A method for fabricating a one-piece composite fuselage section that minimizes out-of-plane fiber distortion. This is accomplished by fabricating a mandrel having a coefficient of thermal expansion in the hoopwise direction that is sufficiently greater than that of the laid-up composite ply assembly. As a result of this differential in the coefficients of thermal expansion in the hoopwise direction, the laid-up composite ply assembly is stretched circumferentially as the mandrel expands radially during cure, thereby eliminating or reducing out-of-plane fiber distortion. At the same time, the mandrel and part being fabricated should have substantially the same coefficient of thermal expansion in the lengthwise direction. As the outer surface of the mandrel increases in circumference, the circumferentially oriented reinforcing fibers of the inner plies are stretched, while the circumferentially oriented reinforcing fibers of the outer plies do not reduce in circumference and thus do not form waves or wrinkles.