  The Majorana fermions propagating along the edge of a topological
superconductor with $p_x+ip_y$ pairing deliver a shot noise power of
$\frac{1}{2}\times e^2/h$ per eV of voltage bias. We calculate the full
counting statistics of the transferred charge and find that it becomes
trinomial in the low-temperature limit, distinct from the binomial statistics
of charge-$e$ transfer in a single-mode nanowire or charge-$2e$ transfer
through a normal-superconductor interface. All even-order correlators of
current fluctuations have a universal quantized value, insensitive to disorder
and decoherence. These electrical signatures are experimentally accessible,
because they persist for temperatures and voltages large compared to the
Thouless energy.
