**GAO-11-903R**                      Published: Sep 14, 2011. Publicly Released: Sep 19, 2011.                  

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## Highlights

After supporting a Joint Strike Fighter (JSF) acquisition strategy that called for a competitive engine development of the F135 and F136 engines, the Department of Defense (DOD) stopped requesting funding for the F136 alternate engine in its fiscal year 2007 budget request, but the Congress continued to fund it through the 2010 budget. In February 2010, DOD projected that it would cost an additional $2.9 billion through 2016 to support an alternate engine program. DOD decided that an engine competition would not likely generate enough long-term savings to justify this up-front investment and subsequently terminated the alternate engine program. In 2010, at congressional request, we reviewed the basis for DOD's $2.9 billion funding projection and reported that the projection did not include the same level of fidelity and precision normally associated with a detailed, comprehensive cost estimate and that the amount of up-front investment needed could be lower if two key assumptions in DOD's analysis were changed. Moreover, since DOD's projection and our last review, several fundamental changes in the JSF aircraft and engine programs have taken place. We examined the potential implications of these changes to the $2.9 billion funding projection. We also examined the potential implications for DOD's broader cost-benefit analysis that captures the long-term costs and benefits of the competitive engine program.

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Michael J. Sullivan
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## Topics

National Defense

Aircraft enginesCost analysisCost effectiveness analysisDefense capabilitiesDefense cost controlDefense procurementFighter aircraftFuture budget projectionsInvestmentsMilitary aircraftMilitary engineeringMilitary technologyProcurement planningProgram evaluationSole source procurementTechnology assessmentCost estimates