An oxidizer intake flow control system is disclosed for a gas turbine engine combustion chamber. The chamber has an oxidizer intake assembly which extends through the wall of the chamber such that an inlet aperture of the oxidizer intake and an exhaust aperture of the oxidizer intake are located on opposite sides of the wall defining the combustion chamber. An oxidizer intake sleeve defines a central passage through which oxidizer may pass into the combustion chamber. The intake passage extends along a central axis and the intake assembly is attached to the wall of the combustion chamber such that it is rotatable about this central axis. The inlet aperture and/or the exhaust aperture is located in a plane extending non-perpendicularly to the central axis. The combustion chamber may have several oxidizer intake assemblies extending through the combustion chamber walls. The intake assemblies may be interconnected such that they may be simultaneously rotated with respect to the combustion chamber wall.