Abstract: A mounting frame for avionic trays which accommodates various tray sizes and provides a structrual member which also serves as a wire bundle and terminal block support and provides for an integral plenum that receives hot air and distributes cooling air. A seal and orifice assembly feature in the shelf assembly includes seal cross section geometry suitable for accommodating an adjustable lip feature which adapts to the variable tolerance encountered in the avionic box tray assembly interface. The metal ground terminal block utilizes poke-home electrical pins and sockets which are mounted to structure with rivets, thereby establishing ground contact with the aircraft structure.