Pentagon Examining Fueldraulic Line Failure On F-35B

The Pentagon has suspended flight operations of the Marine Corps variant of the F-35 Joint Strike Fighter (JSF) as a precaution following an incident involving a fueldraulic line in the vectoring propulsion system, a spokesman said.

Joe DellaVedova, the spokesman for the F-35 program office, said recently the Pentagon is still looking into the problem behind the grounding that took effect.

“We’re still driving to root cause,” he said in an email.

The grounding affects 25 F-35Bs, which are designed for short-takeoff and vertical-landing (STOVL), located at Eglin AFB, Fla., Marine Corps Air Station Yuma, Ariz. and at manufacturer Lockheed Martin’s facility in Fort Worth, Texas, he said. It does not impact operations of the Air Force’s F-35A or Navy’s F-35C.

“The precautionary flight suspension preserves safety while providing time for the program to understand the origin of a failure of a propulsion fueldraulic line,” he said. “The line enables actuator movement for the STOVL vectoring exhaust system.”

The incident that prompted the suspension took place Jan. 16, when an F-35B experienced a fueldraulic failure while initiating a convention takeoff roll. The pilot aborted the takeoff.

“Government and contractor engineering teams are reviewing data from the event to determine the root cause of the failure,” DellaVedova said. “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.”

“Once the causal and contributing factors are understood, a determination will be made when to lift the suspension and reinstate F-35B flight operations,” he said.

A spokesman for Pratt & Whitney, which provides the propulsion systems for F-35s, said the fueldraulic lines are supplied by a subcontractor, and that the company was working with partner Rolls-Royce, as well as Lockheed Martin and the Pentagon, to examine the problem.

“An initial inspection discovered a detached fueldraulic line in the aft portion of the engine compartment near the bearing swivel module,” Matthew Bates said.