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F-35B fighter jets are assigned to Marine Corps Air Station Beaufort. File/Thad Moore/Staff 

A failed fuel tube has been identified as the cause of the crash of a military fighter jet in the fall in South Carolina, according to a new federal report.

The single-engine F-35B went down on Little Barnwell Island near Marine Corps Air Station Beaufort in late September. The pilot ejected safely. No one on the ground was injured.

The accident marked the first crash for the high-profile but troubled F-35 Joint Strike Fighter program. 

The Government Accountability Office cited the incident in an annual assessment of U.S. weapons systems that included comments about the jet and its performance deficiencies.

“An investigation determined a manufacturing defect caused an engine fuel tube to rupture during flight, resulting in a loss of power to the engine,” the agency said in the report released May 7.

The Pentagon has not released the results of its own probe, which is ongoing.

Lockheed Martin won a high-stake competition to build the Joint Strike Fighter in 2001, and the first jet took flight five years later. The engines are made by Pratt & Whitney, a division of United Technologies Corp.

The F-35 "B" variant was designed specifically for the Marines Corps to take off from short runways and land vertically, similar to Britain’s famous Harrier jet.

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The Beaufort-based aircraft that crashed was assigned to the 2nd Marine Aircraft Wing. Afterward, the U.S. and other nations grounded the entire fleet for up to 48 hours to check for faulty fuel tubes.

"If suspect fuel tubes are installed, the part will be removed and replaced," the Pentagon said in a statement in October. "If known good fuel tubes are already installed, then those aircraft will be returned to flight status."

The GAO said in its report last week that replacements were required on 117 jets and that most of the parts were swapped out by the end of 2018.

Contact John McDermott at 843-937-5572 or follow him on Twitter at @byjohnmcdermott