  FK Comae is a rapidly rotating magnetically active star, the light curve of
which is modulated by cool spots on its surface. It was the first star where
the "flip-flop" phenomenon was discovered. Since then, flip-flops in the spot
activity have been reported in many other stars.
  Therefore, it is of interest to perform a more thorough study of the
evolution of the spot activity in FK Com. In this study, we analyse 15 years of
photometric observations with two different time series analysis methods, with
a special emphasis on detecting flip-flop type events from the data.
  We apply the continuous period search and carrier fit methods on long-term
standard Johnson-Cousins V-observations from the years 1995--2010. The
observations were carried out with two automated photometric telescopes,
Phoenix-10 and Amadeus T7 located in Arizona.
  We identify complex phase behaviour in 6 of the 15 analysed data segments. We
identify five flip-flop events and two cases of phase jumps, where the phase
shift is \Delta \phi < 0.4. In addition we see two mergers of spot regions and
two cases where the apparent phase shifts are caused by spot regions drifting
with respect to each other. Furthermore we detect variations in the rotation
period corresponding to a differential rotation coefficient of |k|>0.031.
  The flip-flop cannot be interpreted as a single phenomenon, where the main
activity jumps from one active longitude to another. In some of our cases the
phase shifts can be explained by differential rotation: Two spot regions move
with different angular velocity and even pass each other. Comparison between
the methods show that the carrier fit utility is better in retrieving slow
evolution especially from a low amplitude light curve, while the continuous
period search is more sensitive in case of rapid changes.
