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Flt 587-Airbus vs American Airlines
http://www.nytimes.com/2004/03/21/nyregion/21plane.html is a report of
the maneuvering by both Airbus and American Airlines to get in their 2 cents, pilot training vs inadequate design, in the crash of AA Flt 587 over Queens. Apparently the tail came off because of a violent yaw type of pilot induced oscillation. The range of rudder control available to the pilot seems grossly inadequate. AA may have contributed to the problem by failing to reflect the design flaw in their training, however their real failure might be not grounding the planes for suicidal instability. Pilots of the F86D had to accept working around a low altitude-high speed pilot induced oscillation. In that case the oscillations were in pitch. I could accept such on a military fighter plane, but such an accident waiting to happen in a commercial airliner seems unconscionable. John Bailey http://home.rochester.rr.com/jbxroads/mailto.html |
#2
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"John Bailey" wrote in message ... http://www.nytimes.com/2004/03/21/nyregion/21plane.html is a report of the maneuvering by both Airbus and American Airlines to get in their 2 cents, pilot training vs inadequate design, in the crash of AA Flt 587 over Queens. Apparently the tail came off because of a violent yaw type of pilot induced oscillation. The range of rudder control available to the pilot seems grossly inadequate. The pilot's excess command authority over the rudder control system is why the structure delaminated. AA may have contributed to the problem by failing to reflect the design flaw in their training, however their real failure might be not grounding the planes for suicidal instability. I'll leave this the Schmidt to answer. Pilots of the F86D had to accept working around a low altitude-high speed pilot induced oscillation. In that case the oscillations were in pitch. I could accept such on a military fighter plane, but such an accident waiting to happen in a commercial airliner seems unconscionable. The airplane experianced a rudder stall (rudder reversal) due to turbulent air flow; which was probably a direct result of ATC loss of seperation. There is a USAir flight 427 suspected of having crashed for the same reason. It is quite possible that training pilots to use excessive rudder and operator panic are the cause of these crashes; excepting the abnormal operating conditions. |
#3
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"John Bailey" wrote http://www.nytimes.com/2004/03/21/nyregion/21plane.html is a report of the maneuvering by both Airbus and American Airlines to get in their 2 cents, pilot training vs inadequate design, in the crash of AA Flt 587 over Queens. Apparently the tail came off because of a violent yaw type of pilot induced oscillation. The range of rudder control available to the pilot seems grossly inadequate. AA may have contributed to the problem by failing to reflect the design flaw in their training, however their real failure might be not grounding the planes for suicidal instability. Pilots of the F86D had to accept working around a low altitude-high speed pilot induced oscillation. In that case the oscillations were in pitch. I could accept such on a military fighter plane, but such an accident waiting to happen in a commercial airliner seems unconscionable. My impression from reading the AvWeek reports is that this problem isn't unique to A300s nor to Airbus products. The fin can be overloaded in most transports if opposite rudder is commanded while a significant yaw has occurred. I'm not a pilot but AvWeek claimed that standard recovery training for transport pilots could lead to this condition. |
#4
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After an exhausting session with Victoria's Secret Police, "Paul F
Austin" confessed the following: My impression from reading the AvWeek reports is that this problem isn't unique to A300s nor to Airbus products. The fin can be overloaded in most transports if opposite rudder is commanded while a significant yaw has occurred. I'm not a pilot but AvWeek claimed that standard recovery training for transport pilots could lead to this condition. You are correct, I fly the 757 and we've recently had some expanded warning verbiage added to our flight manual about excessive rudder inputs during an engine failure. Pretty soon after that AA crash we were cautioned about excessive rudder inputs. Why is rudder input mandatory during an engine failure vice simply using ailerons? Quick example, a United 747-400 lost an engine on takeoff from SFO a couple years back. The jet was full/heavy, the FO (guy in the right seat) was making the takeoff. During intial climbout, the FO used full aileron/yoke to maintain wings level while trying to climb straight out. The only problem was the drag caused by the deployed spoilers (for roll) on the side with two good motors. [picture aileron into the two good engines trying to "lift" the wing with only one