Yes, FLARM is approved by EASA for installation is certified aircraft. In light airplanes, FLARM can be installed either as a Standard Change (CS-SC051b) or as an EASA approved Minor Change (MCA) based on an Approved Model List (AML). The difference is that the Standard Change is limited to VFR day. The Minor Change does not have such limitations. Both options require an approved AFM Supplement. The MCA together with the EASA approved AFM Supplement and other required documents, for use both as a Minor Change or Standard Change installation, can be acquired here.