Mechanical and Structural Aspects of the C-17 Cargo Ramp and Cargo Door ADFS

The cargo ramp and cargo door are two major C-17 components that are built in St. Louis, MO and shipped by rail for final assembly in Long Beach, CA. A major portion of the total build time for the ramp and door assemblies consisted of the hand installation of approximately 16,000 moldline fasteners and 19,400 moldline fasteners, respectively, attaching the skin to the substructure. In addition, several thousand fasteners are also installed in the floor sections of the ramp and door. A major cost savings opportunity existed to reduce the cost of the ramp and door assemblies by automating the installation of these fasteners. Boeing-St. Louis contracted Brotje Automation of Wiefelstede, Germany to design and build an automated drilling and fastening system (ADFS). Automation is expected to reduce cost by reducing the time required to build the ramp and door assemblies. In addition, automation is expected to improve fastener hole quality and fastener installation quality. Another important reason for undertaking this project was to enable Boeing-St. Louis to strengthen its position as an industry leader and innovator in aerospace manufacturing. This paper describes the mechanical and structural challenges (associated with hoisting and supporting the assemblies) that were overcome to implement this initiative.