This Institute received via Jutta Rabe/Gregg Bemis two specimen cut from Sample No. 1 by the MPA and their preliminary opinion reads as follows:

»Direct evaluation of the fracture surface on one of the two samples was attempted by removal of corrosion product using cathodic cleaning, followed by examination via scanning electron microscopy. This proved unfruitful, since the original fracture topography was found to be almost completely obliterated by corrosion. Nevertheless, the angled geometry of both fracture surfaces, combined with subsequent metallographic observations, clearly indicated fracture by a shearing mechanism due to tensile overload.

Item 1, a small section that had been taken from the triangular sample by a transverse cut through its fracture surface, was prepared for metallographic examination. This revealed distinct evidence of deformation twinning in the plastically deformed region near the fracture surface. In ferrite steels such as the present bulkhead material this phenomenon is associated with high strain rate and/or low temperature deformation. We do not yet have the necessary data to specify a strain rate below which it would not occur in this particular steel at the approximately 45°F temperature of the Estonia tragedy. However, I believe at this point it is valid to say that an explosion was far more likely than a mechanical loading event to have produced the observed micro structural feature. This interpreta-tion is consistent with the localization of plastic strain along the fracture surface, which is a characteristic of elevated strain rates as well as the “petalled” appearance of the edge of the hole in the bulkhead. We are in the process of conducting additional tests and examinations to validate this conclusion.«

The conclusion of this preliminary examination was that “it is valid to say that an explosion was far more likely than a mechanical loading event to have produced the observed micro structural features”.
We do not know whether this Institute ever went deeper into the investigation and/or received other specimen from the area of Sample No. 1 having been closer to the explosion site, nor do we know whether the Institute ever produced a final report.

We did not submit this rather meagre result to Brian Braidwood and have only taken it up in this Report since the involvement of the Southwest Institute has been reported by the media. In any event, it is a further indication for an explosion to have occurred behind the starboard upper front bulkhead of the ESTONIA, although by far not as strong as the MPA and the DN Institute findings.