François Brun made important contributions both to the commissioning and the analysis tools for the large (28 m) H.E.S.S. telescope, CT5. He was responsible for the Central Trigger system during the installation of CT5 and had to adapt the Central Trigger to allow the operations of CT5 together with the smaller telescopes. As the central trigger expert, he played a major role in the campaign leading to the first light of H.E.S.S. II array. He also worked on the calibration of H.E.S.S. I cameras and was able to identify and correct the cause of common mode noise in the pedestals. On the analysis side, François Brun has developed tools for the H.E.S.S. Galactic Plane Survey analysis. He has also developed original methods to identify variable sources of time-scales larger than a minute in H.E.S.S. fields. As a member (and former co-convenor) of the analysis and reconstruction working group, where he plays a major role, he has provided a support to a large number of on-going analyses.