Airframe production

A method of producing a first part of an aircraft airframe, the first part of the airframe being for attachment to a second part of an aircraft airframe, the method comprising:

• providing an initial structure, the initial structure being part of the first part of the aircraft airframe to be produced;
• providing a reference structure representative of the second part of the airframe;
• positioning the initial structure with respect to the reference structure such that the position and orientation of the initial structure relative to the reference structure is the same as the position and orientation relative to the second part of the airframe that the initial structure would have if the first part of the aircraft airframe was attached to the second part of the airframe;
• specifying a surface, the surface being a desired inner mould line for the first part of the aircraft airframe;
• applying, to an outer surface of the initial structure, one or more layers of material;
• and
• after the one or more layers of material have been applied to the initial structure, machining, using a cutting device, the layers of material such that the position and orientation of the outer surface of the layers of material with respect to the reference structure is the same as the position and orientation with respect to the second part of the airframe that the specified surface would have if the first part of the aircraft airframe was attached to the second part of the airframe;
• measuring a plurality of points on a surface of the reference structure;
• and
• using the measurements of the surface of the reference structure, determining a datum;
• and
• the step of machining comprises controlling the cutting device with respect to the datum.