U.S. Patent Specifications

In a metal rotor blade for rotary wing aircraft, a spanwise load carrying spar, a blade retention fitting by which the blade is adapted to be connected to a rotor hub, said fitting having upper and lower plate‐like members between which the root of said spar is receivable, fastening means extended through the overlapping portions of said spar and fitting, reinforcing plates between said members and said spar having perforate inboard portions through which said fastening means extend and imperforate portions out‐board of said fitting which overlie the upper and lower surfaces of said spar, and adhesive means between the imperforate portions of said plates and the surfaces of said spar for providing load carrying areas free from stress concentrations.