We consider a linear model of interaction between a viscous incompressiblefluid and a thin elastic structure located on a part of the fluid domainboundary, the other part being rigid. After having given an existence anduniqueness result for the direct problem, we study the question ofapproximate controllability for this system when the control acts as anormal force applied to the structure. The case of an analytic boundary hasbeen studied by Lions and Zuazua in [9] where, in particular, a counterexample is givenwhen the fluid domain is a ball. We prove a result of approximatecontrollability in the 2d-case when the rigid and the elastic parts of theboundary make a rectangular corner and if the control acts on the wholeelastic structure.