FYI....
American argues that Airbus knew that the A300-600 and A310 were prone to rudder overcontrolling from three or four prior incidents dating back to at least 1991 that were presented in NTSB testimony (AW&ST Nov. 25, 2002, p. 44).
Calculations showed that these rudder motions overloaded the fin beyond limit load in several cases, and beyond ultimate load (1.5 times limit load) in at least two instances--a point at which the fin might be expected to break off. One of those ultimate load violations was on American's Flight 903 in May 1997 and the other was on an Interflug A310 in 1991. Other cases include an Air France Flight 825 incident in December 1999 on an A310 where limit load was exceeded.
A key document, American says, is a June 19, 1997, Airbus internal memorandum stating that in Flight 903's "rear fuselage, fin and empennage the ultimate design loads may have been exceeded." This knowledge did not come to the NTSB or American until the document was revealed after the Flight 587 accident more than four years later.
"With Interflug, you could say it was a one-off," says Bruce Hicks, an American spokesman. "But with 903 you have to connect the dots, and Air France 825 clinched it."
American claims Airbus knew of overloads but did not inform operators or authorities in sufficiently specific language that would catch their attention, nor did the manufacturer convey data about the series of rudder overcontrol incidents on the A300-600 and A310.
An independent study requested as part of the NTSB Flight 587 investigation showed that at higher speeds, where pilots rarely use the pedals, the rudder of these two types is 3.2-10 times more sensitive (in terms of deflection per incremental force) than other transports, with a breakout force several times larger than the incremental force for full deflection (see graph, p. 45). An NTSB poll of Boeing, Douglas and Airbus histories showed that no other type had this history of fin overload.
