As an ongoing effort to achieve affordability goals and obtain additional aircraft orders, the C-17 program has developed and implemented a once-up / one-pass drilling process for the C-17 Cargo Ramp center skin to frame assembly operation. Traditionally, the aircraft assembly build process consists of the following steps: part assembly, multi-pass hole drilling, part disassembly, hole deburring, fay sealing, part re-assembly, and fastener installation. The once-up / one-pass drilling process reduces this sequence to: fay sealing, part assembly, one-pass hole drilling, and fastener installation. The new process will provide a significant recurring cost savings and cycle time reduction to the program by eliminating the labor and time-intensive efforts of disassembling, deburring, and re-assembling a skin panel 230 inches by 80 inches in size. This once-up / one-pass process has been achieved through a combination of assembly sequence changes, clamping method development, and drill motor / cutter system design.
