Collins Aerospace, a unit of RTX (NYSE: RTX), announced it has completed altitude testing of its Enhanced Power and Cooling System (EPACS), a next-generation Power and Thermal Management System designed for the F-35 fighter jet.

According to a press release, the system was operated for several days at power levels intended to replicate mission requirements. Testing was conducted across various altitudes to collect performance data and confirm the system's ability to deliver emergency power during operation. The results are said to validate system performance models.

"Successful altitude testing validates system performance in real-world flight conditions," said Ira Grimmett, vice president of Environmental & Airframe Control Systems for Power & Controls at Collins Aerospace. "Completing this phase of testing advances EPACS maturity and reinforces confidence in the system's capability and performance."

The altitude testing milestone follows a 2025 announcement by Collins Aerospace that EPACS had met requirements for aircraft integration. The company said EPACS is designed to provide increased cooling capacity to support planned technology upgrades for the F-35 and potentially future defense and commercial aircraft.

Collins Aerospace is headquartered in Windsor Locks, Connecticut, and employs approximately 80,000 people. Parent company RTX, based in Arlington, Virginia, reported 2025 sales of more than $88 billion.