Announcement

Collapse
No announcement yet.

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

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    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

    Comment


    • #17
      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.

      Comment


      • #18
        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.

        Comment


        • #19
          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.

          Comment


          • #20
            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...

            Comment


            • #21
              Originally posted by ATLcrew View Post
              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...
              ...so you don't need to worry about it!
              Be alert! America needs more lerts.

              Eric Law

              Comment


              • #22
                Originally posted by ATLcrew 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...
                Hopefully they at least had some sort of CDU exceedences maintenance page.

                Originally posted by Airbus Safety First Magazine
                To protect turbine hardware, an operational limit on EGT (called “EGT red line”) is demonstrated during endurance tests required for FAR 33/JARE/ EASA engine certification. During such tests, the engine is run for 25 stages of 6 hours each. For each stage, the engine spends up to one hour cumulative time at max takeoff regime, with average EGT at redline conditions. Moreover, FAR 33 engine certification requires the engine to run for 5 minutes with N1 and N2 at red line levels and with EGT at least 42°C above the red line. After the run, the engine is disassembled and the turbine assembly must be within serviceable limits.
                This article is addressing how to avoid EGT overtemp on take-off, but it illustrates the need to take prolonged incidents of extreme exceedances very seriously. Even without an EGT indication, shouldn't this 767 scenario at the top of this thread lead you to conclude that a prolonged, extreme EGT exceedance has occurred (at least Area A, if not B or C, on the chart below) and that landing asap is the required move?
                Attached Files

                Comment


                • #23
                  There is one thing that doesn't seem to make much sense in that chart: lack of continuity. What's the difference between flying 4:59 at 949C and then reduce to 914C and flying 4:59 at 949C, then 0:02 at 451C, and then reduce to 414C? You bypass A and B and go straight to C for exceeding the EGT redline by 1 degree for 1 second?

                  --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                  --- Defend what you say with arguments, not by imposing your credentials ---

                  Comment


                  • #24
                    Originally posted by ATLcrew View Post
                    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...
                    Could those jets have been designed with some thought given to not be overly complex (and yes using some computer monitoring).
                    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                    Comment


                    • #25
                      Originally posted by 3WE View Post
                      Could those jets have been designed with some thought given to not be overly complex (and yes using some computer monitoring).
                      Or he uses TIT instead. TIT is more important that EGT. EGT is a "byproduct" of TIT. Imagine the EGT in an F-14 with afterburner. But the TIT remains under control.

                      --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                      --- Defend what you say with arguments, not by imposing your credentials ---

                      Comment


                      • #26
                        Originally posted by Gabriel View Post
                        Or he uses TIT instead. TIT is more important that EGT. EGT is a "byproduct" of TIT. Imagine the EGT in an F-14 with afterburner. But the TIT remains under control.
                        If you have a diminished flow of air to the cumbustors, thus diminished cooling and diminished 'shaping', resulting in excessive heat transfer to that section (and thus a rise in EGT), would the TIT reflect that?

                        Comment


                        • #27
                          Originally posted by Evan View Post
                          If you have a diminished flow of air to the cumbustors, thus diminished cooling and diminished 'shaping', resulting in excessive heat transfer to that section (and thus a rise in EGT), would the TIT reflect that?
                          Yes. TIT is the turbine INLET temperature. It is the temperature between the combustion chamber and the 1st turbine stage.
                          As the gas flows through he turbine and gives part of its energy to the turbine, the pressure and hence the temperature go down and result in a lower EGT after the last turbine stage.

                          The mixture of air and fuel is about stoichiometric in the beginning of the combustion chamber to make the combustion sustainable and more efficient, but then more air (that bypasses the first section) is added in the combustion chamber to get the temperature down to levels that are manageable by the turbine blades that are subject not only to temperature and aerodynamic loads but also to strong centrifugal loads due to their high rotation speed. If the flow of air is less than it should, that results in a too rich mixture in the beginning of the combustion chamber and then unburnt fuel. As more air is added to the gas (to cool it down), the unburnt fuel finds the missing O2 and burns, resulting in a higher gas temperature rather than lower). The TIT will be higher and so will be the EGT.

                          --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                          --- Defend what you say with arguments, not by imposing your credentials ---

                          Comment


                          • #28
                            Or put a little differently, the TIT is a direct measure of the temperature of the gases that are going to damage the turbine if the turbine is going to be damaged due to the temperature of said gases.
                            Be alert! America needs more lerts.

                            Eric Law

                            Comment


                            • #29
                              TIT EGT OAT CHT OT CT TT BT DT FT STP CT BT GT ST

                              https://www.youtube.com/watch?v=M1WemnsB98o
                              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                              Comment


                              • #30
                                Originally posted by Gabriel View Post
                                Yes. TIT is the turbine INLET temperature. It is the temperature between the combustion chamber and the 1st turbine stage.
                                As the gas flows through he turbine and gives part of its energy to the turbine, the pressure and hence the temperature go down and result in a lower EGT after the last turbine stage.

                                The mixture of air and fuel is about stoichiometric in the beginning of the combustion chamber to make the combustion sustainable and more efficient, but then more air (that bypasses the first section) is added in the combustion chamber to get the temperature down to levels that are manageable by the turbine blades that are subject not only to temperature and aerodynamic loads but also to strong centrifugal loads due to their high rotation speed. If the flow of air is less than it should, that results in a too rich mixture in the beginning of the combustion chamber and then unburnt fuel. As more air is added to the gas (to cool it down), the unburnt fuel finds the missing O2 and burns, resulting in a higher gas temperature rather than lower). The TIT will be higher and so will be the EGT.
                                Ok, but who monitors TIT? I'm talking about things the crew are alerted to or aware of. The standard indicators in most commercial jets are EPR, EGT, N1 and N2, at best. I'm pointing out that, during a continuous compressor surge event, you are going to get an EGT redline indication and what is the overtemp limit for continuing to destination vs landing asap? Or is this just not defined at all?

                                Comment

                                Working...
                                X