Assembly method for a gas turbine fan drive gear system

An epicyclic gear train (22) employs a unitary carrier (34) in which spaced side walls (60) are interconnected with circumferentially spaced mounts (54). Apertures (98) are provided between the mounts at an outer circumference of the carrier (34), and gear pockets are provided between the walls (60) and the mounts (54) and extend to the apertures. At least one of the walls (60) has a central opening (100). To assemble the gear train, an intermediate gear (32)is inserted through the central opening (100) and moved radially into the gear pocket (102) to extend through the aperture (100). A baffle (68) is then inserted into the carrier (34), and a sun gear (28) is inserted through the central opening (100) to intermesh with the intermediate gear (32).