RIO DE JANEIRO - A burst of automatic messages sent by Air France Flight 447 offers few concrete clues into what made the plane crash into the Atlantic en route to Paris two weeks ago, an aviation expert said yesterday.
The industry official, who has knowledge of the Air France investigation, said that a transcript of the messages posted on the Web site EuroCockpit was authentic, but inconclusive.
"There is a lot of information, but not many clues," the official said, speaking on condition of anonymity because he was not authorized to discuss the matter.
The official said jets such as the Airbus A330 that crashed send such maintenance messages automatically about once a minute during a plane's flight. They are used by the ground crew to make repairs once a plane lands.
Martine del Bono, spokeswoman for the French investigative agency BEA, which is in charge of the crash probe, and Airbus spokesman Stefan Schaffrath declined to comment on the transcript.
One of the 24 automatic messages sent from the plane minutes before it disappeared May 31 with 228 on board points to a problem in the "rudder limiter," a mechanism that limits how far the plane's rudder can move.
The nearly intact vertical stabilizer - which includes the rudder - was recovered from the ocean last week.
If the rudder were to move too far while traveling fast, it could shear off and take the vertical stabilizer with it, which some experts theorize might have happened based on the relatively limited damage to the stabilizer.
The industry official, however, said the error message pertaining to the rudder limiter did not indicate it malfunctioned, but rather that it had locked itself in place because of conflicting speed readings.
Investigators have focused on the possibility that external speed monitors - called Pitot tubes - iced over and gave false readings to the plane's computers.
"The message tells us that the rudder limiter was inoperative," Jack Casey, an aviation safety consultant in Washington, said when the existence of the automatic messages was first divulged. "It tells us that for some reason it was no longer functioning. That is all the message means."
"It does not give you any reason why it is not working, or what caused it, or what came afterward," Casey said.
Unless the plane's flight data and cockpit voice recorders - the so-called black boxes - are found, the exact cause of the accident may never be known.