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  • AD for A320 for excessive forces causing separation of tailplane

    It would happen sooner or later: A plane telling the pilot "get your limbs off my controls".

    Consequently, EASA issued AD 2014-0217 to require installation and activation of the stop rudder input warning (SRIW)
    http://avherald.com/h?article=48fd2e64&opt=0

    I am still waiting for the "Gimme my friggin plane back!" button for the pilot to override H.A.L. (and SRWI).

    --- 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 ---

  • #2
    COOL...more acronyms and associated procedures and QRH memory checklists.

    Is it valid to compare the number of cheap composite rudder incidents (and rudder induced cheap C-130 over-stress incidents) with the number of near total almost didn't (and actually didn't) takeoff disasters and suggest TOPMS to adress the fact that the V1 system is sometimes fallible...and establish V3BS for all those tragic over runs?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

    Comment


    • #3
      Originally posted by Gabriel View Post
      It would happen sooner or later: A plane telling the pilot "get your limbs off my controls".


      http://avherald.com/h?article=48fd2e64&opt=0
      Good. It's about time. The plane has to defend itself—and us— against idiocy.

      It's a very sad and disturbing age when pilots cannot be expected to understand the basic idiocy of rudder reversals on large aircraft. Yet this is the age we live in. Mass-produced pilots. After repeated instances of pilot idiocy taking massive amounts of lives, we are forced to design planes that will give pilots lessons on the fly and even take authority away from them.

      The rudder on a large transport aircraft is there for turn coordination (which often requires no pilot inputs), moderate sideslip manuevers and thrust assymetry. It's not a primary flight control for roll excursions. And it certainly is not there to be wagged around by improvising pilots.

      Why react to this by directing animosity towards Airbus? First of all, we know that there is no issue with the composite strength of the tailplane mounts (they held on AF447 and have failed on Boeing aircraft where lateral forces similar to the ones experienced by AA587 were encountered). This is not a design problem in need of a design solution, it's a pilot training issue. But at least Airbus is taking measures to protect the public.

      That should be the job of the CAA's and the operators. But sometimes, when the law fails to act, you have to take matters into your own hands.

      Comment


      • #4
        How do you know that it held on AF447 ? BEA report say that the aircraft impacted belly down nose up. According to the report the tail hit the water first at a vertical speed of more than 200 km/h, but the tailfinn was floating around in the Atlantic nearly undammaged. if it came down separately it is understandable but not as the first part that hit the water ?

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        • #5
          Originally posted by Thom View Post
          How do you know that it held on AF447 ? BEA report say that the aircraft impacted belly down nose up. According to the report the tail hit the water first at a vertical speed of more than 200 km/h, but the tailfinn was floating around in the Atlantic nearly undammaged. if it came down separately it is understandable but not as the first part that hit the water ?
          The BEA report explains very well how the fin (in fact the fin supporting structure, which was still attached to the fin) was torn forward when the plane hit the water.

          --- 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


          • #6
            Originally posted by Gabriel View Post
            It would happen sooner or later: A plane telling the pilot "get your limbs off my controls"...

            ...I am still waiting for the "Gimme my friggin plane back!" button for the pilot to override H.A.L. (and SRWI)...

            Indeed.


            I wonder what the general opinion is on this in the Twittersphere?
            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

            Comment


            • #7
              Originally posted by Evan View Post
              Why react to this by directing animosity towards Airbus? First of all, we know that there is no issue with the composite strength of the tailplane mounts (they held on AF447 and have failed on Boeing aircraft where lateral forces similar to the ones experienced by AA587 were encountered). This is not a design problem in need of a design solution, it's a pilot training issue. But at least Airbus is taking measures to protect the public.
              Ok, here you lost me.

