Abstract: A helicopter main rotor blade comprised of roll formed structure is provided. A C-shaped nose spar, a closure channel, a protective strip and a nose block are all roll formed. The nose spar extends the length of the leading edge of the helicopter blade, and is open to the rear between upper and lower trailing edge skins. The nose spar is flared adjacent the root whereby the trailing edges of the nose spar diverge from the leading edge as the nose spar extends toward the blade root. The closure channel is attached to the inside surfaces of the upper and lower trailing edges of the nose spar. The closure channel diverges from the leading edge as it extends toward said root. The protective strip is secured to a lead portion of the nose spar to capture a nose block against the leading edge of the nose spar.