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Originally Posted by Brian Carlton
I rather like to listen to your $.02 Dave, and have to hijack this thread to seek you opinion on the A300-600R. With the Airbus philosophy of letting the computer keep the control surfaces within operating limits, and not allow the pilot to override, how was it possible for the pilot of the A300-600R to exceed the design limits for the tail by more than 50%.
It appears that Airbus does not know the limit for the tail, or, they have failed to properly program the flight control system. 
Maybe I'm asking the wrong question. Do you believe that the pilot exceeded the design load for the tail by more than 50%? |
A couple of things about the A300-600R this aircraft is not a fly by wire, ?The rudders are hydraulicly controlled.
Designed in all transport aircraft is a rudder limiter that restricts the amount of actual deflection based upon aircraft speed. As the speed increases the amount of rudder movement decreases. This is designed to prevent over stressing the rudder as well as over controlling the yaw axis. As I said ALL modern airliners have this.
Here are the differneces that American and our union were trying to bring to the forefront of the investigation.
The amount of yaw produced even with the limiter applied is greater on the A300 then all other transport aircraft. 1.5 inches of rudder travel produces the full rudder movement, It take about twice as much on the other aircraft. so the aircraft is highly sensitive in yaw.
Second, all the training done that I and 95% of the pilots out there, mentions nothing about rudder oscilation inputs. My training is civilian thru ATP and Military C141's. I now have about 17,000 hours flying. Because of our accident it has come to the forefront, the design criteria of a transport aircraft. The rudder system is designed for a full deflection in one direction and then the other, AND THAT IS IT. If you continue this application of rudder back and forth you can exceed the design limit of the aircraft.
The wake turbulence recovery technique, which they were doing, was to possibly use rudder to help the aircraft to right itself.
The interesting part, After an incident 4 years ago in another one of our A300s Airbus looked at the stress loads and realized that maybe thru pilot training, the pilot force out there did not know of the oscilation problem. But they did not tell anyone. It would have been nice of them to relay there finding to the operators of the aircraft.
Can I over stress my aircraft, Yes in some ways. Oscilating the ailerons, no the elevator, yes or in the case of a rapid application, I can over G the aircraft which would cause the wings to seperate. But this we have been trained on. Our G limit is specified in the limits of out operating manual. And thru Air Force pilot training I have had aircraft up to 6 G's so I am familiar with different G levels on the aircraft.
Rudder use for control of the aircraft was actually taught in pilot training.
The big concern from a pilots point of view is WHY is the A300 rudder system so sensitve and why were we not informed of the oscilating problem thru my 35 years of pilot training. Of course now it is in the manuals.
One item that has been taught is manuevering speed, The concept taught is that at or below manuevering speed you cannot over stress the aircraft. The flight surface will stall before is can produce the force that will over stress the aircraft. Well a slight revision. You can overstress at manuevering speed, this idea applies only to the wings. If I pull on the control yoke at or below manuevering speed the wing will stall prior to over G-ing the aircraft. It applies to that axis only--- now.
Is it possible to over G the yaw axis in the fly by wire aircraft, The latest coming from the FAA and all manufacture is YES. I have not heard anything specific about fly by wire aircraft, but then again my training is specific to the MD80
Dave