A pylon for supporting an aircraft turbomachine, in particular for a test bench, the pylon having a generally elongated shape along an axis and including, at a first longitudinal end, first members for fixing to a turbomachine and, at a second longitudinal end, second members for fixing to a base plate, the pylon being traversed by at least one fluid pipe including a first end for connecting to the turbomachine and a second end for connecting to a fluid supply circuit, wherein the at least one pipe includes a movable portion movable in translation along the axis so as to be able to adjust the position along the axis of the first connecting end relative to the first longitudinal end. It also concerns a method of mounting an aircraft turbomachine on such a pylon.