The U.S. Navy, Air Force and Marines — as well as 11 international partners who participated in the program — grounded all F-35 fighters on Thursday as part of an ongoing investigation into a jet that crashed in Beaufort, South Carolina, late last month.
A Navy aircraft mishap board is charged with overseeing the investigation, and they will be conducting a fleet-wide inspection of a fuel tube inside the engine of the F-35 aircraft, according to military officials.
"The primary goal following any mishap is the prevention of future incidents," Joe Dellavedova, the director of public affairs for the F-35 program, said in a statement. "We will take every measure to ensure safe operations while we deliver, sustain and modernize the F-35 for the warfighter and our defense partners."
Dellavedova said that they will remove and replace any fuel tubes they suspect might be problematic. Those planes that don't have the problem will be cleared to fly, he said, and they hope to have the inspections completed within 24 to 48 hours.
This is only the latest turbulence for a long troubled flight program that began in October 2001. A Government Accountability Office report to Congress in June 2018 showed that the fighter grew increasingly expensive and regularly missed its deadlines, forcing the program to completely restructure in 2010 after moving its financial goal posts multiple times.
The office recommended in its June report that the Department of Defense "resolve all critical deficiencies before full-rate production."
The United States has spent over $320 billion so far to develop and acquire more than 2,400 fighter jets, according to the GAO report.
Dr. Michael Gilmore, the director of Operational Test and Evaluation at the Department of Defense until 2017, also provided a fairly searing depiction of the F-35 program in his FY 2015 Annual Report. He wrote that it would be problematic to make any commitment to a block purchase of the F-35 before November 2021 because of the technical challenges the program faced, but he did not identify fuel tubes as a specific issue.
"Is it prudent to further increase substantially the number of aircraft bought that may need modifications to reach full combat capability and service life?" Gilmore wrote in the report, questioning the decision to commit to a block purchase.
"As the program manager has noted, essentially every aircraft bought to date requires modifications prior to use in combat."
Gilmore, who left the office in 2017, and his successor, Robert Behler, could not be immediately reached for comment about the decision to ground the F-35 on Thursday.
Dellavedova told NBC News that this latest issue would not impact the Pentagon's decision to pursue a bulk purchase of the fighter from Lockheed Martin, noting that they were able to negotiate a 5.4 percent price decrease with the defense contractor to bring it to just under $90 million per aircraft.
"The F-35 is a combat proven aircraft," he argued. "It was just last month the Marine Corps used the F-35 to conduct combat operations in Afghanistan."