Air France Overhauls Air Speed Sensors

Workers unload debris, belonging to crashed Air France flight 447, from the Brazilian Navy's Constitution Frigate in the port of Recife, northeast of Brazil, June 14, 2009. (AP Photo/Eraldo Peres)
AP Photo/Eraldo Peres
Air France has replaced the air speed sensors on its entire fleet of Airbus A330 and A340 long-haul aircraft, according to a pilots' union official

Investigators looking into the crash of Air France Flight 447 last month have so far focused on the possibility that external speed monitors - called Pitot tubes - iced over and gave false readings to the plane's computers.

Air France pledged to replace older models of the Pitots on its A330 and A340 planes by the end of this month, after pilots complained that the change, which began in May, was not proceeding quickly enough.

Eric Derivry, a spokesman for the SNPL pilot's union, said Monday the entire fleet is now equipped with the newer sensors.

Flight 447 was carrying 228 people from Rio de Janeiro to Paris on May 31 when it ran into fierce thunderstorms. Brazilian authorities say they have retrieved 44 bodies. Another six have been pulled from the Atlantic by French ships.

Over the weekend, it was revealed that a burst of last-minute automatic messages sent by the plane includes one about a problem with a rudder safety device. But that does not explain what sent the jet plunging into the Atlantic Ocean, an aviation expert says.

The industry official, who has knowledge of the Air France investigation, told The Associated Press that a transcript of the messages posted on the Web site EuroCockpit is authentic but inconclusive.

One of the 24 automatic messages sent from the plane minutes before it disappeared 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 fished out of the water by Brazilian searchers.

"There is a lot of information, but not many clues," the official said, speaking on condition of anonymity because he is not authorized to discuss the matter.

The official said jets like the Airbus A330 automatically send such maintenance messages about once a minute during a plane's flight. They are used by the ground crew to make repairs once a plane lands.

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 may 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.

"The message tells us that the rudder limiter was inoperative," said Jack Casey, an aviation safety consultant in Washington, D.C. "It does not give you any reason why it is not working or what caused it, or what came afterward."

Unless the plane's flight data and cockpit voice recorders - the black boxes - are found, the exact cause of the accident may never be known.

A French nuclear submarine is scouring the search area in the hopes of hearing audio pings from the black boxes' emergency beacons and the first of two U.S. locator listening devices is scheduled to arrive Sunday.

But the search area includes a wide grid and some of the deepest waters of the Atlantic - and searchers have only two more weeks before the signals from the black boxes begin to fade.

So far, there is no evidence of an explosion or terrorist act, just clues that point to systemic failures on the plane. Experts have said the evidence uncovered so far points to at least a partial midair breakup of the Airbus A330.

Military ships and planes had to suspend the search for bodies and debris Saturday afternoon because of bad weather. No more bodies were recovered, but a "medium-size" piece of plane debris was discovered Saturday, according to Brazilian air force Gen. Ramon Cardoso.

Coroners also said dental records of the victims and DNA samples from relatives will be necessary to confirm the identities the 16 bodies examined thus far.