RECIFE, Brazil - Search crews recovered the vertical stabilizer from the tail section of the Air France jet that went down in the Atlantic, Brazil's air force said yesterday - a key item in finding the cause of the crash.

Eight more bodies also were found, bringing the total recovered to 24 since Air France Flight 447 disappeared May 31 with 228 people on board, Air Force Col. Henry Munhoz said.

The discoveries are all helping searchers narrow their search for the Airbus jet's black boxes, perhaps investigators' best hope of learning what happened to the flight.

Brazilian military officials have refused to detail the large pieces of the plane they have found. But a video on the Brazilian air force Web site titled "Vertical Stabilizer Found" shows video of the piece - which keeps the jet's nose from swinging from side to side - being located and tethered to a ship.

The part had Air France's blue-and-red stripes, retained its triangular shape, and bore no evident burn marks.

Investigators are looking at the possibility that external speed monitors - called Pitot tubes - iced over and gave dangerously false readings to cockpit computers in a thunderstorm.

Peter Goelz, a former managing director of the National Transportation Safety Board, said the faulty airspeed readings and the fact that the vertical stabilizer was sheared from the jet could be related. But, he cautioned, it would need to be determined whether the stabilizer was torn off in flight or upon impact in the ocean.

The Airbus A330-200 has a "rudder limiter" that constricts how much the rudder can move at high speeds - if it were to move too far while traveling fast, it could shear off and take the vertical stabilizer with it, as they are attached.

The wreckage and the bodies were found roughly 400 miles northeast of the Fernando de Noronha islands off Brazil's northern coast, and about 45 miles from where the jet was last heard from as it headed from Rio de Janeiro toward Paris.

Some high-tech help is on the way for investigators - two U.S. Navy devices capable of picking up the flight recorders' emergency beacons on the ocean floor. They were expected to arrive in Brazil late yesterday.

An internal memo sent to Air France pilots yesterday and obtained by the Associated Press urged them to refuse to fly Airbus A330s and A340s unless at least two of the three Pitot sensors on each plane had been replaced. The sensors have drawn attention because of other incidents in which they iced over at high altitudes.

The memo was sent by the Alter union, which represents about 12 percent of Air France pilots. But the leader of another pilots' union, SNPL, said yesterday that Pitot troubles probably did not cause the Flight 447 disaster.

Air France said it began replacing the Pitot tubes on its Airbus A330s April 27 after an improved version became available. It said it would finish the work in the "coming weeks." The monitors had not yet been replaced on the doomed jet.

Air Lines Inc., US Airways Group Inc., and Aer Lingus Group P.L.C. all said yesterday that they were replacing the air-speed sensors on their Airbus jets, Bloomberg News reported.

Searchers must move quickly to find answers in Flight 447's cockpit voice and data recorders, because acoustic pingers on the boxes begin to fade 30 days after crashes.

While the finding of large pieces of debris - along with the bodies - has helped narrow the search, it remains a daunting task in waters up to 1.5 miles deep and an ocean floor marked by rugged mountains.