Hub assembly

A hub assembly for a helicopter having a rotor shaft including axially spaced apart upper and lower annular mounting flanges, at least one of the mounting flanges extending radially outwardly from the shaft and defining a generally radially disposed mounting surface, said hub assembly comprising a monolithic thin-wall hub shell having plate-like upper and lower wall portions integrally joined only at the outer periphery of the hub shell and spaced apart at inner regions of said hub shell, said upper and lower wall portions having coaxially aligned and axially spaced central apertures communicating with the interior of said hub shell for receiving the rotor shaft coaxially therethrough, said hub shell having means for retaining it in assembled relation with the rotor shaft and with the central axis of the hub shell coaxially aligned with the axis of the rotor shaft for rotation with the rotor shaft and including at least one annular retaining flange surrounding an associated one of said central apertures and having a generally radially disposed seating surface for seating engagement with said mounting surface, said upper and lower wall portions defining a plurality of integral bearing retaining sockets angularly spaced relative to said hub shell axis and webs integrally joined to and extending between said bearing retaining sockets, each of said bearing retaining sockets including an integral end wall at the radial outer end thereof, said end wall having an aperture therethrough and a generally radially inwardly facing bearing surface surrounding said aperture, a plurality of blade retention bearings, each of said blade retention bearings received within an associated one of said bearing retaining sockets, each of said blade retention bearings having annular laminates for receiving therethrough the shaft of an associated rotor blade, each of said blade retention bearings having an outer end member including a radially outwardly facing seating surface engaging an associated bearing surface, and means for releasably retaining each of said blade retention bearings in assembled relation with said hub shell with the seating surface thereof in complementary face-to-face engagement with an associated bearing surface, at least one of said central apertures being of sufficient size to allow a blade retention bearing to pass freely therethrough when said hub assembly is out of assembled relation with the rotor shaft to allow assembly of said blade retention bearings within said hub shell.