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or better built planes puglist
and if you want a placard for stall recovery, I'm sure Air France will lead the way in placing the placard on their airbus fleet. and I'll take a band aid any day...its better than an open wound. by the way puglist one plane I flew says don't move control wheel more than half way above FL400 now certainly I know that, but there is a placard... oh maybe there should be one of those on the A300 too |
I suppose for now that PPRuNe serves as a placard, I hope :)
As far as "better planes" go, the weight of reinforcing the VS to survive such abuse would be prohibitive |
As illustrated in tdracer's post #100, and testified in the FAA's Final Rule on the matter, the 'placard' is now in the Airplane Flight Manuals of all transport category airplanes flying in the US.
The private citizen noted the proposed amendment is not retroactive, so it would not fix the problem for existing aircraft. Although the proposed amendment would not be retroactive, the FAA has worked with airplane manufacturers to amend their AFMs for all major transport category airplanes used in U.S. operations. The wording now in the limitations section of these AFMs meets the requirements of this final rule. |
Originally Posted by Pugilistic
An accelerated stall above Vp would impart a force that is above the limit load
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Originally Posted by bubbers44
If our A300 going out of control with yaw damper movements at 140 knots into MIA had happened at 250 knots would the VS had departed?
Originally Posted by Aviaton safety network narrative of AA903, May 12 1997
The flight was assigned an airspeed of 230 knots and cleared to descend from FL240 to 16,000 feet in preparation for landing at Miami. The FDR indicated that while the autopilot was engaged in the descent, the power levers moved from the mechanical autothrottle limit of 44 degrees to the manual limit of 37 degrees. As the aircraft leveled at 16,000 feet the airspeed decreased. The F/O began a right turn to enter a holding pattern and added some power, which stabilized the airspeed at 178 knots. However, the right bank and the resultant angle of attack (AOA) continued to increase, despite left aileron input by the autopilot. As the autopilot reached the maximum input of 20 degrees, bank angle increased past 50 degrees, and the AOA increased rapidly from 7 degrees to 12 degrees. At this point the stick shaker activated, the autopilot independently disconnected, the power was increased, and full left rudder was used to arrest the roll. The bank angle reached 56 degrees, and the AOA reached 13.7 degrees at 177 knots. The aircraft then pitched down, and entered a series of pitch, yaw, and roll maneuvers as the flight controls went through a period of oscillations for about 34 seconds. The maneuvers finally dampened and the crew recovered at approximately 13,000 feet. One passenger was seriously injured and one flight attendant received minor injuries during the upset. An analysis showed that the forces during the upset not only had gone above the design limit of the vertical stabilizer, they also apparently had reached the ultimate limit. In June 1997, Airbus requested that American Airlines perform another inspection of the jet to ensure it was not damaged. American inspectors, following Airbus' instructions, examined the tail fin. But they did not use methods that would have allowed them to see inside the tail fin. They saw no damage from their visual inspection, and the jet continued to fly until an ultrasound inspection of the horizontal stabilizer was done in March 2002. The inspection found two crescent-shaped cracks at one of the points where the tail fin attaches to the fuselage. The fin was replaced. PROBABLE CAUSE:"The flightcrew's failure to maintain adequate airspeed during leveloff which led to an inadvertent stall, and their subsequent failure to use proper stall recovery techniques. A factor contributing to the accident was the flightcrew's failure to properly use the autothrottle."
Originally Posted by Bubbers44
Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.
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I remember that one too but this one about 20 years ago was on final approach to MIA requiring a go around because of uncommanded rudder movements that they could not stop. I would guess the NTSB would have blamed the pilots if they had crashed as they both thought was going to happen. I will try to find the report and post it.