              1- What does AF447 have to do with this? Yes, the rudder also held in 9/11. And?
              2- When have a tail fin failed on Boeing aircraft where lateral forces similar to the ones experienced by AA587 were encountered?
              3- Additionally to the regulatory requirement (at Va, suddenly apply and keep full rudder input to overswing limit, then let it settle at max steady sideslip limit, then suddenly center the rudder, all with a safety factor of 1.5), unlike Airbus, Boeing had its own internal requirement to suddenly apply full rudder and then, at the point of max overswing, suddenly apply full opposite rudder, albeit with a safety margin of 1.2.

              --- 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


              • #8
                Originally posted by Gabriel View Post
                Ok, here you lost me.

                1- What does AF447 have to do with this? Yes, the rudder also held in 9/11. And?
                2- When have a tail fin failed on Boeing aircraft where lateral forces similar to the ones experienced by AA587 were encountered?
                3- Additionally to the regulatory requirement (at Va, suddenly apply and keep full rudder input to overswing limit, then let it settle at max steady sideslip limit, then suddenly center the rudder, all with a safety factor of 1.5), unlike Airbus, Boeing had its own internal requirement to suddenly apply full rudder and then, at the point of max overswing, suddenly apply full opposite rudder, albeit with a safety margin of 1.2.
                1) Despite tremendous impact forces that ripped apart the metal supporting structures, the composite tailplane mounts did not fail. So I don't want to hear another word about 'cheap composites'.

                2) There have been ten incidents of tailplane failure on modern aircraft due to structural overload or pneumatic force.

                Nine of these ten have involved non-Airbus, non-Composite structures:

                China Airlines 611, Boeing 747, tailplane blown off by pneumatic force.
                JAL 123, Boeing 747, tailplane blown off by pneumatic force.
                Widerøe Flight 933, Twin Otter, tailplane departed due to clear air turbulence.
                Braniff 250, BAC 1-11-203AE, tailplane departed due to turbulence
                BOAC 911, Boeing 707, tailplane departed due to clear air turbulence
                4 x Boeing B52 loss of tailplane incidents due to structural failure

                But yes, because one of ten did involve the Airbus composite structure, let's place all our concern there.

                3) I believe the Airbus design meets the regulatory requirement. AA 587 did not "let it settle at max steady sideslip limit". What occurred was sudden rudder reversals to the mechanical stop. If Boeing has designed their planes to handle this (which I highly doubt), great, but why? No pilot in their right mind should ever even think about doing this. Again, this is basic threshold exceedance: VA, the maximum speed, at a given weight and configuration, at which any one flight control surface can be abruptly and fully deflected—not to include rapid control surface reversals—without causing aircraft damage.

                Rapid control surface reversals = pilot idiocy. Thus we have the idiocy-proofing. Unfortunately, this is the industry solution to the problem of low pilot-certification standards.

                Comment


                • #9
                  Originally posted by Evan View Post
                  ...pilot idiocy... idiocy-proofing....low pilot-certification standards.
                  Trolling a bit, are we?

                  This response may have to suffice.
                  Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                  Comment


                  • #10
                    Evan,

                    Have you ever thought that applying right rudder might be, for some pilots, a natural reaction upon an unwanted and uncommanded (or so they think) left yaw/sideslip?

                    PIO, once started, is one of the hardest things to correct promptly and correctly, because the initial P is part of the problem.
                    And of course, being able to apply full rudder with just 1 inch of pedal deflection and a force that is a pound beyond the friction breaking force doesn't help.
                    And neither does threatening the pilots during training about risks of rolling inverted upon the encounter of wake turbulence and the importance of using the rudder to recover from a sure death.
                    Or the fact that it had been identified that the pilot was over-aggressive with the rudder and nobody had done anything about it.
                    Or the fact that Airbus didn't go beyond the requirements as Boeing did to foresee the possibility that a pilot might react to a left sideslip with right rudder.
                    Nor the fact that there was a generalized belief that you cannot break a plane from aerodynamic forces below Va.

                    I'd say that "pilot idiocy" is way an over-simplification and a tad unfair. Not that there was not some of that, but there was much more than that.

