F-35 engine upgrade hits delay, casting doubt on timeline

PARIS—A key milestone for the Pentagon’s program to upgrade the F-35 engine has been pushed back a year, raising questions about the overall timeline of the effort. The engine upgrade will reach “critical design review,” a milestone that essentially closes the design phase of the program, by “mid-next year,” according to Jill Albertelli, president of military engines for Pratt & Whitney—a year later than Pratt previously estimated. The upgr