Assembly for turbine machine with open rotor contra-rotating propellers, comprising a small duct for the passage of ancillaries

An assembly for an aircraft turbine machine including a receiver for a pair of open rotor contra-rotating propellers, the assembly including a duct, ancillaries routed inside the duct, an attachment case, attachment device of the duct on an annular installation portion of the case. The attachment device in an assembled configuration include a split ring fitted with internal projections housed inside orifices in the duct; a radial loading surface of the ring made on the portion the surface being tapered and narrowing along a first axial direction, and being in contact with a peripheral surface of the complementary shaped tapered split ring; device of axially loading the ring along the first direction, the device being blocked in the axial direction on the portion.