                    Finally, the 747 fins that were blown due to pneumatic force don't qualify as lateral forces similar to the ones experienced by AA587.
                    Neither does the 707 in Mount Fiji, that was flying way waaaaay faster than Va (and than turbulence penetration speed too, by the way). The lateral forces were not similar other than they were lateral and they were forces. But that is like saying that mouse is a quadruped mammal similar to an elephant.

                    --- 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


                    • #11
                      Originally posted by Gabriel View Post
                      Evan,

                      Have you ever thought that applying right rudder might be, for some pilots, a natural reaction upon an unwanted and uncommanded (or so they think) left yaw/sideslip?

                      PIO, once started, is one of the hardest things to correct promptly and correctly, because the initial P is part of the problem.
                      And of course, being able to apply full rudder with just 1 inch of pedal deflection and a force that is a pound beyond the friction breaking force doesn't help.
                      And neither does threatening the pilots during training about risks of rolling inverted upon the encounter of wake turbulence and the importance of using the rudder to recover from a sure death.
                      Or the fact that it had been identified that the pilot was over-aggressive with the rudder and nobody had done anything about it.
                      Gabriel, we agree on all of this. The AA587 investigation discovered that pilots were getting not only a lack of proper training on the use of rudder, but also dangerously bad training on the use of rudder. Pilots of wide-body aircraft with no risk of extreme roll excursions in wake turbulence were being trained on small jet simulators and—yes!—threatened about risks of rolling inverted upon the encounter of wake turbulence and the importance of using the rudder to recover from a sure death. That simply won't happen in an A300, and no rudder input is needed to safely transit the turbulence. And—yes—apparently nothing much had been done about this lack of understanding on the use of rudder on large transport aircraft. However, PIO can be avoided with proper training.

                      Or the fact that Airbus didn't go beyond the requirements as Boeing did to foresee the possibility that a pilot might react to a left sideslip with right rudder.
                      Here's where you lose me. Airbus designs MEET the requirements set out by the FARs. If those requirements are not adequate, it's the FARs that needs to be addressed. Secondly, Airbus rudders ARE completely safe when used to the mechanical stop (or blowback limit) in one direction, so sideslip will not break a rudder off. It is also safe to then defect fully in the other direction if the rudder is first momentarily allowed to 'settle'. The issue was REPEATED RUDDER REVERSALS without letting the rudder 'settle'. That is idiocy. Now...

                      I'd say that "pilot idiocy" is way an over-simplification and a tad unfair. Not that there was not some of that, but there was much more than that.
                      When I say 'pilot idiocy', I am not attacking pilots. I'm attacking the system that allows pilots into the cockpit with an idiot-level understanding of rudder. We are all idiots until we learn something. I use the word 'idiocy' because it goes well beyond 'error'. The findings of the AA587 investigation were particularly chilling to me (as they were with AF447) because I had not thought it possible for airline pilots to be so clueless on basic airmanship and type-specific procedure for upset recovery. In both cases, 'pilot idiocy' took a perfectly good airplane and, through great idiotic effort (AA587 on rudder use, AF447 on stall awareness and recovery), killed everyone on board.

                      I think, due to a corrupt level of commercial interest, EASA has its hands tied bureaucratically with respect to costly reform efforts and thus it is taking the operator 'idiot-proofing' path instead. That is my interpretation of this AD. And, while I don't mind the added protection this will provide, I think it is the wrong path to be on.

                      And I don't believe for a minute that similar rudder reversals on Boeing widebodies are structurally safe. Meanwhile, because of this micro-management focus on a much larger issue, nothing is being done about that.

