The decision to replace a successful automated production system at the heart of a high volume aircraft factory does not come easily. A point is reached when upgrades and retrofits are insufficient to meet increasing capacity demands and additional floor space is simply unavailable. The goals of this project were to increase production volume, reduce floor space usage, improve the build process, and smooth factory flow without disrupting today’s manufacturing. Two decades of lessons learned were leveraged along with advancements in the aircraft assembly industry, modern machine control technologies, and maturing safety standards to justify the risk and expense of a ground-up redesign. This paper will describe how an automated wing spar fastening system that has performed well for 20 years is analyzed and ultimately replaced without disturbing the high manufacturing rate of a single aisle commercial aircraft program.