  We study the interior structure of five dimensional neutral helical black
holes in Einstein gravity and charged helical black holes in Einstein-Maxwell
gravity. Inside the neutral helical black holes, the systems evolve to a stable
spacelike Kasner singularity. The metric field related to the helical
deformation strength exhibits oscillation behavior close to the horizon at low
temperature and small helical deformation strength. Inside the charged helical
black holes, we show that the inner Cauchy horizon can not exist. The systems
also evolve from the horizon to a stable Kasner singularity. We find that the
oscillations can exist and there is a special feature that the oscillations
occur near the horizon and before the collapse of the Einstein-Rosen bridge for
the charged helical black holes.
