The main rotor or rotary wing on the H-3 has five identical wing blades. Other helicopters may have two, three, or four blades. A typical wing blade is shown in figure 1-17. The rotary-wing blade is made of aluminum alloy, except the steel cuff by which the blade attaches to the rotor hub. The main supporting member of the blade is a hollow, aluminum alloy extruded spar, which forms the leading edge. The steel cuff is bolted to the root end of the spar. Twenty-three individual pockets constructed of aluminum ribs, aluminum channels, and aluminum skin covering are bonded to the aft edge of the spar.

Text and cutaway view: www.tpub.com courtesy