An intermediate casing comprising an inner annular hub, an outer annular barrel and an annular part for separating flows situated between the hub and the outer barrel. A primary stream is delimited between the hub and the separation part. A secondary stream is delimited between the separation part and the outer barrel. At least one hollow arm extends radially from the hub to the outer barrel, passing through the primary and secondary streams. A transmission shaft extends radially in the hollow arm. The hollow arm comprises a hydraulic-fluid outlet situated downstream of the transmission shaft. The arm further comprises a bypass channel or pocket able to bypass the transmission shaft.