  We present a qualitative search for ultra-fast outflows (UFOs) in excess
variance spectra of radio-quiet active galactic nuclei (AGN). We analyse 42
sources from the Tombesi et al. (2010) spectroscopic UFO detection sample, and
an additional 22 different sources from the Kara et al. (2016) variability
sample. A total of 58 sources have sufficient observational data from
XMM-Newton EPIC-pn and variability for an excess variance spectrum to be
calculated. We examine these spectra for peaks corresponding to variable
blue-shifted H- and He-like ion absorption lines from UFOs. We find good
evidence for such outflows in 28% of the AGN sample and weak evidence in a
further 31%, meaning that $\sim$ 30-60% of the AGN sample hosts such UFOs. The
mean and median blue-shifted velocity is found to be $\sim$ 0.14c and 0.12c,
respectively. Current variability methods allow for a fast, model-independent
determination of UFOs, however, further work needs to be undertaken to better
characterize the statistical significance of the peaks in these spectra by more
rigorous modelling. Detecting good evidence for variable UFO lines in a large
number of sources also lays the groundwork for detailed analysis of the
variability timescales of the absorbers. This will allow us to probe their
densities and hence distances from the central super-massive black hole.
