BY THE time the Air France Concorde had travelled 1200 metres down the runway
at Charles de Gaulle airport, it had reached the point of no return. It was
committed to take off as there was not enough runway left to stop. Nine hundred
metres further down the runway the plane took off with its port wing on fire.
Two minutes later the blazing Concorde crashed into a hotel, killing 113
people.
When investigators from the Bureau Enquêtes-Accidents, part of the
French Ministry of Transport, retraced the journey of flight AF4590, they found
debris from a burst tyre—or tyres—littering the runway along with a
piece of a fuel tank. All the debris was found between the point of no return
and take-off. And all of it came from the port side.
An initial analysis of the plane’s flight data recorder shows that engine
number 2 cut out and engine number 1 twice lost power during the plane’s short
flight. In photographs of the plane as it took off, a fire is coming from the
fuel tank in the wing between engine number 2 and the main fuselage.
Investigators say the fire was caused by “a major leak of fuel”.
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They say that the tyre debris triggered a chain of events including
structural damage and engine breakdown. Experts from France and Britain met
earlier this week to begin piecing together that chain of events. They will be
considering two main possibilities. First, a piece of debris from the
undercarriage might have pierced the fuel tank. This has happened on two earlier
occasions. In June 1979 flying debris from a burst tyre started a fuel leak in a
Concorde taking off from Washington DC. And in October 1993 a burst tyre on
take-off at Heathrow damaged a fuel tank. But on neither occasion did the tank
catch fire.
Secondly, the engine’s air intakes are poised above and behind the rear
wheels, so the engines could have sucked in debris from the tyres, causing a
partial break-up of an engine. Debris from a tyre has damaged an engine on three
separate occasions. But in each case the damage was contained. In July 1993, for
example, a burst tyre damaged the innermost engine.
Concorde’s design, with fuel tanks surrounding two engines on each wing,
makes it vulnerable to fire if the engine breaks apart. The risk was first
highlighted in a British Aerospace report in 1976. British Aerospace declined to
release this report when asked by 91av.
Albert Moussa of Massachusetts aviation fire specialist BlazeTech says engine
failures can create high-speed hot fragments of metal that are large enough to
pierce fuel tanks. “You get a whole distribution of debris—from a lot of
small pieces which are not going to do much damage, to on occasions a bigger
piece which can cause much more damage,” says Moussa.
He says that pictures of the doomed plane show that part of the flame was
white-hot—too hot for a simple fuel fire. “That suggests to me that metal
parts from the engine are burning and the engine failure was pretty severe.”