motor to turn into the good side]. This was not the approved solution for controlling a 747 on takeoff with an engine failure. As a result the drag severely degraded the climb capability and there was a ridge line in front of the jet. Two guys sitting in jumpseats finally had enough of the FO's hamfisted technique and started insisting he use rudder to control the yaw and not aileron. The FO listened..."Oh yeah, ****, f*ck me..." and they cleared the rapidly rising terrain by mere feet. So that is why rudder input is critical, minimize yaw and drag to provide climb performance. And as you alluded to, blind rapid full rudder inputs can simply over-G the airframe. The technique we are taught during an engine failure is to climb straight ahead (airspace and terrain permitting), engine failure during the takeoff roll are pretty painless if you simply blend in enough rudder to keep on centerline as you accelerate then shift to instruments once airborne. Engine failure during climbout while in a turn can be disorienting with the greater yawing and rolling tendencies due to higher speeds and power settings...obviously greater care must be taken by the pilot flying the jet. Juvat |
#5
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"Robey Price" wrote After an exhausting session with Victoria's Secret Police, "Paul F Austin" confessed the following: My impression from reading the AvWeek reports is that this problem isn't unique to A300s nor to Airbus products. The fin can be overloaded in most transports if opposite rudder is commanded while a significant yaw has occurred. I'm not a pilot but AvWeek claimed that standard recovery training for transport pilots could lead to this condition. You are correct, I fly the 757 and we've recently had some expanded warning verbiage added to our flight manual about excessive rudder inputs during an engine failure. Pretty soon after that AA crash we were cautioned about excessive rudder inputs. Why is rudder input mandatory during an engine failure vice simply using ailerons? Quick example, a United 747-400 lost an engine on takeoff from SFO a couple years back. The jet was full/heavy, the FO (guy in the right seat) was making the takeoff. During intial climbout, the FO used full aileron/yoke to maintain wings level while trying to climb straight out. The only problem was the drag caused by the deployed spoilers (for roll) on the side with two good motors. [picture aileron into the two good engines trying to "lift" the wing with only one motor to turn into the good side]. This was not the approved solution for controlling a 747 on takeoff with an engine failure. As a result the drag severely degraded the climb capability and there was a ridge line in front of the jet. Two guys sitting in jumpseats finally had enough of the FO's hamfisted technique and started insisting he use rudder to control the yaw and not aileron. The FO listened..."Oh yeah, ****, f*ck me..." and they cleared the rapidly rising terrain by mere feet. So that is why rudder input is critical, minimize yaw and drag to provide climb performance. And as you alluded to, blind rapid full rudder inputs can simply over-G the airframe. The technique we are taught during an engine failure is to climb straight ahead (airspace and terrain permitting), engine failure during the takeoff roll are pretty painless if you simply blend in enough rudder to keep on centerline as you accelerate then shift to instruments once airborne. Engine failure during climbout while in a turn can be disorienting with the greater yawing and rolling tendencies due to higher speeds and power settings...obviously greater care must be taken by the pilot flying the jet. Thanks for the information. I am somewhat amazed that the FAA doesn't require load analysis of the fin under yaw/extreme opposite rudder but (again according to AvWeek), it does not. |
#6
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In article ,
"Paul F Austin" wrote: "Robey Price" wrote After an exhausting session with Victoria's Secret Police, "Paul F Austin" confessed the following: My impression from reading the AvWeek reports is that this problem isn't unique to A300s nor to Airbus products. The fin can be overloaded in most transports if opposite rudder is commanded while a significant yaw has occurred. I'm not a pilot but AvWeek claimed that standard recovery training for transport pilots could lead to this condition. You are correct, I fly the 757 and we've recently had some expanded warning verbiage added to our flight manual about excessive rudder inputs during an engine failure. Pretty soon after that AA crash we were cautioned about excessive rudder inputs. Why is rudder input mandatory during an engine failure vice simply using ailerons? Quick example, a United 747-400 lost an engine on takeoff from SFO a couple years back. The jet was full/heavy, the FO (guy in the right seat) was making the takeoff. During intial climbout, the FO used full aileron/yoke to maintain wings level while trying to climb straight out. The only problem