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A300 rudder actuator
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HN39
As a layman I would think that although the load factor at Va may exceed nlimit, the load would not exceed limit load. So if you are at a weight close to MTOW and at a speed above Va for that weight then you could in principle exceed both the 2.5g limit and the limit load. But at those conditions it is unlikely that one could pull enough 'g' to get anywhere near ultimate load (3.75g @ MTOW) if only because to get to a weight/airspeed condition where one could pull 3.75g one would have to burn off enough fuel to reduce the weight well below MTOW. |
bubbers44
Thank you for posting that report, but since it says several times that re-engaging the yaw dampers made things slightly easier, and since the problem was diagnosed as a failed autopilot yaw actuator clutch I don't see how your position re yaw damper failure as a possible cause of AA587 rudder movements can be sustained. Comment? |
If the FCC detects a disagreement between the autopilot clutch and the autopilot selection, the FCC will command the respective main valve solenoid to close, thus depressurizing that channel of the autopilot actuator. The examinations revealed two main findings: (1) the wiring to the two main valve solenoids had been cross-connected, and (2) a foreign-particle contaminant was found in the green system engagement valve solenoid. Examination of the actuator at the Lucas facility revealed that its two main valve solenoids were cross-connected so that the electrical connection for the yellow system was connected to the green system solenoid, and vice versa. In this configuration, the FCC for the green system would actually control the main valve for the yellow system, and the FCC for the yellow system would control the main valve for the green system. After the cross-connected wiring on N7082A was discovered, Airbus issued an All Operators Telex (AOT) on May 27, 1999, to all operators of Airbus A300, A310, and A300-600 airplanes. The AOT specified that a one-time inspection be conducted within 10 days to confirm proper connection of the main valve solenoids. As a result of the AOT checks, another American A300-600 (N3075A) autopilot yaw actuator (S/N 1630) was discovered with cross-connected autopilot solenoid wiring. American indicated that it had installed new solenoids on the three actuators (pitch, roll, and yaw) on this airplane and the rest of its A300 fleet between July 1997 and July 1999. At the time the new solenoids were installed, procedures did not specifically include a check to ensure that the solenoid wiring was installed properly. Both Airbus and Lucas have since developed new procedures to ensure that the autopilot actuator solenoids are properly wired. And as stated above nothing to do with yaw dampers. |
Thanks Owain,
I probably misunderstood PA's remark. |
As I said I was using the info the FO gave me after the incident. I didn't read this report until a couple of hours ago. I agree they found rudder actuator clutch problems. I am curious how that would cause uncommanded rudder deflections. Seems like the rudder would either work or not work.
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Originally Posted by flarepilot
by the way puglist
one plane I flew says don't move control wheel more than half way above FL400 now certainly I know that, but there is a placard... And, since there is apparently no placcard saying anything about a similar use of the rudder - would you consder doing the same control deflections - this time to the "stop" (physical or rudder limiter) for that same 6 or 7 repetitions. No placcard ... so ... no problem? Maybe, taking a clue from the lateral control placard, you might consider limiting your rudder inputs and reversals to only the same ½ value? |
Originally Posted by john_tullamarine
It is well understood by the engineering pilots around that there is a great problem with pilot education when it comes to what the certification animal does as contrasted with the line flight standards animal.
Fact of life and it is going to be a long while, if ever, before the typical pilot's knowledge base is lifted to the point where he/she has a basic idea of certification stuff. .. which is why this Forum is so important. We have a bunch of very well credentialled (a) line, training, check pilots (b) TPs and FTEs (c) certification, design, test engineers, aerodynamicists etc (d) many anciliary specialists in airports and a host of other disciplines The problem is that, sometimes, it can be difficult to sort the wheat from the chaff when posters are anonymous but that's a small problem overall as the more experienced folks offer comments (not always as subtle as might be desirable) which provide clues ... |
Unless you are doing 8pt hesitation rolls rarely do you need much more than 20 percent control movement in any aircraft.
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Originally Posted by Pugilistic Animus
…how did the plane fail them when they were doing a maneuver outside of certification? I think their training in wake encounter recovery failed them i feel bad for the flight crew and I don't really blame them as the copilot was simply doing what he was taught ...
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I guess we'll never know why this F/O did what he did the SECOND time he encountered a wing tip vortex on the SAME departure ... 5 or 6 seconds after the first encounter recovery ... but it certainly wasn't what he was trained to do.....
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I guess he forgot everything he did a few seconds before and since that worked so well decided to stomp on the rudders until the tail fell off on the second encounter. Then again did anybody check the rudder actuator clutch? If it happened once it could happen again. I wonder if it was the same airplane?
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The upset training we got we all knew was to use the rudder in low speed upsets on approach to maximize recovery not for 250 knot speeds. It had nothing to do with AA Airbus crash in my opinion.
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Originally Posted by bubbers44
Then again did anybody check the rudder actuator clutch? If it happened once it could happen again. I wonder if it was the same airplane?
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