The challenge was to create large, 100 percent titanium engine bay doors with complex contours to provide ground personnel with service access to the F-22's engines. Aerostructures responded by applying its patented liquid interface diffusion (LID) bonding process to prototype and build these structures. But while the division had used LID bonding to make engine ducts, nozzle assemblies, and other "hot" engine components before, the stringent requirements of the F-22 program necessitated 9 key technical advance.

This involved the development of a bonding method that improved the way pressure was applied between the inside and outside of the sandwich structure during the LID bonding process, ensuring a better bond.