Some F-35 Joint Strike Fighters will require additional inspections after investigators identified a possible problem with two more fuel supply tubes, the Pentagon's F-35 Joint Program Office said Thursday.
"In addition to the previously identified failed tube, the analysis has identified two additional fuel supply tubes that require inspection," JPO spokesman Joe DellaVedova said in a statement.
Defense News was first to report that the additional inspections may temporarily halt flight operations specifically for the Marine Corps' F-35B variant. The Marine Corps variant of the aircraft has a built-in lift fan, giving it the ability to take off and land vertically.
"The Marine Corps is conducting additional inspections on the F-35 to maintain fleet safety standards," said Capt. Christopher Harrison, a Marine spokesman at the Pentagon. "Engineering data collected during the ongoing investigation established the requirement for a time-phased inspection based on engine flight hours. F-35 operations continue on all aircraft with engines that have not reached the inspection requirements."
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While the two fuel tubes being inspected have not failed, DellaVedova said, engineering data collected identified the need to take a look at the aircraft with higher engine flight hours.
"The inspection maintains F-35 fleet safety standards as older engines may require fuel tube replacement," DellaVedova added.
The Joint Program Office also declined to address questions about the number of aircraft that could be affected by the fuel-tube inspections.
"The exact number of engines that may require fuel tube replacement speaks to the readiness status of the fleet, and will not be addressed by the JPO," DellaVedova said, adding, "The procedure to inspect and replace can be done by flight line maintenance without removing the engine."
While DellaVedova said the procedure to inspect and replace the tubes can be completed within 24 to 48 hours, he did not say how long flight operations could be paused for some jets as a result. "F-35 operations continue on all aircraft with engines that have not reached the inspection requirements," he said.
An F-35B detachment from Marine Fighter Attack Squadron 211, based out of Arizona, is currently operating in the Middle East with the 13th Marine Expeditionary Unit. Officials with the unit did not immediately respond to questions about whether the new round of inspections has sidelined any of its fighter jets.
The Pentagon last Monday approved more than 80 percent of its operational F-35 fifth-generation fighter to fly again after mandated inspections from the aircraft's Joint Program Office grounded the entire fleet earlier this month.
The Defense Department had temporarily suspended F-35 flight operations so that maintainers could conduct a fleet-wide inspection of a potentially faulty fuel tube inside the aircraft's engine.
DellaVedova said the joint government and industry technical team recently completed their assessment of the fuel supply tubes within the Pratt & Whitney engine on F-35 aircraft.
Editor's Note: This article has been updated. The inspections do not require engines to be removed from the aircraft.
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