At investigation in a square-law approximation on amplitude of cappilary oscillations of a heavily charged drop is shown, that in a cause of interaction of various modes of cappilary oscillations the losses of a stability by a drop having a charge smaller then critical, can be initiated by virtual excitation not only basic, but any of modes or linear combination of several arbitrary modes. The analysis of regularities of formation of a linear combination of several arbitrary modes. The analysis of regularities of formation of a spectrum of modes and losses of a stability by some their them, excited owing to interaction in the second order of smallness of several modes is carried spent, which perturbation is set in an initial instant.