Planetary reduction gear ring gear for a turbine engine

Ring gear of a planetary reduction gear for a turbine engine, in particular of an aircraft, said ring gear extending about an axis (X) and comprising first and second coaxial annular elements and comprising respectively two inner annular teeth oriented differently, said first and second annular elements further comprising respectively first and second radially external annular flanges to secure said first and second elements to one another, the teeth of said first and second annular elements being axially spaced from one another and from a joint plane (P) of said first and second flanges, and defining between them an annular space externally delimited by two annular rims supporting respectively said flanges, at least one of the flanges comprising at the level of said joint plane notches that are substantially radial for the oil to pass through by centrifugation, wherein it further comprises an annular row of oil-retention walls protruding from said rims in said space.