Composite Application for Rotorcraft Drive System Housings

Cast aluminum and magnesium are traditionally used in the fabrication of rotorcraft transmission gearbox housings, but these materials are susceptible to corrosion. Replacement is costly in terms of labor and down time, which creates the need for low cost, lightweight, corrosion-resistant materials. Composites are known to have superior corrosion resistance and higher damage tolerance than their metallic counterparts. Composites have superior strength and can be tailored to provide directional stiffness, which improves bearing concentricity/alignment and gear mesh contact. As part of research for the Great Lakes Composite Consortium MANTECH program and the Duel Usage Science and Technology program, Bell Helicopter developed a composite transmission housing for potential military use, and identified several rotorcraft drive system application issues. This paper summarizes the drive system housing composite technology developed to date, and addresses such housing issues as bonding of metallic inserts, O-ring wear due to exposed fibers, lightning strikes, and standard hardware applications.