was the drag caused by the deployed spoilers (for roll) on the side with two good motors. [picture aileron into the two good engines trying to "lift" the wing with only one motor to turn into the good side]. This was not the approved solution for controlling a 747 on takeoff with an engine failure. As a result the drag severely degraded the climb capability and there was a ridge line in front of the jet. Two guys sitting in jumpseats finally had enough of the FO's hamfisted technique and started insisting he use rudder to control the yaw and not aileron. The FO listened..."Oh yeah, ****, f*ck me..." and they cleared the rapidly rising terrain by mere feet. So that is why rudder input is critical, minimize yaw and drag to provide climb performance. And as you alluded to, blind rapid full rudder inputs can simply over-G the airframe. The technique we are taught during an engine failure is to climb straight ahead (airspace and terrain permitting), engine failure during the takeoff roll are pretty painless if you simply blend in enough rudder to keep on centerline as you accelerate then shift to instruments once airborne. Engine failure during climbout while in a turn can be disorienting with the greater yawing and rolling tendencies due to higher speeds and power settings...obviously greater care must be taken by the pilot flying the jet. Thanks for the information. I am somewhat amazed that the FAA doesn't require load analysis of the fin under yaw/extreme opposite rudder but (again according to AvWeek), it does not. Political and un-Diplomatic pressure from the foreign states heavily invested in the sucess of Airbus. -- Ron |
#8
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After an exhausting session with Victoria's Secret Police, John
Bailey confessed the following: Remarks in response to the original post assume the actual failu the rudder failing catastrophically, was due to the pilot responding in an excessive way to a situation in which yaw needed to be controlled. These resonses do not mention the fact that the yaw needing to be controlled AND the excessive response came from a characteristic of the plane itself. Good point. In addition, rudder application does not move the plane instantly, and the delay might encourage a pilot to keep applying the rudder until the aircraft moved further than the pilot intended, according to Mr. Hess's analysis. The natural reaction would then be to apply the rudder in the opposite direction. (end quote) I've witnessed yaw PIO during V(one) cuts in the MD-80 and 757 simulator, it can happen with any jet IMO in a high pucker factor situation...was never a problem in the F-16 8-) Pilot induced oscillation is the result of a failure of the controls design to take into account the inherent lag of the human control response. Which is addressed in the F-16 with Standby Gains when the gear is down or the refueling door is open. Would have been nice for the F-4 when refueling at a heavy weight and high altitude (above about FL270). Apparently the most notorious case occured when the squadron commander at Selfridge AFB, lead a flyby formation, reaching levels of oscillation that had his wingtips generating vortex fog Ya know you don't have to be doing anything special to generate visible wingtip vortices. See them all the time in high relative humid conditions from jets stabilized on final approach...but I get your point. The worst case I've heard of was an airshow flyby of RoKAF F-4s. Number 3 trying to be perfect as Sq CO Lead approaches the sight line at a very high speed (running late IIRC) gets into vicious PIO and finally "freezes" the stick aft as his jet zooms out of formation for an unscheduled missing man demo (much better than a fireball sliding down the runway). Juvat |
#9
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"John Bailey" wrote in message ... Here is the key quote: (quote) But the author of the study, Ronald A. Hess of the University of California, said that the design of the rudder was conducive to such oscillations. One problem, he found, was that on the A-300, the amount of force needed to start moving the rudder was relatively high, and the total range of motion allowed at that speed was only a little over an inch, making it very difficult to apply any amount of rudder less than its full extension. In addition, rudder application does not move the plane instantly, and the delay might encourage a pilot to keep applying the rudder until the aircraft moved further than the pilot intended, according to Mr. Hess's analysis. The natural reaction would then be to apply the rudder in the opposite direction. (end quote) More likely Hess is full of **** and should look further into the circumstances of the crash. |
#10
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Political and un-Diplomatic pressure from the foreign states heavily invested in the sucess of Airbus. The same for Boeing 737 tail problem... resolved for the entire fleet only in ....2012.... |
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