Aviation Ordnanceman (abbreviated as AO) is a United States Navy occupational rating.I-level perform maintenance on bomb racks, missile launchers, and all other aircraft armament components."I" level ordnancemen work in the aviation intermediate maintenance departments on ships at sea or in facilities ashore.They perform such tasks as preventive maintenance, testing of bomb racks, missile launchers, rocket launchers, handling equipment, loading equipment, aircraft guns for issue to squadrons, and perform any repairs needed.One of the most notable aviation ordnancemen was Lieutenant John William Finn, who came up as an enlisted sailor making it to the rank of chief petty officer.