A rotor mast including an outer member defining a channel therethrough and an inner member disposed in the channel through the outer member, wherein the inner member is configured to apply a compressive force to the outer member.

A rotor blade retention assembly is configured to connect a rotor blade to a central hub comprising a hub arm coupled to and extending radially outward from a hub bowl. The hub arm includes a hub arm lug. The rotor blade retention assembly includes a tension-torsion strap with an inboard end and an outboard end, the inboard end including an inboard pin hole and the outboard end including an outboard pin hole. The rotor blade retention assembly further includes an inboard blade pin and an outboard blade pin. The inboard blade pin is configured to extend through the hub arm lug and the inboard pin hole and to couple the inboard end of the tension-torsion strap to the hub arm. The outboard blade pin is configured to extend through a blade lug of a rotor blade and the outboard pin hole and to couple the outboard end of the tension-torsion strap to the rotor blade.

A rotor mast including an outer member defining a channel therethrough and an inner member disposed in the channel through the outer member, wherein the inner member is configured to apply a compressive force to the outer member.

A box frame hub arm structure is provided and includes a body having an outboard surface, which is disposable to abut with an inboard surface of an outboard arm of an aircraft rotor head, and lead/lag sides. The body is formed to define a first cavity, an aperture communicative with the first cavity through the outboard surface and second and third cavities. The second and third cavities extend outwardly in opposite lead/lag directions from the first cavity to the lead/lag sides.

A rotor hub assembly includes an open rotor hub assembly with an open rotor hub and a mounting plate. The open rotor hub includes an annular base portion with periphery and a plurality of rotary member portions arranged about the annular base portion that each define an aperture for receiving a rotor blade. The mounting plate spans the annular base portion and is coupled to the annular base portion by a resilient member to accommodate radially expansion and contraction of the annular base portion according to loads exerted on the rotor hub by rotor blades seated in the apertures of the rotary member portions.

A rotor hub assembly includes an open rotor hub assembly with an open rotor hub and a mounting plate. The open rotor hub includes an annular base portion with periphery and a plurality of rotary member portions arranged about the annular base portion that each define an aperture for receiving a rotor blade. The mounting plate spans the annular base portion and is coupled to the annular base portion by a resilient member to accommodate radially expansion and contraction of the annular base portion according to loads exerted on the rotor hub by rotor blades seated in the apertures of the rotary member portions.

A pitch bearing assembly includes an inboard pitch bearing including an inner race and an outer race, the outer race including a radially outwardly protruding tab, and an outboard end of the inboard pitch bearing including a plurality of rotation transmitting features. An outboard pitch bearing of the pitch bearing assembly includes an inner race and an outer race, an inboard end of the outer race of the outboard pitch bearing including a plurality of rotation transmitting features. A coupler of the pitch bearing assembly has an inboard end and an outboard end, the inboard end of the coupler having a plurality of rotation transmitting features engageable with the rotation transmitting features of the inboard pitch bearing, the outboard end of the coupler having a plurality of rotation transmitting features engageable with the rotation transmitting features of the outboard pitch bearing.

A box frame hub arm structure is provided and includes a body having an outboard surface, which is disposable to abut with an inboard surface of an outboard arm of an aircraft rotor head, and lead/lag sides. The body is formed to define a first cavity, an aperture communicative with the first cavity through the outboard surface and second and third cavities. The second and third cavities extend outwardly in opposite lead/lag directions from the first cavity to the lead/lag sides.