Precision　manufacturing　and　intelligent　assembly　in　the　aeronautic　industry　pose　new　challenges　for　the　design　of　Flexible　Manufacturing　Systems　(FMSs).　To　address　these　issues,　a　modular　Parallel　Kinematic　Machine　(PKM)-based　hybrid　machine　tool　is　proposed.　The　5-axis　hybrid　machine　tool　is　conceptually　designed　by　integrating　3-Degree-Of-Freedom　(DOF)　over-constrained　PKMs　with　a　2-DOF　serial　mechanism　including　a　unique　double-circumferential　guideway.　By　integrating　accessory　devices,　the　proposed　machine　provides　a　promising　alternative　solution　to　building　a　novel　FMS　for　the　flexible　manufacturing　requirements　of　larger　arc-shaped　aeronautic　components.　A　kinematic　model　is　established　to　conduct　an　inverse　kinematic　analysis　to　predict　the　reachable　workspace　by　using　a　‘sliced　partition’　searching　algorithm.　To　evaluate　the　kinetostatic　performance　of　the　hybrid　machine　tool,　a　modified　kinetostatic　model　is　established　by　including　the　compliances　of　all　joints　and　limb　structures.　The　prediction　accuracy　of　the　proposed　kinetostatic　model　is　validated　by　numerical　simulations.　Two　kinetostatic　performance　indexes,　the　average　reaction　index　and　the　average　displacement　index,　are　formulated　and　applied　to　reveal　the　gravity-caused　joint　reactions　and　elastic　displacement　of　the　hybrid　machine　tool,　respectively.　The　analyses　show　that　the　kinetostatic　performances　of　the　machine　are　heavily　affected　by　gravity;　thus,　gravity　must　be　considered　during　the　early　design　stage.　Notably,　with　minor　revisions,　the　proposed　kinetostatic　model　and　performance　indexes　can　be　applied　to　other　hybrid　mechanical　systems　to　efficiently　evaluate　their　kinetostatic　performances.　©　2018　Elsevier　Ltd