The Pratt & Whitney F135 short takeoff/vertical landing (STOVL) variant propulsion system took one more step toward government certification recently with the successful completion of one of the most rigorous, demanding tests in the entire qualification program. Pratt & Whitney is a United Technologies Corp. company.

The high temperature margin test which took place at Arnold Engineering Development Center (AEDC) in Tennessee involves intentionally running the engine to turbine temperatures beyond design conditions while simultaneously operating the turbo-machinery at or above 100 percent of design conditions.

"While these are conditions the F135 engine will not experience during normal field operations, the purpose of this test is to demonstrate design margin at the most extreme operating conditions that could possibly exist," explained Tyler Evans, Director of F135 engine programs. "This is without a doubt one of the most demanding tests for an F-35 engine and the F135 passed the test with flying colors."

The test also demonstrated the F135 propulsion system's ability to produce margin relative to thrust with this engine producing 28 percent more thrust than the specification requirement.

"The F135 engine continues to exceed performance expectations to deliver the most advanced, capable fifth generation fighter engine for the F-35," Evans said. "The engine that completed this test is in excellent condition. It will now complete STOVL powered lift performance qualification testing in West Palm Beach, one of the last steps prior to receiving Initial Service Release qualification from the government."

The Pratt & Whitney F135 continues its steady progress through development testing and validation into full production and sustainment. The F135 has completed more than 19,000 hours of testing and the Conventional Takeoff and Landing (CTOL) / Carrier Variant (CV) engine received Initial Service Release (ISR) in February indicating that the engine has met ISR requirements for safety, reliability, durability and performance, and is now cleared for use in the field. Pratt & Whitney has delivered all flight-test engines required for the program as well as the first 10 production engines. The STOVL F135 engine is scheduled to receive ISR certification before the end of the year.