Ethiopian Airways flight crashes (10/03) + 737 MAX grounding

Discussion in 'Other Public Transport' started by atillathehunn, 10 Mar 2019.

  1. atillathehunn

    atillathehunn Established Member

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    An Ethiopian Airlines flight has crashed shortly after take off from Addis bound for Nairobi.

    All 157 souls are lost.

    The Boeing 737MAX8 now has its second fatal accident within a few months.

    A devastating loss.

    I fly this route regularly. A sobering thought.

    https://www.bbc.com/news/world-africa-47513508

     
    Last edited by a moderator: 11 Mar 2019
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  3. bignosemac

    bignosemac Established Member

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    Boeing will be concerned. Two complete hull losses of the 737MAX in a few months. Both shortly after take-off.
     
  4. LOL The Irony

    LOL The Irony Established Member

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    Blame the culture that came with them buying McDonnell Douglas. Building aircraft to sell rather than fly.
     
  5. YorkshireBear

    YorkshireBear Established Member

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    Does it feel similar to the lion air crash? Seems it from the limited information I've seen.

    Also incredible the variety of nationalities
     
  6. berneyarms

    berneyarms Established Member

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    Not really that incredible about the nationalities - there’s a UN conference starting in Nairobi this week.

    Regardless of that Ethiopian are a major hub airline for the African continent through Addis Ababa.
     
  7. TheEdge

    TheEdge Established Member

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    I see Ethiopian has already grounded the remainder of its 737MAX fleet and China has banned them from their airspace. Although that might be more political than anything.

    It may turn out to be absolutely unrelated to the Lion Air crash but it doesn't really look good for Boeing to have lost two MAXs in such quick succession.
     
  8. AM9

    AM9 Established Member

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    It seems that attention is being focused on the Maneuvering Characteristics Augmentation System (MCAS) as both of the crashes were preceded with unstable climb rates and angles of attack. The system is intended to prevent stalls that Owing to the larger bypass fans needing to be mounted higher to achieve minimum ground clearance, they have been raised into the wings leading edge profile. This has changed the aerodynamics of the wing/airframe and consequently created a tendency for tail heavy flight attitudes particularly likely during climbing after takeoff. I would imagine that Boeing will already be creating scenarios that look for systematic failures in that area. The MCAS was already under investigation following the Lion Air crash.
     
  9. Bletchleyite

    Bletchleyite Veteran Member

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    Small Boeings typically sit far lower than Airbuses (hence the "hamster cowl" on the engines) - I wonder why they went for all this complexity rather than just making the landing gear a bit taller?
     
  10. AM9

    AM9 Established Member

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    It seems that in their quest to undercut the operating cost of the A320neos by using a larger bypass fan, they took a compromise in the engine location. As you say, the 737 has always had the shortest undercarriage that they could get away with and in this case, in order to maintain the 17 inch clearance below the engine nacelle, an extension to the front undercarriage strut would have involved extensive airframe modifications to accomodate it when raised which would have put both the production cost and the weight up. The (less costly) solution chosen was to partially extend the strut and mount the engines further forward and higher on the wing. This necessitated a laminar flow spun nacelle lip similar to the 787 design. For the 737 max10, the front strut has been extended further with a lever arrangement that shrinks it's length as it rises so that the existing stowage bay can accommodate it. The net result of the engine relocation on all the maxs is a tendency to go nose up which requires measures to lift the tail. The MCAS was put there to reduce the pilot's involvement in that.
     
    Last edited: 11 Mar 2019
  11. TheEdge

    TheEdge Established Member

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    As a total layman maybe certain alterations would require a different type rating or similar. Although that's a total guess!
     
  12. AM9

    AM9 Established Member

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    I don't think so, - tweaks to enhance the performance against the competition are intended to cause as little (design) disruption as possible. The certification of design changes is against a full engineering case. Boeing, like Airbus make decisions against previous design baselines, qualifying not only the new part(s) but also ensure system integrity is as intended. In the race to compete though, it is inevitable that some things are overlooked, and occasionally, new failure modes (that weren't expected) arise. Fortunately, they rarely get attention outside the industry but something as big as this attracts widespread scruting, and rightly so.
     
  13. edwin_m

    edwin_m Veteran Member

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    I would have thought raising the centre of thrust with the engines would create a tendency to go nose down?
     
  14. Bletchleyite

    Bletchleyite Veteran Member

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    Think about it this way - the aircraft pivots around the wing, effectively (as that's the bit that's holding it up), so a force below the wing will make the nose go down. If you move the force closer to the wing, that effect will reduce. Move it above and it'll go up.

    So I guess it's more a reduced tendency for the nose to go down?

    The elevators at the back push the tail down (by pushing air up) to counter this effect, they aren't a second wing in the sense of keeping the plane up.
     
  15. atillathehunn

    atillathehunn Established Member

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    My workplace has banned flights on the 737MAX8 (an agency within the UN). It isn't UN policy, but a local initiative.
     
