Abstract: The invention relates to an assembly for a turbine engine (1), the assembly including: a casing (20) extending along a longitudinal axis (X-X?) of the turbine engine (1), a surface heat exchanger (100) arranged along an inner edge (22) of said casing (20) and including a plurality of cooling fins (110) extending radially inwards and longitudinally, and a central body (30) partially concentrically arranged within said casing (20), said casing (20) and the central body (30) defining between one another an annular air channel (Va), the width (hVa) of which is substantially constant in the region of the heat exchanger (100). The assembly is characterized in that the fins (110) are distributed over more than 180° of the inner edge (22) of the casing (20) and in that the mean height ((hMOV) of the fins (110) is more than 5% of the width (hVa) of the annular air channel (Va) in the region the heat exchanger (100).