Pentagon Says More F-35 Fuel Tubes May Need to Be Replaced

Two more fuel tubes in F-35 jets may need to be replaced, according to the Pentagon, potentially adding to costs and disruption after a temporary grounding of the fleet.

It expands the suspect parts beyond an initial fuel supply line that may have contributed to the Sept. 28 crash of a Marine Corps F-35 and forced a brief grounding this month of the growing fleet. The fuel lines are part of the plane’s propulsion system provided by United Technologies Corp.’s Pratt & Whitney unit.

“In addition to the previously identified failed tube, analysis has identified two additional fuel supply tubes that require inspection,” Joe DellaVedova, spokesman for the Defense Department’s F-35 program office, said in a statement. He declined to say how many planes will need to be inspected.

The tubes provide fuel to the combustor and operating pressure to the engine for the fighter that’s built by Lockheed Martin Corp.

While the two additional fuel tubes haven’t failed, “engineering data collected during the ongoing investigation established the requirement for a time-phased inspection based on engine flight hours,” DellaVedova said. “Older engines may require fuel tube replacement. The procedure to inspect and replace can be done by flight-line maintenance without removing the engine.”

Operations Continue

F-35 operations continue on all aircraft with engines that haven’t reached the inspection requirements, according to DellaVedova. Earlier this month, the F-35 program office had said the initial failed part represented “an isolated incident which is quickly being addressed and fixed.”

About 320 of more than 3,000 planned F-35s for the Air Force, Navy, Marines and U.S. allies have been delivered so far.

The need to inspect more fuel lines raises questions not only about the durability of the parts supplied but also about the maintenance burden on military personnel. The F-35’s long-term support challenges are now the primary focus of senior defense officials who are concerned about independent Pentagon estimates that program support will cost about $1.1 trillion through 2077.

Next month, the F-35 is scheduled to begin congressionally mandated combat testing to assess its effectiveness against threats and its ease of maintenance.

Pratt & Whitney is “fully responsible” for the propulsion system and “has the lead in working the analysis,” DellaVedova said. Calculating the cost of the grounding, inspections and replacement of fuel tubes “will be addressed at a later time following completion of the investigation and upon completion of any required maintenance,” he said.

Pratt spokesman John Thomas said in an email that the company had no comment beyond the Pentagon statement.