A key design review for the F-35 fighter jet’s engine upgrade will take place several months later than originally predicted. An executive for Pratt & Whitney, the RTX-owned company that makes the jet’s F135 engines, revealed that the preliminary design review is expected to take place in May 2024, later than originally predicted. The F-35 Joint Program Office said the design review is “event driven” and has not been delayed. The F-35 is intended to carry more weapons and undergo other improvements, and the upgrade will be delivered in 2029. Pratt & Whitney’s president of military engines noted the company plans to test prototypes of its next-generation adaptive propulsion engine in the late 2020s.