Skilled artisans from the F-22 Raptor Depot Maintenance Team install the night air-to-air refueling, or NAAR, modification on an F-22 in this 2007 file photo. F-22 work at Hill Air Force Base began on April 3, 2006, and involved modifying the aircraft to add lights that improve NAAR capability. Eighteen jets were modified as part of the workload, with the first one completed on May 12, 2006. (Courtesy photo)