Method and apparatus for producing shims

A system for forming a shim on an aircraft airframe, the system comprising:

• measurement apparatus configured to:
• measure a surface of at least part of the aircraft airframe;
• and
• measure a surface of an aircraft skin for attaching to the at least part of the aircraft airframe;
• one or more processors configured to:
• create a digital model of the at least part of the aircraft airframe using the measurements of the surface of the at least part of the aircraft airframe;
• create a digital model of the aircraft skin using the measurements of the surface of the aircraft skin;
• digitally assemble the digital model of the at least part of the aircraft airframe with the digital model of the aircraft skin;
• and
• using the digitally assembled digital model of the at least part of the aircraft airframe and the digital model of the aircraft skin, create a digital model of a shim, the digital model of the shim substantially filling a gap between the digitally assembled digital model of the at least part of the aircraft airframe and the digital model of the aircraft skin;
• and
• Additive Manufacturing, AM, apparatus configured to form the shim directly onto the surface of the at least part of the aircraft airframe using the digital model of the shim.