The other work included repairing the plane’s stealthy coatings and flight controls. The U.S. Air Force has just wrapped up an overhaul of its fleet of F-22 Raptor fighters. The massive upgrade, conducted at Hill Air Force base in Utah, included structural repairs to extend the service lives of the fighter jets, and fixes to each fighter’s anti-radar stealth coating. The planes also received inspections and refurbishment of the flight control system. The work involved taking all of the jets through “six unique maintenance machines for structural repair, modification, coatings restoration, and aircraft damage repair,” according to the Air Force, as well as performing “structural modifications to increase total flying hour serviceability on each aircraft by 8,000 hours.”