Though the ultimate reason for the Air France A330 crash in the South Atlantic will likely never be known for sure, the European Aviation Safety Agency (EASA) has recently issued an urgent Airworthiness Directive to replace certain Thales-manufactured pitot tubes on A330/A340 airplanes. A pitot tube problem is one of the possible explanations for that Air France crash.
For those who don’t know, a pitot tube is a goofy little thing that sticks out from the aircraft into the air. You can see a great example of one at left. These little guys use pressure measurement to determine airspeed. One of the theories regarding the Air France accident is that the pitot tube incorrectly measured airspeed and that triggered all kinds of problems that ultimately led to the accident.
Now, EASA is saying that any A330/A340 aircraft with the Thales pitot tubes need to be changed (and the FAA has followed as well). There are apparently two different types of Thales pitot tubes. The “AA” version must be replaced no matter what. The “BA” version is ok in one place, but the other two places must have Goodrich ones involved.
So what exactly is the problem? According to EASA:
Occurrences have been reported on the A330/A340 family aeroplanes of airspeed indication discrepancies while flying at high altitudes in inclement weather conditions.
The Thales AA pitots have “a greater susceptibility to adverse environmental conditions” than the Goodrich ones. The Thales BA pitots are better, but “it has not yet demonstrated the same level of robustness to withstand high-altitude ice crystals as the Goodrich . . . probe.”
While they say that they haven’t actually found any safety issue and that this is a precautionary measure, the fact that these all need to be replaced within 4 months certainly makes it seem somewhat rushed.
By the way, Air France had Thales pitot tubes, but they’ve already made these changes. Delta has also already made the changes to their A330s. Both US Airways and Lufthansa have always had Goodrich.