An assembly for an aircraft including a first structure mounted to a second structure, and a power transfer assembly electrically connecting the first and second structures. The first structure is movable relative to the second structure between a retracted and an extended position. The power transfer assembly includes a housing, a spool mounted for rotation relative to the housing and biased to rotate in a first direction, and an electrical cable adapted to be wound around the spool when the spool rotates, such that movement of the first structure from its retracted to its extended position causes the cable to be unwound from the spool by rotation of the spool in a second direction opposite the first. Also, a method of electrically connecting the first and second structures. The invention may be applied to an aircraft wing to electrically connect a leading edge slat to a fixed aerofoil portion.