Liftable arm assembly for use in making bore-holes

An erectable arm assembly (14) for use in a borehole, the erectable arm assembly comprising a main body (20) and an arm member (22), the arm member being able to move between a collapsed position in which the assembly can be removed from the borehole and an erected position, the erectable arm assembly being adapted to house a fluid drilling assembly comprising a fluid cutting device (16) and a flexible hose drill string such that the arm member during erection can contain at least part of the fluid drilling assembly, and when in the erected position the arm member is able to guide the fluid cutting device towards the borehole wall, the assembly further including at least one sensor for monitoring the arm member or the fluid drilling assembly.