Aeroelastic stability remains an important concern for the design of modern structures such as wind turbine rotors, more so with the use of increasingly flexible blades and military aircrafts with increasing maneuvering capabilities etc. A nonlinear aeroelastic system has been considered in the present study with parametric uncertainties. The analysis has been put in a stochastic framework and the propagation of system uncertainties have been quantified in the aeroelastic response. A spectral uncer- tainty quantification tool called Polynomial Chaos Expansion has been used. A projection based non-intrusive Polynomial Chaos approach is compared to its classical Galerkin based counterpart, and proven to be more efficient as order of chaos expansion increases. Effect of system randomness on the bifurcation behavior and the flutter boundary has been significant. Stochastic bifurcation results and bifurcation of probability density functions are presented here. Copyright © 2010 by ASME.