The Next Great Engine War Was Not What You Thought It Was
a deficit of 800 operational engines by 2030 (GAO, 2022). According to the GAO, two primary factors impacted sustainment costs. The first was unscheduled maintenance on the power module, which was significantly higher than anticipated due to a flaw in the turbine coating. Second, the engine depot at Oklahoma City Air Logistics Complex had insufficient capacity to repair modules, resulting in a large backlog. Furthermore, engine life was being decreased due to increased aircraft cooling requirements being placed on the engine. The F-35 uses its power and thermal management system (PTMS) to cool aircraft systems that generate heat, such as the avionics system. The PTMS is driven by bleed air pressure from the engine. While the engine had been designed to meet the air pressure requirements, subsequent upgrades to aircraft systems continued to increase the bleed air requirements (GAO, 2023a). When those upgrades were formalized in 2013, it was too late to redesign the engine without significant cost and schedule impacts. Therefore, program officials accepted the increased wear and tear on the engine. According to the GAO, the current Block 4 modernization efforts will require even more cooling capacity and bleed air than the PTMS, and engine can support and will exacerbate the engine life issues. The GAO estimates these cooling challenges have added $38 billion to the F-35’s life-cycle cost estimate. In response to these challenges, program officials have determined that it must upgrade the PTMS and engine to reduce life-cycle costs (GAO, 2023b).
Given the challenges of the F135, Congress doubled down on the Air Force’s continued lack of AETP transition planning and pushed the DoD to field AETP to the F-35A. Section 242 of the FY 2022 National Defense Authorization Act (NDAA) required DoD to develop an acquisition strategy for transitioning the engine to the Air Force’s
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Defense ARJ , Summer 2025, Vol. 32 No. 2: 104—130
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