                      Comment


                      • #12
                        Originally posted by Evan View Post
                        And—yes—apparently nothing much had been done about this lack of understanding on the use of rudder on large transport aircraft.
                        I disagree. After the findings regarding this accident airlines at great (I can't say all of them) included syllabus about how you can exceed the aerodynamic limit loads even below Va, including by using the rudder. They also modified the syllabus of their ipset recovery training saying that aileron is the source of roll control and rudder should be used just as necessary to keep a coordinated flight, except in the high-pitch slow-speed condition that you need to roll the plane, if roll control is ineffective you can use a bit of rudder with caution just to initiate the roll.

                        However, PIO can be avoided with proper training.
                        Anything possibly doable can be done with proper training. Juggling, overturn turning a-la rally, barrel rolls in a 707...

                        PIO is an unstable mode of motion (when you take the human typical response into account into the system), but a human with enough training and practice can learn to make control inputs that are proportional to the rate rather than to the displacement. But it is not so easy and it is very different from how the pilot handles the controls normally. Of course, you can avoid PIO in the first place just by keeping your limbs off the controls (the PIO doesn't work without the P), but that's not the natural response upon an initial upset.

                        Here's where you lose me. Airbus designs MEET the requirements set out by the FARs.
                        Yes they do.

                        If those requirements are not adequate,...
                        And they aren't.

                        it's the FARs that needs to be addressed.
                        Yes it does.

                        Secondly, Airbus rudders ARE completely safe when used to the mechanical stop (or blowback limit) in one direction, so sideslip will not break a rudder off. It is also safe to then defect fully in the other direction if the rudder is first momentarily allowed to 'settle'.
                        Sure? That's beyond the requirement.

                        The issue was REPEATED RUDDER REVERSALS without letting the rudder 'settle'. That is idiocy.
                        So apply an inch of right rudder and one pound beyond breaking friction in reaction to a left yaw is idiocy? Did you note that the FAR doesn't have any requirement regarding the fin and rudder withstanding any anti-yaw inputs? So id an engine fails and the plane yaws, what are you supposed to do? Center the rudder that is already centered? I see some idiocy in the requirements too.

                        I am not neglecting the ridiculous reaction of the pilot here. That was a fundamental part of the accident. But, again, there is more to the story.

                        When I say 'pilot idiocy', I am not attacking pilots. I'm attacking the system that allows pilots into the cockpit with an idiot-level understanding of rudder. We are all idiots until we learn something. I use the word 'idiocy' because it goes well beyond 'error'. The findings of the AA587 investigation were particularly chilling to me (as they were with AF447) because I had not thought it possible for airline pilots to be so clueless on basic airmanship and type-specific procedure for upset recovery. In both cases, 'pilot idiocy' took a perfectly good airplane and, through great idiotic effort (AA587 on rudder use, AF447 on stall awareness and recovery), killed everyone on board.

                        I think, due to a corrupt level of commercial interest, EASA has its hands tied bureaucratically with respect to costly reform efforts and thus it is taking the operator 'idiot-proofing' path instead. That is my interpretation of this AD. And, while I don't mind the added protection this will provide, I think it is the wrong path to be on.

                        And I don't believe for a minute that similar rudder reversals on Boeing widebodies are structurally safe. Meanwhile, because of this micro-management focus on a much larger issue, nothing is being done about that.
                        For me the two are not comparable. One pilot was applying right rudder in reaction to left yaw and left rudder in reaction to right yaw. Yes, he did it too aggressively, repeatedly, and in phase with the motion so in fact he was reacting to his self-induced yaw (something that of course he didn't realize). And yes, no rudder at all would have been perfectly ok to manage the turbulence encounter. But applying some control inputs to correct for a turbulence disturbance (like a bit of right rudder to correct a bit of left yaw) is perfectly legal and reasonable. A little bit of rudder being equal to full rudder deflection (by design) was also a non-negligible part of the story. What this pilot attempted to do was reasonable. The problem is that he screwed the control inputs so he worsened the situation instead of improving it. But the intention was legit.

