  The paper presents the analysis of effective potentials of Dirac equations in
Schwarzschild and Reissner-Nordstroem fields. It is shown that in the majority
of the explored cases the condition of a particle "fall" to appropriate event
horizons is fulfilled. The exception is one of the solutions with normalizable
wave functions for the Reissner-Nordstroem extreme field, for which the
existence of the stationary bound state of half-spin particles is possible
inside the event horizon.
