Method of manufacturing an assembly having a nominal thickness skin panel

A method of manufacturing a panel assembly, comprising:

• supporting a panel assembly in a free state using a holding fixture, the panel assembly comprising a skin panel, and sacrificial material coupled to a skin panel inner surface respectively at interface locations for coupling the panel assembly to mating structure;
• acquiring a free state outer surface contour of the panel assembly by scanning a skin panel outer surface of the skin panel while the panel assembly is supported by the holding fixture;
• developing a numerical control (NC) machining program having cutter paths configured for machining the interface locations to an inner surface contour that is based on the free state outer surface contour;
• machining the sacrificial material by moving a cutter along the cutter paths while the panel assembly is supported by the holding fixture, and while the cutter is backed by a backing device applying backing pressure against the skin panel outer surface while the backing device moves in a coordinated manner in alignment with the cutter as the cutter moves along the cutter paths on the opposite side of the skin panel;
• removing the panel assembly from the holding fixture;
• and
• indexing the panel assembly and the mating structure to each other, and fastening the panel assembly and the mating structure together to result in a structural assembly.

A method of manufacturing an aerostructure of an aircraft, comprising:

• supporting a panel assembly of an aerostructure in a free state using a holding fixture in which the panel assembly has a geometric shape that is different than the geometric shape of the panel assembly in an as-designed nominal state, the panel assembly comprising a skin panel and sacrificial material coupled to a skin panel inner surface respectively at interface locations for coupling the panel assembly to mating structure, the skin panel having a skin panel outer surface configured to define an outer mold line (OML) that forms an aerodynamic contour of the aerostructure;
• acquiring a free state outer surface contour of the skin panel by scanning the skin panel outer surface while the panel assembly is supported by the holding fixture in the free state;
• developing a numerically controlled (NC) machining program having cutter paths configured for machining the interface locations to an inner surface contour that reflects nominal thicknesses of the panel assembly based on the free state outer surface contour;
• and
• machining the sacrificial material by moving a cutter along the cutter paths while the panel assembly is supported by the holding fixture, and while the cutter is backed by a backing device applying backing pressure against the skin panel outer surface while the backing device moves in a coordinated manner in alignment with the cutter as the cutter moves along the cutter paths on the opposite side of the skin panel.