F-35 engine undergoes mission testing at Arnold

The Pratt & Whitney F135 engine powers the F-35 Lightning II Joint Strike Fighter.

And now, the engine is back at Sea Level Test Cell 3, or SL-3, at Arnold Air Force Base, Tenn., for another round of accelerated mission testing, or AMT, to validate new hardware.

AMT provides a means to put engines through a full life cycle of operations in a compressed timeframe.

“The AMT is our primary vehicle to evaluate, validate and gain exposure time on upgrades or fixes to engine hardware that then flows into the reliability and maintainability of the weapon system,” said 1st Lt. Adam Doyle, a test manager with the Propulsion Test Branch, Test Division, Arnold Engineering Development Complex, or AEDC. “The bottom line to the warfighter is a system that is ready to fight more often and easier to maintain.”

A Pratt & Whitney F135 engine hangs in Arnold Engineering Development Complex (AEDC) Sea Level Test Cell 3 at Arnold Air Force Base, Tenn., during an inspection and maintenance period Sept. 2, 2021. The F135, used to power the F-35 Joint Strike Fighter, is undergoing Accelerated Mission Testing in the AEDC facility in support of Component Improvement Program efforts. (U.S. Air Force photo by Jill Pickett)

Testing new hardware in a ground test facility reduces safety risks for flight operations. The ability to obtain data of a full operational lifecycle of an engine in mere months helps speed the delivery of improvements to the fleet with reduced financial risk. Risk reduction is a key contribution to the Air Force of the developmental test and evaluation organizations of the Air Force Test Center, including AEDC.

The AMT currently underway is being conducted to assess 18 Component Improvement Program, or CIP, efforts. The CIP provides engineering support to in-service engine models with goals such as improving system operational readiness, reliability, and maintainability; and reducing engine life cycle cost.

Testing is expected to conclude in early 2022, at which time Doyle estimates they will have conducted 1,777 air-on sea-level hours and 135 RAM hours. During sea-level operations, the facility is operated at ambient air conditions. RAM operations involve using test facility compressors to increase engine inlet pressure and temperature simulating high-speed travel at low altitudes, a harsh environment for engine operations.

Over the course of these hours, the test plan calls for more than 5,000 total accumulated cycles, or TACs. A TAC is a measurement of engine operations accounting for various actions, such as powering up and achieving military thrust, which is responsible for wear and tear on the engine.

“I am repeatedly impressed by the discipline and drive of the entire AMT team,” said Lt. Col. Lane Haubelt, chief of the Propulsion Test Branch. “AMTs are a unique tool that allow insight into important questions on the reliability, maintainability, and cost of engine improvements well prior to their deployment across the entire fleet.

“The significant commitment required to execute an AMT highlights the importance of disciplined execution, robust analysis, and cooperation between AEDC, the engine manufacturer, and the program office. The extended hours in the control room and test cell, the long weekends inspecting and maintaining the test engine, and the countless days spent pouring over data ensure our warfighter and nation are equipped with reliable and cost-effective propulsion systems.”

A Pratt & Whitney F135 engine hangs in Arnold Engineering Development Complex (AEDC) Sea Level Test Cell 3 at Arnold Air Force Base, Tenn., between test runs Sept. 2, 2021. (U.S. Air Force photo by Jill Pickett)

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