ECA decided to develop ALISTAR 3000, a multipurpose AUV for inspection and survey missions down to 3000m, in 2003. This AUV is designed to be particularly adapted to perform inspection of underwater structures such as pipes, wellheads, mooring lines, but is also capable of carrying out survey missions using typically acoustic and optical sensors. The architecture of an inspection AUV is much more complex than the one of a survey type AUV since it requires high manoeuvrability and hovering capacity. It needs a specific navigation software as well as dedicated sensors and algorithms to allow the vehicle to navigate relatively to, and close to the structure to be inspected, instead of the type of "absolute" navigation, usually used for survey AUVs and which purpose is only to a given accurate localization of the vehicle. This paper recalls the technical solution retained by ECA for the design of ALISTAR 3000 as well as illustrations of typical inspection missions carried out by this AUV. It then details the technical solutions retained for the missions (sensors used etc.) and presents the results of the AUV sea trials carried out since September 05 that includes the ones carried out in the Gulf of Mexico for a major oil company in July 06, consisting in various levels of pipe inspection down to 1400m depth

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