Lockheed Martin has grounded the F-35 to fix a newly-discovered software problem that can cause a fuel boost pump to shut down in flight.
The manufacturer announced the grounding order only a few hours after releasing a statement saying the F-35 was restricted from operating above 10,000ft (3,050m) because of the same problem.
The grounding, revealed on 1 October, is expected to last at least through "early next week" while Lockheed and fuel boost pump supplier BAE Systems install a fix, which has already been identified, Lockheed says.
One of the F-35's three variants could still face flight restrictions even after the grounding order is lifted.
All flights in short take-off and vertical landing mode are also suspended after a post-flight inspection on the BF-1 flight test aircraft detected an "issue" with the auxiliary inlet door hinge located immediately aft of the lift fan.
Lockheed is still working to identify the root cause of the auxiliary inlet door hinge issue that has stopped all STOVL-mode tests.
The STOVL-capable F-35B has to complete at least 50 vertical landings to clear the flight envelope to launch a series of shipboard tests scheduled in March 2011. Completing shipboard testing is critical to meeting the US Marine Corp's plan to enter service with the F-35B in December 2012.
A series of previous reliability problems, including with the inlet doors activated during STOVL flight, had caused the F-35B type to fall further behind schedule in June and July, although the number of flight tests rebounded in August.
The software-based grounding and the STOVL restrictions mean the F-35B could fall further behind schedule with two years left to stand up the first operational unit for the USMC.