NATIONAL HARBOR, MD -- Air Force Secretary Frank Kendall said this week he supports an F-35 engine replacement program that capitalizes on the billions of dollars the service has invested in adaptive propulsion technology, but said questions remain about affordability. “There’s some technical issues there, but the fuel savings and the increase that we could get on that have a lot of value,” Kendall told reporters during the Air Force Association’s annual Air, Space and Cyber conference. The F-35 joint...