System and method for forming perforations in a barrel section

A method of fabricating an engine inlet, comprising the steps of:

• providing an engine inlet inner barrel section as a one-piece composite sandwich structure cured in a single stage and having an inner face sheet and a honeycomb core;
• drilling, using a plurality of robotic drilling units, a plurality of perforations in the inner face sheet after final cure of the composite sandwich structure, wherein the drilling comprises indexing a hole pattern of the perforations to one or more cell walls of a honeycomb core of the composite sandwich structure, and positioning the hole pattern such that each perforation is located at a spaced distance from the cell walls;
• operating the plurality of robotic drilling units in synchronized movement with one another to simultaneously drill the plurality of perforations;
• and
• forming the plurality of perforations in a quantity providing a predetermined percent-open-area of the inner face sheet.