  The observed clustering of ultra-high energy cosmic rays suggests the
existence of a neutral component. The models with violation of Lorentz
invariance may explain this component by neutrons becoming stable above some
threshold energy E_0. The protons, in turn, may become unstable above some
energy E_1>E_0. We calculate the dependence of the threshold energies E_0 and
E_1 on the parameters of the model and find E_1/E_0\gsim 1.5. We argue that the
characteristic threshold behavior of charged and neutral components may be used
as the specific signature of models with violation of Lorentz invariance. The
existence of the neutron stability threshold E_0 can be investigated with
already existing data.
