Tyre-bursts and the loss of wheel bolts on British Airways or Air France Concordes led to perforations in the supersonic airliner's fuel-tanks on occasions before last July's fatal aircrash outside Paris, the French Accident Investigation Office (BEA) has reported.
In its latest progress report on the investigation into the crash which killed 113 people, the BEA said that in all there had been 57 cases of Concorde tyres bursting on the runway since the aircraft entered service in 1976.
The BEA also raised a new theory about how pieces of metal flung up from the tyreburst on the doomed Air France plane could have touched off an explosion in the fuel-tank housed in the jet's left wing.
So far it had been assumed that shards of metal pierced and entered the tank's metal casing, but the latest findings suggest a shock-wave caused by the impact may have caused the tank to burst from the inside, the BEA said.
The report confirmed the widespread presumption that last July's accident, in which an Air France Concorde crashed on a hotel north of Paris, was caused by a piece of metal that had fallen from a DC-10 that was on the tarmac shortly before the Concorde took off.
The metal strip lacerated a tyre on the Concorde and set off a chain of reactions that led to an explosion in the fuel-tank, the report stated.
Delineating six previous incidents between 1979 and 1993 in which fuel-tanks had been perforated, the BEA said that five of them had been caused by burst tyres on the runway, and one when a wheel lost 10 bolts.
"In only one case was the fuel tank perforated by a section of tyre," the report stated. In the other instances, it was various other pieces that caused the damage. "None of these events caused the fuel tank to burst or catch fire," it added.
The BEA said a new theory was gaining credence concerning the manner in which shards of metal and rubber flung up from the tyre-burst caused the explosion in the Concorde's fuel-tank last July.
Initially, investigators supposed that the shards pierced the tank's casing from the outside, but "first analysis of the section of oil tank found on the runway suggest that the burst came from the inside towards the exterior," the BEA said. This would indicate that the impact of the metal pieces on the wing set off a shock-wave within the tank, the BEA said.
Last month, an Anglo-French working group said that tests on a modified Concorde could take place as early as February after fuel tanks had been reinforced.
--(AFP)
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