RTX‘s [RTX] Collins Aerospace said on Monday that its Enhanced Power and Cooling System (EPACS)–the company’s proposed replacement for the F-35 fighter’s current Power and Thermal Management System (PTMS)–has undergone altitude testing at the company's Windsor Locks, Conn., site. "Altitude testing is a critical element of early development and risk reduction for a new PTMS," Collins Aerospace said. "The system was run for several days at power levels replicating mission requirements. It was pushed to operational limits in various altitudes…