FAA orders Airbus speed sensors replaced

ByABC News
September 4, 2009, 2:15 AM

WASHINGTON -- U.S. operators of wide-body Airbus jets must replace most of their speed sensors after an investigation into the crash of an Air France jet in June found that the sensors can fail amid bad weather at high altitudes.

The Federal Aviation Administration, following the lead of European aviation regulators, said Thursday that it had reviewed "numerous" reports of speed-sensor failures on the long-range A330 and A340 jets.

The failed speed sensors can create a critical "unsafe condition," the FAA said. Airlines have 120 days from this coming Tuesday to install the new sensors. European regulators have issued a similar order.

Air France Flight 447, an Airbus A330 carrying 228 people, disappeared June 1 after leaving Rio de Janeiro for Paris. All on board were killed. Investigators have not determined what happened, but data messages transmitted from the jet indicated that its complex flight-control computers began degrading after the speed sensors malfunctioned, according to the French Bureau d'Enquetes et d'Analyses.

Pitot tubes calculate a jet's speed by sensing changes in air pressure. The devices have a roughly 4-inch-long tube that faces forward. As speed increases, air is rammed into the tube and pressure increases.

Airliners have at least three separate Pitot tubes for redundancy. In the rare event that they fail, pilots are taught to fly level and leave engines at normal settings. But in several cases pilots have become so confused when the sensors failed that they crashed.

The FAA said speed-sensor failure on the highly automated Airbus jets could cause the autothrust and autopilot functions to switch off, forcing pilots to fly manually. "This condition, if not corrected, could result in reduced control of the airplane," the FAA said.

Delta Air Lines and US Airways operate a total of 43 of the jets. Delta has begun the replacement and expects to finish soon on its fleet of 32 A330s, said spokeswoman Ashley Black. US Airways has finished the installation, said spokeswoman Valerie Wunder.