A non-destructive inspection apparatus for inspecting a structure, comprising: a first probe configured for traveling over a first surface of the structure under inspection, the first probe comprising at least one inspection sensor for inspecting the structure as the first probe is moved over the first surface of the structure and at least one magnetic coupling device; and a second probe configured for traveling over a second surface of the structure and magnetically coupled to the first probe, the second probe comprising and at least one magnetic coupling device, wherein the probes cooperate by the magnetic attraction between corresponding magnetic coupling devices to correspondingly move the magnetically coupled probes over the respective surfaces of the structure; characterised in that the first probe is further configured to span a cross-section of the structure that protrudes from the first surface of the structure; characterised in that the first probe includes three separate transducer holders (202, 204, 206) including two side transducer holders (202, 204) and one central transducer holder which each include magnetic coupling devices and recesses (138, 139) for inspection sensors; wherein the second probe includes side portions (93, 94) connected by hinges that permit the side portions (93, 94) of the second inspection probe to rotate to match corresponding angles of sides of the structure that protrudes from the structure under inspection; such that the magnetic attraction between the magnetic coupling devices of the first and second probes (200, 90) permits re-orientation of the two side transducer holders (202, 204) relative to the central transducer holder to match the corresponding angles of the structure that protrudes from the structure under inspection. a first probe configured for traveling over a first surface of the structure under inspection, the first probe comprising at least one inspection sensor for inspecting the structure as the first probe is moved over the first surface of the structure and at least one magnetic coupling device; and a second probe configured for traveling over a second surface of the structure and magnetically coupled to the first probe, the second probe comprising and at least one magnetic coupling device, wherein the probes cooperate by the magnetic attraction between corresponding magnetic coupling devices to correspondingly move the magnetically coupled probes over the respective surfaces of the structure; characterised in that the first probe is further configured to span a cross-section of the structure that protrudes from the first surface of the structure; characterised in that the first probe includes three separate transducer holders (202, 204, 206) including two side transducer holders (202, 204) and one central transducer holder which each include magnetic coupling devices and recesses (138, 139) for inspection sensors; wherein the second probe includes side portions (93, 94) connected by hinges that permit the side portions (93, 94) of the second inspection probe to rotate to match corresponding angles of sides of the structure that protrudes from the structure under inspection; such that the magnetic attraction between the magnetic coupling devices of the first and second probes (200, 90) permits re-orientation of the two side transducer holders (202, 204) relative to the central transducer holder to match the corresponding angles of the structure that protrudes from the structure under inspection.