  16. 73001

    73001 Member

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    Thank you for a concise explanation of the issues... I also read Airliners.net and gave up on their thread after 20 pages of complete guesswork, repetition and childish comments. Obviously we have no idea at the minute but at least I now understand why there might be an issue and what it might be.
     
  17. AM9

    AM9 Established Member

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    Yes, I think the problem isn't so much the increased tendency for the nose to go up, - most pilots will be trained to deal with an aircraft that is approaching a stall, (then there's nagging Nora shouting it out anyway), but Boeing fitted the MCAS to provide some auto correction. This feature may have been malfunctioning on the Lion Air flight and to make matters worse, the crew hadn't been trained on it's use, so they were trying to correct an effect caused by a system that they didn't know existed and might have been faulty anyway. If true, in a nightmare situation like that, the crew didn't stand a chance.
     
  18. Swanny200

    Swanny200 Member

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    It does make me wonder is this is Boeing's Airbus moment where they implement something in their new aircraft and neglect to tell the people that pilot them how it all works: see the Air France 296 crash in 1988. (Boeing had originally said in some reports that they didn't want to overload pilots technically with the differences), these pilots have some from 737's whereas the 737 Max is a completely different plane.
     
  19. jellybaby

    jellybaby Member

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    Can you be sure what aircraft you will get until you get to the gate?
     
  20. Bletchleyite

    Bletchleyite Veteran Member

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    You can always decline to board. You'll lose your fare, but if the company is paying...
     
  21. TheEdge

    TheEdge Established Member

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    Most (if not all) airlines openly list the aircraft booked on each flight, sometimes even down to if its a 737-800 or 737-900 so you can tell what you get. Necessity also means most aircraft allocations are fairly solid.

    Well the more obvious example would be Kegworth, as that was a new family of 737s with a modification over the last generation, in that case swapping the engine the bleed air was drawn from on the 737 Classic than it was on the 737-1/200s.
     
  22. Swanny200

    Swanny200 Member

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    Yes of course I forgot all about Kegworth, IIRC they powered down the wrong engine, because if you smelt burning through the flightdeck vents on the 737 classic it denoted that the right engine was at fault when in fact it was the left at fault on the newer model, how such a simple change in some respects had caused the downing of a plane.
     
  23. edwin_m

    edwin_m Veteran Member

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    Looking at it from the port wingtip, it is flying right to left and applying forward (leftward) force to the engines (equal and opposite reaction to the thrust) in the absence of any correction will surely rotate it clockwise therefore nose up? And if the same force is applied closer to the wing the nose won't go up so much?
     
  24. Bletchleyite

    Bletchleyite Veteran Member

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    You're actually right, I was being thick. Must be something else related to weight/balance then.
     
  25. edwin_m

    edwin_m Veteran Member

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    Bringing the heavy engines further forward would also create a tendency to go nose down. They haven't by any chance stretched the rear part of fuselage?
     
  26. rdeez

    rdeez Member

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  27. Bletchleyite

    Bletchleyite Veteran Member

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    That makes a very interesting and slightly chilling read. It certainly gives the impression, to be blunt, of "we screwed up designing the shape of the engine nacelle, and it caused an unexpected issue in flight, so we bodged on a system to work around it instead of fixing it properly because it was cheaper than binning a load of metal we'd already built and doing it again properly".

    This is rather concerning as an attitude from an aircraft manufacturer.
     
  28. rdeez

    rdeez Member

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    In theory, it seems like a reasonable solution to a potentially very expensive problem, if you would otherwise end up redesigning large chunks of the fuselage - the MCAS is only supposed to be required in a small number of situations and flight envelope protections are found in most modern aircraft. From what I've read though, it seems like the implementation and particularly how it was (or wasn't, as it turned out) communicated to pilots left a lot to be desired. Boeing are "all in" with the 737 MAX with thousands of orders on the books - even if this crash did turn out to be related to MCAS as well, I can't see them going back to the drawing board on the entire aircraft, it could ruin them. More likely extensive modifications to the system and further training for pilots.
     
  29. TheEdge

    TheEdge Established Member

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    So Singapore has now banned the entire MAX family, as opposed to the MAX 8 only, from their airspace.

    I'd imagine the Boeing boardroom isn't a happy place at the moment.
     
  30. thejuggler

    thejuggler Member

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    An American Airlines 737 Max pilot was on R4 yesterday and he also discussed the matter of the system being installed, but its existence not being revealed to pilots as they wouldn't be aware it was operating. There was fear of overloading pilots with too much information. His familiarity training was an ipad app training course which took him 56 minutes.

    He did however state it is great aircraft to fly, but this was a serious omission by Boeing and he feels it was done to show the new aircraft isn't that much different in order to keep customers away from the 320 Neo.
     
  31. YorkshireBear

    YorkshireBear Established Member

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    More countries added to the list that have prohibited 737MAX operation, Singapore and Australia this morning.
     

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