The FADEC on the -80E is located on the fan casing at the 2 o'clock position as you would be looking at the fan from the front of the engine
So this is why the fan casings would be of interest if they cannot recover any information off the fdr?
Nobody else has picked up on my comment about where the THS is..For a mission such as this the minimum fuel in the tail would have been at least 2500kg at TO with the trim adding up to another 2000 kg for the cruise.If 4500 kg of fuel was trapped inside ther trim tank it would have made the THS relatively buoyant but if it leaked out I would have thought it would have made a visible slick on the surface...but what do I know!!!