MD-87 in flames in Houston field, all occupants apparently evacuated

Discussion in 'Aviation Mishaps' started by MFE, Oct 19, 2021.

  1. MFE

    MFE Pre-Flight

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    I drove past the memorial for that crash a couple weeks ago. IIRC there was speculation, if not outright confirmation, that the crew had pulled the circuit breaker for, or otherwise disabled, the configuration warning horn because it often sounded during taxi or something, and was an annoyance. Re-enabling it is not on the checklist. So they had no warning that they had not configured the plane properly for takeoff. It did not get very far.
     
  2. azpilot

    azpilot Line Up and Wait

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    So, I have a question about the Flight 255 crash. I'm a lowly private pilot that just crossed 200 hours. The largest thing I've ever flown in a 182. As you might imagine, I'm very accustomed to taking off with no flaps. What would the flaps setting be for takeoff in a MD-82? How much does that change the stall speed? I just don't understand why that would cause the plane to crash. Wouldn't you just feel that the plane is on the verge of stalling and push the nose down? Can someone help educate me on this?
     
  3. Bill

    Bill Touchdown! Greaser! PoA Supporter

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    While our GA flaps do increase drag and lift, they do not greatly increase wing area. Likewise there is not a great difference between clean and full flaps stall speeds.

    on transport aircraft flaps/slats do greatly alter wing area and the difference between clean and full flaps stall speeds are large.

    Net: A transport airplane not configured for takeoff will not generate enough lift at typical takeoff speeds.
     
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  4. Tools

    Tools Pre-takeoff checklist

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    Another way to look at it is that most JETS need flaps, period. A huge factor that allows them the speed they attain is a thin wing that doesn’t generate much lift unless at incredible speeds.

    Frankly, these things have enough performance margin that if the pilots had the experience (that current training doesn’t allow for) to know what it felt like trying to rotate without flaps, they could simply reach down, extend them and press safely.

    In a GA plane I’m used to using flaps in, it’s IMMEDIATELY obvious and I simply reach down and extend them...

    It’s a cultural thing, the incredible reliance on procedure means they basically have little air sense. It’s a double edged sword though... under reliance on massive checklists in that environment creates the sorts of problems that have largely gone away.

    As usual, the best option is somewhere in the middle. In part 121 the pendulum is headed back the right direction.
     
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  5. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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  6. 3393RP

    3393RP En-Route

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    Yeah, if those undertrained ATPs on NW 255 had deployed the flaps and slats while accelerating to take off (and waited the twenty seconds or so required to extend them), they would have safely flown away. Well, except the aircraft would have gone off the runway end and crashed anyway, long before the lift devices could extend.

    But they really didn't have any idea or feel for what the plane was doing, so there was that problem.
     
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  7. azpilot

    azpilot Line Up and Wait

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    Quotes from some of the passengers:

    https://www.cnn.com/2021/10/20/us/texas-plane-crash-wednesday/index.html

    "Going down the runway, and it just all the sudden they slammed on the brakes," the passenger, who didn't want to be named, told KHOU.

    "Things were flying around and when it finally came to a stop, they just said 'Get out, get out' because we thought it was going to explode," the man said. "It was already on fire before we got out of it!"
     
  8. Stan Cooper

    Stan Cooper Pattern Altitude PoA Supporter

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    Does the MD-87 have the same horizontal stabilizer trim jackscrew the MD-80 has?
     
  9. KSCessnaDriver

    KSCessnaDriver Pattern Altitude

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    I wouldn't have a care in the world about a DC-9 type airplane on 6000 ft.
    There is no such thing as an MD-80, that's the series marketing name. There is an MD-81/82/83/87/88. Technically, they're DC-9-81/82...
     
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  10. Tools

    Tools Pre-takeoff checklist

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    And a -90. Ya, pretty sure they all have the same jack screw. The -90 and 717 have powered elevators, but still pretty sure the same trim jack screws.
     
  11. midwestpa24

    midwestpa24 En-Route

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    Flap settings are critical in jet aircraft. Normal rotation speed depending on type, weight, etc. can be 120-150 kts. Without flaps it would need to be over 200 kts. Same on landing, a flapless landing in a jet aircraft is usually considered an emergency landing due to the high speeds that they will need to maintain on landing.
     
  12. azpilot

    azpilot Line Up and Wait

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    Those numbers really help to put it in perspective, thank you. I'd imagine that given a long enough runway, in ideal weather conditions, you could make it work. But if you're expecting to come off the ground at 120 - 150 kts, and it doesn't want to fly until 200 kts, that will be a problem.
     
  13. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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  14. AKBill

    AKBill En-Route

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  15. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    Trailing Edge Down?
     
