[en] Thermal measurements on a convecting dilute ³He-superfluid ⁴He solution in the quasiperiodic regime show a transition from a mode-locked periodic state to chaotic time dependence via intermittency. In a region just below the onset of intermittency, injection of external multiplicative noise with noise amplitude above a certain threshold level induces the chaotic state. This noise-induced transition can be understood to be due to perturbation of a system with a barely stable attractor; the noise causing the system to escape the weakly attracting periodic points. We present numerical simulations and experimental data which support this picture. 13 refs., 13 figs