An apparatus (10) that houses functional components of a mechanical assembly includes a frame component (12) formed of a first material, the frame component (12) bearing primary load, torque or pressure applied to the apparatus (10) during operation of said mechanical assembly. The housing apparatus (10) further includes a composite reinforcement component (130) for resisting forces applied to the apparatus during operation of the mechanical assembly and an enclosure component (80) formed of a second material of lower density than the first material of the frame component (12), the enclosure component (80) covering and sealing at least the functional components of the mechanical assembly from external conditions during operation of the mechanical assembly.