David Learmount/LONDON
The tyre blow-out which brought down the Air France Concorde on 25 July occurred 1,600m (4,900ft) from the start of the aircraft's take-off run at Paris Charles de Gaulle airport, according to the French Bureau Enquêtes Accidents (BEA) preliminary report.
French and UK accident investigators recommend that: "Concorde's airworthiness certificates should be suspended until such a time as appropriate measures have been put in place to guarantee a satisfactory level of safety as regards the risk associated with tyre blow-outs." These are judged as "not an improbable event on Concorde", the report says.
The crew called V1 (take-off decision speed) at 270km/h (150kt), 32s after brake release and 1,200m from the start of the take-off run. It was at 1,600m that debris from the tyre and aircraft were found, as well as traces of soot indicating that ignition of the fuel-fed underwing fire took place almost immediately after the tyre burst.
The debris included pieces of the forward right hand tyre on the port main gear bogey, pieces of the wheels' water-deflector, and part of a fuel tank. There were no parts from the engines or wheel rims, says the report, but a 430mm (17in)-long piece of metal was found. It is possible that the metal section caused the "significant gash" in the tyre and caused its failure.
Shortly before rotation the control tower told the Concorde crew: "You have flames behind you." The report confirms that the fire did not come from the engines. At this point, traces on the runway indicate that the aircraft began to slew left, which the crew countered with rudder. A moment later the flight engineer said: "Failure No 2 engine," and 4s later: "cut No 2 engine." The flight data recorder reveals that during rotation, No 2 engine lost power, was shut down, and engine No 1 lost power momentarily. Then the gear failed to retract. From the moment of take-off the aircraft did not accelerate beyond 200kt, and its height as recorded by the radio altimeter never exceeded 200ft. Then engine No 1 ran down, the left wing dipped and the aircraft crashed.
The BEA and the UK Air Accident Investigation Branch agree that the crew could not have known about the extent of the blaze below the left wing. The cause of ignition of the escaping fuel is still undetermined.
Source: Flight International
