Production and quality control of the new chambers with GEM technology in the CMS muon system

In 2019 during the second long shutdown (LS2) of the CERN Large Hadron Collider, the injector chain will be upgraded, allowing the instantaneous luminosity of the colliding beams to reach 2$\cdot10^{34}$ cm$^{-2}$s$^{-1}$ during the next run (Run$\thinspace3$). The CMS experiment will benefit from the increased total integrated luminosity collected, by improving the precision on the measurement of the Higgs couplings and the sensitivity to the new physics, providing that a suitable upgrade of the detector will allow it to cope the Run$\thinspace3$ data-taking conditions.Among the upgrades, the installation of a new station based on GEM technology (GE1/1), in the endcap of the Muon System will start in early 2019. The CMS GEM Collaboration is working on the production of the 144 GEM detectors to be installed, sharing the assembly and testing of the detectors among several production sites spread all over the world. A detailed common assembly protocol and quality control procedure (QC) have been deployed, with the ambitious goal to ensure standardization of the performance of the detectors produced by the different sites. In this contribution the results of the QC tests performed on the GEM chambers, assembled by the production sites following the common specification parameters, will be presented.