The F-35 Joint Program Office issued a precautionary suspension of flight operations today (Friday — 18 Jan) for development and test F-35B Short Takeoff and Vertical Landing (STOVL) variants. A similar action was taken by Naval Air Systems Command for all F-35B production aircraft operating at Eglin Air Force Base, Fla.; Marine Corps Air Station Yuma, Ariz.; and at Lockheed Martin’s production facility in Fort Worth, Texas.

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. The line enables actuator movement for the STOVL vectoring exhaust system.

Static ground operations of F-35B STOVL aircraft will continue. Flight operations for F-35A or F-35C model aircraft are unaffected.

The event occurred Jan. 16, at approximately 10 a.m. CST. While initiating a conventional mode takeoff roll, the aircraft experienced a propulsion system fueldraulic failure prior to takeoff. 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.
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Government and contractor engineering teams are reviewing data from the event to determine the root cause of the failure. Implementing a precautionary suspension of flight operations is a prudent response until F-35B engineering, technical and system safety teams fully understand the cause of the failure. Safety of pilots and ground crew is the top priority of the program.

Once the causal and contributing factors are understood, a determination will be made when to lift the suspension and reinstate F-35B flight operations. Determining the root cause and potential mitigating actions have the highest priority of the F-35B team. Impact to testing and flight training operations is being assessed.

Periodic updates concerning this situation will be released as warranted.