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Thread: Plane off runway in Trabzon, Turkey

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    Default Plane off runway in Trabzon, Turkey


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    Senior Member Gabriel's Avatar
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    Senior Member 3WE's Avatar
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    Quote Originally Posted by AvHerald
    ...the aircraft turned left, the aircraft went off the runway, the right hand engine suddenly accelerated in forward thrust unintentionally...
    What's it doing now?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Quote Originally Posted by 3WE View Post
    What's it doing now?
    This should be interesting...

    The forward thrust levers are locked and cannot be advanced from idle if the reverser levers are deployed. The EEC is a dual channel, fault-detecting design. I doubt it was to blame. Nothing else can advance forward thrust. I suppose if the reverser blocker door mechanism failed to deploy on the #2 engine, pulling up to full reverse would result in full forward thrust on that side, but I don't know if that is possible.

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    This should be interesting...

    The forward thrust levers are locked and cannot be advanced from idle if the reverser levers are deployed. The EEC is a dual channel, fault-detecting design. I doubt it was to blame. Nothing else can advance forward thrust. I suppose if the reverser blocker door mechanism failed to deploy on the #2 engine, pulling up to full reverse would result in full forward thrust on that side, but I don't know if that is possible.
    You cannot move each lever past idle reverse until the reverses are locked in place.
    Something like TAM maybe?

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    Quote Originally Posted by 3WE View Post
    What's it doing now?
    "the right hand engine suddenly accelerated in forward thrust unintentionally". That's the Captains story and he is sticking to it!

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    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    You cannot move each lever past idle reverse until the reverses are locked in place.
    Something like TAM maybe?
    So, the right reverser fails to deploy, thus the right reverser lever remains blocked, thus the right thrust lever remains unlocked and somebody accidentally moves it forward?

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    Quote Originally Posted by Evan View Post
    So, the right reverser fails to deploy, thus the right reverser lever remains blocked, thus the right thrust lever remains unlocked and somebody accidentally moves it forward?
    Should not be able to advance one if the other reverser is not stowed and locked.

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    Senior Member 3WE's Avatar
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    Quote Originally Posted by BoeingBobby View Post
    "the right hand engine suddenly accelerated in forward thrust unintentionally". That's the Captains story and he is sticking to it!
    In one of my rarer serious moments, that may actually be a valid story...To veer off the runway that strongly and that far down screams that something went wrong beyond the pilots control.

    Of course could the nosewheel hydraulic control valve gotten into a reverse-failure mode?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Quote Originally Posted by 3WE View Post
    In one of my rarer serious moments, that may actually be a valid story...To veer off the runway that strongly and that far down screams that something went wrong beyond the pilots control.

    Of course could the nosewheel hydraulic control valve gotten into a reverse-failure mode?
    Yes sir, and you know what else?Click image for larger version. 

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    Senior Member Evan's Avatar
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    BoeingBobby, you'd better warm up that pig...

    Not 'reversals', but uncommanded turns have occured at least 11 times already (7 on the B737).

    TSB Board concerned that runway overruns may continue if more is not done to understand uncommanded nosewheel steering events on Boeing aircraft

    Montreal, Quebec, 5 November 2013 – The Transportation Safety Board of Canada (TSB) today released its investigation report (A10Q0213) into the 30 November 2010 runway excursion of an American Airlines Boeing 737-800 at the Montreal/Pierre Elliott Trudeau International Airport.

    The aircraft was on a flight to Montreal, Quebec from Dallas, Texas with 113 people aboard. The aircraft landed normally on the wet runway in a crosswind. As the aircraft was slowing down, it veered, uncommanded by the crew, towards the left side of the runway. The captain, the pilot flying, tried using the rudder and the nosewheel steering tiller to steer the aircraft back to the runway centerline. Although the aircraft heading started to return back towards the runway heading, the aircraft continued to travel towards the left and exited the runway surface. There were no injuries, and damage to the aircraft was minor.

    Investigators found that the uncommanded veer to the left of runway centerline was likely due to a jam in the nosewheel steering system. Following the occurrence, investigators did not find any anomalies with the nose-gear wheel system, as the jam likely cleared up. The flight crew did not receive any indication that a problem existed with the nose-gear steering system, nor are there any written procedures to manage a nosewheel steering problem of this kind. The aircraft’s flight data recorder (FDR) does not record parameters from the nosewheel steering system, thus making it difficult to determine when and how problems with nosewheel steering occur.

    There have been 11 similar occurrences reported involving various Boeing aircraft types in the past 21 years throughout the world. The cause of these uncommanded nosewheel steering occurrences remains uncertain, despite post-event examinations and other efforts to analyze them. The manufacturer’s safety review process has deemed these occurrences to be an acceptable risk given their remoteness, and the manufacturer has not taken further action to correct them. As their cause is uncertain, and because little is being done to better understand the problem, the Board is concerned that there remains a risk for runway excursions to occur.

    Following the accident, American Airlines now discusses this occurrence as part of recurrent training for its flight crews. This training is given to the flight crews to raise awareness of the possibility of a runway excursion due to a nosewheel steering problem after landing.


    The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

    For more information, contact:
    Transportation Safety Board of Canada
    Media Relations
    Yes, another of the 737's brushed under the carpet issues. Yet another jam which leaves no trace, allowing the company to deny that a problem exists, for now.

    Or maybe up until now...

    Full report: http://tsb.gc.ca/eng/rapports-report...3/a10q0213.asp

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    So, the right reverser fails to deploy, thus the right reverser lever remains blocked, thus the right thrust lever remains unlocked and somebody accidentally moves it forward?
    Well, in TAM what happened is that the right thrust lever was not retarded and the plane didn't go to GROUND mode so the AT didn't automatically disengage so the AT started to add thrust on the right engine trying to keep the approach speed. That was an Airbus and this is a 737, so will not be exactly the same, but perhaps something more or less similar?

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    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Well, in TAM what happened is that the right thrust lever was not retarded and the plane didn't go to GROUND mode so the AT didn't automatically disengage so the AT started to add thrust on the right engine trying to keep the approach speed. That was an Airbus and this is a 737, so will not be exactly the same, but perhaps something more or less similar?
    If the plane remains in flight mode, the reversers also won't deploy and the lever at idle will still be commanding flight idle. I think things would have ended more catastrophically in that case but maybe...

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