipment including the autopilot. The crew returned to Sheremetyevo squawking loss of radio contact, subsequently emergency. While landing on runway 24L the aircraft experienced a rough landing, bounces and partial destruction of the aircraft. Following the 4th touch down fire broke out at the tail section of the aircraft and the aircraft veered left off the runway coming to a stop between taxiways A2 and A3. The aircraft burned partially out, there were fatalities and injuries.
    http://avherald.com/h?article=4c797dd7&opt=0

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  14. #34
    Senior Member Evan's Avatar
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    Quote Originally Posted by BBC
    Pilot Denis Yevdokimov told Russian media that the lightning had interrupted communication with air traffic controllers and forced him to switch to emergency manual mode.
    Quote Originally Posted by BBC
    Russia's transport ministry has decided against grounding Superjet-100s, saying there is no obvious sign of a design fault.
    Hmmmmmmmmmmmmmmmmm. Ok, a grounding might be a bit hasty, but obvious signs of design faults...?

    Well, a lightning strike (not such an uncommon event) apparently knocked out the radios and the flight-control computers (if not the entire primary electrical system). That's not supposed to happen. There are rare forms of lightning that will exceed protections, but the odds of this are remote.

    And a hard landing resulted in breached fuel tanks. That's not supposed to happen either. So I think there is reason to say there are obvious signs of design faults here.

    Start with lightning protection. Are the composite conductive layers adequate? Is there any vulnerable area? What about transient protection and surge suppression of vital avionics? Is it adequate?

    Then I would want to know how a hard gear-collapse landing could result in a fuel tank breach. Does something need to be structurally rethought there?

  15. #35
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    Quote Originally Posted by Gabriel View Post
    Link please?
    My guess it is the second video here:

    https://www.liveleak.com/view?t=u6KG2_1557114046

  16. #36
    Senior Member Evan's Avatar
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    Quote Originally Posted by xspeedy View Post
    My guess it is the second video here:

    https://www.liveleak.com/view?t=u6KG2_1557114046
    I don't see any gear elements in these videos.

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    Quote Originally Posted by TeeVee View Post
    So much for the ultra modern up to date ssj..... hard landing and...
    Ultra modern? I don't think anyone ever said that. It was clear from the beginning the plane was a bit behind even compared to the E-Jets and the CRJs, let alone when compared to the E2 or the CSeries (I mean the A220). It is built by a company that doesn't have any experience in commercial airplanes, and it relies heavily on western components. To be honest, it seems Sukhoi has been struggling with its latest military jet as well.
    Then there is the sub-par dispatch reliability and the poor service and spare parts network.

    The SSJ is just an attempt by the Russians to get back into the game. It was never going to be a state of the art game changer.

  18. #38
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    Quote Originally Posted by Evan View Post
    I don't see any gear elements in these videos.
    There is some strut-like structure sticking out in the beginning of the first video.

  19. #39
    Senior Member Evan's Avatar
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    Quote Originally Posted by Black Ram View Post
    Ultra modern? I don't think anyone ever said that. It was clear from the beginning the plane was a bit behind even compared to the E-Jets and the CRJs, let alone when compared to the E2 or the CSeries (I mean the A220). It is built by a company that doesn't have any experience in commercial airplanes, and it relies heavily on western components. To be honest, it seems Sukhoi has been struggling with its latest military jet as well.
    Then there is the sub-par dispatch reliability and the poor service and spare parts network.

    The SSJ is just an attempt by the Russians to get back into the game. It was never going to be a state of the art game changer.
    Do a bit of research. There's a lot of high-tech development that went into the SSJ, particularly the 9.9 aspect ratio wings. The FBW is state-of-the-art and very robust, (using LLI (Liebherr Lindenberg) FCC's and Thales avionics, some purpose built from scratch). It is certified as a Protected Aircraft. It is also modern is its reduced complexity.

    "Ultra-modern", maybe not, but definitely a modern, 21st century aircraft. Much more modern than the 737-Max. There may be some serious design issues that come to light as a result of the investigation, but otherwise, it's a pretty impressive aircraft for a first-time effort.

  20. #40
    Senior Member TeeVee's Avatar
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    Quote Originally Posted by Black Ram View Post
    Ultra modern? I don't think anyone ever said that. It was clear from the beginning the plane was a bit behind even compared to the E-Jets and the CRJs, let alone when compared to the E2 or the CSeries (I mean the A220). It is built by a company that doesn't have any experience in commercial airplanes, and it relies heavily on western components. To be honest, it seems Sukhoi has been struggling with its latest military jet as well.
    Then there is the sub-par dispatch reliability and the poor service and spare parts network.

    The SSJ is just an attempt by the Russians to get back into the game. It was never going to be a state of the art game changer.
    it was a light dig at evan for playing it up in the ethiopian thread.

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