<image>As shown in the figure, in the Cartesian coordinate plane, the right triangle $$Rt\triangle ABC$$ is located in the first quadrant. The legs $$BC$$ and $$BA$$ are parallel to the $$y$$ axis and $$x$$ axis, respectively. The coordinates of point $$A$$ are $$(5,1)$$, $$BC=2$$, and $$AB=4$$.

 $$(1)$$ If the graph of the inverse proportion function $$y=\dfrac{a}{x}$$ ($$x > 0$$) passes through point $$C$$, then $$a=$$________. $$(2)$$ Find the equation of the line on which $$AC$$ lies. $$(3)$$ How many units does $$\triangle ABC$$ need to be translated to the right for point $$B$$ to fall on the hyperbola in $$(1)$$? $$(4)$$ If the graph of the inverse proportion function $$y=\dfrac{a}{x}$$ ($$x > 0$$) intersects any side of the $$\triangle ABC$$, directly write the range of values for $$a$$ ________________________________.