Methods and apparatuses for controlling airflow proximate to engine/airfoil systems are disclosed. In one embodiment, an aircraft system includes an airfoil and an engine unit at least proximate to the airfoil with a gap between a portion of the airfoil and a portion of the engine unit. The system can further include a flow control device proximate to the gap and positionable among at least three stationary positions, including a retracted position in which the gap has a first area through which fluid can flow, a first extended position in which the gap is at least approximately aerodynamically sealed, and a second extended position in which the gap has a second smaller area through which fluid can flow. A control system can be coupled to the flow control device to move the flow control device among these positions.