14 May 1997 New hearing at the trial for Senna's death. Liutenant Andrea Hallgas (military aviation expert on materials) and prof. Giampaolo Cammarota (lecturer in metallurgy at the University of Bologna) said that the steering column broke because it was badly designed. According to the Williams experts the steering column broke only after hitting the wall, because the torsion required to break it was only reached at the time of the impact, according to the telemetry.
Hallgas and Cammarota disagreed on what caused the steering column to break. According to Hallgas, the column broke where it was joined because the difference in section between the two joined pieces caused the stress to concentrate there, not because it had been badly welded. According to Hallgas the resistence to stress of the column was reduced to one third at tht point of joint and a crack corresponding to 70% of the circumpherence (or 35-40% of the section) was present before the column broke.
Cammarota disagreed with Hallgas on the size of the initial crack (more than 60% of the section according to him) which lead to the breakage and said that the quality of the welding was one of the causes of the breakage of the column.
The Williams experts (Vitali and Suppo) agree with Hallgas and disagree with Cammarota, saying that Hallgas used magnification up to 900 times, while Cammarota only used magnification up to 70 times. According to them the crack in the column was about 21% of the section and certainly no more than 40%.
On 28 May new images from Senna's in-car camera, clearer than those already seen, will be shown.

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