The F-35 Joint Program Office (JPO) has temporarily grounded the Lockheed Martin F-35B short take-off/vertical landing (STOVL) variant of the tri-service stealth fighter after the failure of a fueldraulic line in the aircraft's propulsion system. The fueldraulic line powers the actuator for the F-35B's STOVL exhaust vectoring system.
F-35B flight operations have been suspended at NAS Patuxent River, Maryland, Eglin AFB, Florida, MCAS Yuma, Arizona, and at Lockheed Martin's production facility in Fort Worth, Texas. Flight operations for the US Air Force's F-35A and the US Navy's F-35C model aircraft are unaffected.
"The F-35 Joint Program Office issued a precautionary suspension of flight operations today for development and test F-35B Short Takeoff and Vertical Landing (STOVL) variants," the JPO says. "These actions were taken as a result of an incident involving an F-35B at Eglin AFB. The precautionary flight suspension preserves safety while providing time for the program to understand the origin of a failure of a propulsion fueldraulic line."
According to the JPO, the incident occurred on 16 January at about 10 am central time. "While initiating a conventional mode takeoff roll, the aircraft experienced a propulsion system fueldraulic failure prior to takeoff," the JPO says. "Following standard operating procedures, the pilot aborted takeoff without incident and cleared the active runway. There were no injuries to the pilot or ground crew. The jet was then safely towed to a maintenance hangar and secured."
Engineering teams are reviewing data from the incident in order to determine the root cause of the failure, the JPO says. Once Lockheed and the JPO understand what caused the problem, the JPO will make a decision on when it will lift the grounding and restart F-35B flight operations. "Determining the root cause and potential mitigating actions have the highest priority of the F-35B team," the JPO says. "Impact to SDD [system development and demonstration] execution and flight training operations is being assessed," the JPO says.
Static ground operations of F-35B STOVL aircraft will continue, the JPO says.