  Structured jets are recently invoked to explain the complex emission of gamma
ray bursts, such as GW 170817. Based on the accretion simulations, the jets are
expected to have a structure that is more complex than a simple top-hat. Also,
the structure of launching regions of blazar jets should influence their large
scale evolution. This is recently revealed by the interactions of jet
components in TXS 0506+056, where the jet is observed at a viewing angle close
to zero. Observational studies have also shown an anti-correlation between the
jet variability, measured e.g. by its minimum variability time scale, and the
Lorentz factor, that spans several orders of magnitude and covers both blazars
and GRBs samples. Motivated by those observational properties of black hole
sources, we investigate the accretion inflow and outflow properties, by means
of numerical GR MHD simulations. We perform axisymmetric calculations of the
structure and evolution of central engine, composed of magnetized torus around
Kerr black hole that is launching a non-uniform jet. We probe the jet
energetics at different points along the line of sight, and we measure the jet
time variability as localized in these specific regions. We quantify our
results by computing the minimum variability timescales and power density
spectra. We reproduce the MTS-$\Gamma$ correlation and we attribute it to the
black hole spin as the main driving parameter of the engine. We also find that
the PDS slope is not strongly affected by the black hole spin, while it differs
for various viewing angles.