  16. Everskyward

    Everskyward Experimenter PoA Supporter

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    I had to read the article to learn that...
     
  17. Tools

    Tools Pre-takeoff checklist

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    Weird. They’re not connected to anything, even each other!

    So both jammed down is some BAD juju. A control check won’t detect that. Even an exterior view of a control check won’t. I can only imagine if the plane was sitting a long time, they just corroded in place, as they would just hang on their own.
     
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  18. Tarheelpilot

    Tarheelpilot Final Approach PoA Supporter

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    Same thing happens to the (I think) kalitta charters airplane. High speed abort after v1 because of mechanical failure of the elevator from damage in high winds.
     
  19. aggie06

    aggie06 Pre-takeoff checklist

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    Report indicates the linkage was over center, so I don’t think corrosion is the issue.
     
  20. Fearless Tower

    Fearless Tower Touchdown! Greaser!

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    It was Ameristar and the photos of the bent linkages in the two airplanes are virtually identical.
     
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  21. Tools

    Tools Pre-takeoff checklist

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    That makes sense, as they just flop around on the ground. And they’re two stories or more up, not like you can check them during preflight.
     
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  22. FlyingTiger

    FlyingTiger Pre-takeoff checklist

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    They may have had a hint something was up prior to V1 when the auto throttles wouldn't engage. Takeoff mode was another item on the missed checklist. They corrected that while accelerating but unfortunately it didn't tip them off to the bigger problem. Terrible accident but a good review for pilots at all levels.
     
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  23. Davecat

    Davecat Pre-Flight

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    This will educate the nuances of the elevator design.

     
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  24. Larry in TN

    Larry in TN Pattern Altitude

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    All of the DC9-series, including all of the MD80s, MD90s, and B717, are the same. They do not require flaps (if the runway is sufficiently long), but they do require the leading-edge slats for takeoff. To shorten the runway required you add flaps to the slats-extended takeoff configuration, at the expense of second-segment climb. Without the slats, the takeoff speed would be unreasonably high and not obtainable on most runways.

    I haven't flown a DC9 since 2009 so I don't remember the speeds. The 737s, that I fly now, will typically have clean-maneuvering speeds a little over 200 KIAS, depending on weight. You wouldn't need to make it to quite that speed for takeoff, but it would be a very long takeoff roll.


    It does, but that's for trimming the stabilizer. It has nothing to do with the elevator operation.

    You do a control check at 80kts on takeoff by pushing the yoke and noting the nose dip. That ensures that the elevators are moving free and the control tabs are working.

    The same system is used on the DC8. The elevators are "flown" by the control tabs. Yoke movement moves the control tabs via cables and pulleys. The control tabs move the elevators with aerodynamic forces.

    Due to it's t-tail configuration, the DC9 also has a hydraulic actuator on the elevators but it only activates in a deep stall situations where the wings are blanking airflow over the tail and preventing the control tabs from moving the elevators. It wouldn't have been a factor on takeoff. The elevator power system is tested with a control check during taxi-out.
     
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  25. BladeSlap

    BladeSlap Pre-takeoff checklist

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    Cool they keep those old birds flying, Commemorative Air Force?
     
  26. Stan Cooper

    Stan Cooper Pattern Altitude PoA Supporter

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    I understand that; I've never flown a large turbine transport plane and am probably showing my ignorance, but if the stabilizer trim jackscrew were somehow jammed with the angle of incidence forcing a nose down attitude, wouldn't it be possible the elevator controls couldn't be enough to permit rotation?
     
  27. kayoh190

    kayoh190 Administrator Management Council Member PoA Supporter

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    They'd know when they set the trim for takeoff, which generally happens right after they get their final weight and balance data.
     
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  28. Stan Cooper

    Stan Cooper Pattern Altitude PoA Supporter

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    Ahh... thanks!
     
  29. Juliet Hotel

    Juliet Hotel En-Route

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    Linkages were bent and over-centered. There was another accident due to this. I believe excessive winds while parked causing the elevators to slam too hard against the stops is usually the cause.
     
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  30. Tools

    Tools Pre-takeoff checklist

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    Gotta fair amount of time in these, never even heard of that... hmmm... might have been nice to know.

    After all I am familiar with the two mirrors required to use the wet compass over the copilots shoulder, THATS important... geesh.
     
  31. Tantalum

    Tantalum Final Approach

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    Exactly. Blancolirio posted a good video about this a few days ago with footage of the linkages bending during tests etc..
     
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  32. Davecat

    Davecat Pre-Flight

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    Bingo....photos of the linkage in Blnacolirio's update