Pratt & Whitney is pitching a set of F135 engine upgrade options for the Joint Strike Fighter the company says could save the government billions in future sustainment costs and provide the engine performance needed to support Block 4 capabilities. The F-35 joint program office has not established a formal requirement for an F135 engine upgrade or replacement, but as part of a study to inform that process, it commissioned proposals from engine-maker Pratt & Whitney. The company in March...