That theory was gleaned from the burst of automated messages about mechanical events sent during the last four minutes of the flight. Most of the messages appear to be linked to "incoherent" speed readings, which then affected other systems of the plane, Mr. Arslanian said.
But the report that one of those automated messages also indicated problems with the rudder limiter has renewed concerns first made public during the AA587 crash investigation in 2001.
At the time, a group of American Airlines pilots presented to the NTSB a 68-page dossier documenting incidences of uncommanded rudder movements in the A300 series jets.
In addition to the rudder incidents documented by American Airlines pilots prior to the 2001 crash of AA587, last year two Qantas Airlines Airbus 330s experienced uncommanded pitches nose-downward.Nine months before that, in January 2008, an Air Canada Airbus 319 also "experienced a sudden upset when it rolled uncommanded 36 degrees right and then 57 degrees left and pitched nose-down," according to a report on file at the NTSB.
http://www.csmonitor.com/2009/0617/p02s04-usgn.html:
Airbus has taken this system "a step further" than other manufacturers, according to the A330 pilot. That's because it also designed into the computer various "protection modes" that automatically move the plane's components if the aircraft is suddenly thrown off course by a powerful air current or some other natural event, or if a pilot simply makes a foolish error.
"It's designed to limit the ability of pilots or nature to put the plane in a stall or over-speed situation" that could jeopardize the plane, says the pilot, who has 22 years in military and commercial aviation and is certified to fly in four types of Airbuses and four types of Boeing planes. "However, the problem with these systems is that once they're activated, they are designed so the pilot cannot easily override them. So, if the computers have bad information because of an electronic anomaly or because of nature (say, the Pitot tubes are frozen and sending bad information), these built-in protections are activated immediately, and they can make it difficult for the pilot to control the plane."
In the Qantas mishap in October, the captain reported that he twice had trouble regaining control after the aircraft abruptly pitched nose-down.
"The captain reported that he applied back pressure on his sidestick to arrest the pitch-down movement. He said that initially this action seemed to have no effect, but then the aircraft responded to his control input and he commenced recovery to the assigned altitude," according to the report from the Australian Transport Safety Bureau. Less than three minutes later, the plane again suddenly pitched nose-down for no discernible reason, and the pilot again had trouble regaining control, the report found.
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