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Thread: Air Zimbabwe 767 Engine Surge, Tailpipe Flames, Mayday... Continues to Destination

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    Senior Member Evan's Avatar
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    Default Air Zimbabwe 767 Engine Surge, Tailpipe Flames, Mayday... Continues to Destination

    No harm, no foul?

    http://avherald.com/h?article=4c7467ca&opt=0


    So... question: is there an EGT threshold after which you must land asap?

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    I'd say the answer is a qualified "yes" but you missed a step.

    There's probably an EGT threshold above which the engine must be shut down. In that case you'd of course (in this aircraft) be flying single-engine which probably would mandate landing.

    There's a gray area I can picture: if the engine is damaged such that at a normal power setting the EGT is too high, but the EGT can be brought within limits by reducing the power. I'm not sure whether there's any specific guidance on whether to continue or terminate a flight in those circumstances. It seems like termination would be the safe choice, as if the engine is damaged, there may be things going on that that could cause it to fail completely later on.a
    Be alert! America needs more lerts.

    Eric Law

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    Senior Member Evan's Avatar
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    Quote Originally Posted by elaw View Post
    I'd say the answer is a qualified "yes" but you missed a step.

    There's probably an EGT threshold above which the engine must be shut down. In that case you'd of course (in this aircraft) be flying single-engine which probably would mandate landing.

    There's a gray area I can picture: if the engine is damaged such that at a normal power setting the EGT is too high, but the EGT can be brought within limits by reducing the power. I'm not sure whether there's any specific guidance on whether to continue or terminate a flight in those circumstances. It seems like termination would be the safe choice, as if the engine is damaged, there may be things going on that that could cause it to fail completely later on.a
    I would think it would be as serious as a hot start on a turbine helicopter. That is generally understood to require a shut down and a subsequent teardown inspection before the engine can be considered airworthy again. So, if a twin-engine airliner experiences a very high EGT due to a prolonged engine surge (in this case 60-90 seconds of flame exiting the engine), even if it recovers it would be considered unsafe and, with only one engine considered safe, a return would be required.

    I just wonder if there is some written (or unwritten) rule, recommendation or policy about that.

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    Senior Member Gabriel's Avatar
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    ANy indication that the EGT was too high? The tailpipe fire can be unburned fuel burning when it gets out of the engine.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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    Senior Member Evan's Avatar
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    No, not directly, but the reports suggest this was a continuous surge of 1-2 minutes where axial flow would be disrupted but combustion wasn't and was thus flaming out the tailpipe and you would expect a high EGT indication as a result. There are AFM limits for EGT during a hot start so I would expect similar limits for a continuous surge in flight. AFAIK, EGT can rise about 5C per second during a minor surge to about 15C per second for an unrecoverable one. We're talking about 60-90 seconds here, and they recovered (or it self-recovered) and continued another 90 mins to destination despite being about 10mins from departure.

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    No, not directly, but the reports suggest this was a continuous surge of 1-2 minutes where axial flow would be disrupted but combustion wasn't and was thus flaming out the tailpipe and you would expect a high EGT indication as a result.
    I would expect high TIT.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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    This is going to require a very large popcorn and maybe a pizza too. Carry on.

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    Senior Member Evan's Avatar
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    Quote Originally Posted by BoeingBobby View Post
    This is going to require a very large popcorn and maybe a pizza too. Carry on.
    Why don't you put it aside and tell us from experience? Is there a point at which the engine is considered compromised and warranting a return or diversion? Is running it back up after that point and continuing to climb risking a more catastrophic failure?

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    Quote Originally Posted by Evan View Post
    Why don't you put it side and tell us from experience? Is there a point at which the engine is considered compromised and warranting a return or diversion? Is running it back up after that point and continuing to climb risking a more catastrophic failure?
    Look it up on the internet. You are so good at it. I might give you the wrong info like with the RTO brakes. Meantime, I am putting the Orville Redenbacher on the stove.

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    Senior Member BoeingBobby's Avatar
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    In the 74, loosing an engine is not that big of a deal. Got 3 more!

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    Senior Member Gabriel's Avatar
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    Quote Originally Posted by BoeingBobby View Post
    In the 74, loosing an engine is not that big of a deal. Got 3 more!
    But in the DC-3? If you have one engine running rough, delivering significantly less than rated power, coughing and sputtering fire through the exhaust during a couple of minutes, and then it recovers...

    Would you say it is wise to land or is it ok to cross the ocean?

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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    Senior Member 3WE's Avatar
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    Quote Originally Posted by BoeingBobby View Post
    Look it up on the internet. You are so good at it. I might give you the wrong info like with the RTO brakes. Meantime, I am putting the Orville Redenbacher on the stove.
    How are we going to admonish the pilots unless we can find that they did something wrong?

    AND am I to understand that you make popcorn in a pan, instead of an electrical corn popper with some automatic shutoff features? Sounds dangerous to me, and we don't like burnt kernels.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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    Senior Member BoeingBobby's Avatar
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    Quote Originally Posted by Gabriel View Post
    But in the DC-3? If you have one engine running rough, delivering significantly less than rated power, coughing and sputtering fire through the exhaust during a couple of minutes, and then it recovers...

    Would you say it is wise to land or is it to cross the ocean?
    Different animal, I have brought more than one DC-3 back to MIA on one, and quite a few DC-6's back on 3 and a couple of times on two!

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    Quote Originally Posted by 3WE View Post
    How are we going to admonish the pilots unless we can find that they did something wrong?

    AND am I to understand that you make popcorn in a pan, instead of an electrical corn popper with some automatic shutoff features? Sounds dangerous to me, and we don't like burnt kernels.
    Stove top is much better in my opinion.

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    Quote Originally Posted by BoeingBobby View Post
    Stove top is much better in my opinion.
    agreed!

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    Quote Originally Posted by BoeingBobby View Post
    Stove top is much better in my opinion.
    I'm disappointed... I thought you were going to say it's best cooked in a pan sitting on the exhaust pipe of an R-1830.
    Be alert! America needs more lerts.

    Eric Law

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    Quote Originally Posted by BoeingBobby View Post
    This is going to require a very large popcorn and maybe a pizza too. Carry on.
    Two slices with spicy sausage and green peppers for me, please and thank you.

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    Quote Originally Posted by Evan View Post
    AFAIK, EGT can rise about 5C per second during a minor surge to about 15C per second for an unrecoverable one.
    Source, please. I'm genuinely curious, never seen definitive numbers like that before.

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    Senior Member Evan's Avatar
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    Quote Originally Posted by ATLcrew View Post
    Source, please. I'm genuinely curious, never seen definitive numbers like that before.
    https://www.google.com/url?sa=t&rct=...-nugf3AWgyD3KC

    Scroll to page 11.

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    Quote Originally Posted by Evan View Post
    Interesting article, thanks. They don't really explain how they came up with those (and other) numbers, and seem to use the word "should" a lot without backing it with much, but alas...

    Then there's the matter of me having spent six years flying a family of jets that had neither an EGT, nor an EPR indication...

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