                        The other pilot, however, reacted with a stall-warning-activating, 1.5G, 15 deg nose up, 7000 fpm, 2500ft climb to what basically an autopilot self-disengaging. And that's even before the plane stalled and the pilot reacted to that with a sustained Ï was pulling up all the time" all the way to the ocean. Now this makes no sense.

                        --- 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


                        • #13
                          Originally posted by Gabriel View Post
                          I disagree. After the findings regarding this accident airlines at great (I can't say all of them) included syllabus about how you can exceed the aerodynamic limit loads even below Va, including by using the rudder. They also modified the syllabus of their ipset recovery training saying that aileron is the source of roll control and rudder should be used just as necessary to keep a coordinated flight, except in the high-pitch slow-speed condition that you need to roll the plane, if roll control is ineffective you can use a bit of rudder with caution just to initiate the roll.
                          I just hope this being properly impressed and also that upset training is being done in type-correct sims. To a pilot who, let's say, thinks what he learned on his 172 basic flights skills training is universal to large aircraft, the rudder is a dangerous flight control.

                          Anything possibly doable can be done with proper training. Juggling, overturn turning a-la rally, barrel rolls in a 707...

                          PIO is an unstable mode of motion (when you take the human typical response into account into the system), but a human with enough training and practice can learn to make control inputs that are proportional to the rate rather than to the displacement. But it is not so easy and it is very different from how the pilot handles the controls normally. Of course, you can avoid PIO in the first place just by keeping your limbs off the controls (the PIO doesn't work without the P), but that's not the natural response upon an initial upset.
                          You can eliminate PIO in this case by impressing upon pilots the role of the rudder and how you NEVER do rapid reversals. This must be instinctively taboo. No reversals, no PIO.

                          Sure? That's beyond the requirement.
                          Yes. Read the report.

                          So apply an inch of right rudder and one pound beyond breaking friction in reaction to a left yaw is idiocy? Did you note that the FAR doesn't have any requirement regarding the fin and rudder withstanding any anti-yaw inputs? So id an engine fails and the plane yaws, what are you supposed to do? Center the rudder that is already centered? I see some idiocy in the requirements too.
                          Again, Gabriel, a full defection in one direction is not a structural problem.

                          I am not neglecting the ridiculous reaction of the pilot here. That was a fundamental part of the accident. But, again, there is more to the story.
                          I've read the story in the report. Pilots were not being properly trained on the role and use of rudder on large transport aircraft. They were being told incorrect things about wake turbulence recovery. They were training in the wrong sims. The issue of rudder sensitivity was addressed but it really isn't the issue because the issue is not how much rudder pressure is applied, it is the nature of the application. My comparison to AF447 was only in the revelation that line pilots at major flag-carrier airlines were not being taught how to recover from upset. It's not a matter of degree, it's a matter of negligence.

                          Comment


                          • #14
                            Originally posted by Gabriel View Post
                            Evan,

                            Have you ever thought that applying right rudder might be, for some pilots, a natural reaction upon an unwanted and uncommanded (or so they think) left yaw/sideslip?
                            No, using the rudder to control yaw/sideslip is more of that fundamental cowboy BS that has no business in commercial aviation (even though it is used on almost every landing AND taught for upset recovery).

                            ...and I still find the amount of pedal travel (minimal) and force (not all that impressive) required to flap the thing far enough right and left to bust it off to be troublesome (you know, more of that human factors thing)
                            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                            Comment


                            • #15
                              Originally posted by 3WE View Post
                              No, using the rudder to control yaw/sideslip is more of that fundamental cowboy BS that has no business in commercial aviation (even though it is used on almost every landing AND taught for upset recovery).
                              And yet...

                              Originally posted by Evan
                              The rudder on a large transport aircraft is there for turn coordination (which often requires no pilot inputs), moderate sideslip manuevers and thrust assymetry. It's not a primary flight control for roll excursions. And it certainly is not there to be wagged around by improvising pilots.
                              But you're just here to troll. I keep forgetting that.

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