A problem with the fueldraulics line behind the grounding of Marine Corps F-35Bs was likely caused by a quality issue in the manufacturing process that does not pose any design flaws or maintenance issues, the Pentagon said yesterday.
The inquiry by government and industry engineering teams concluded there was a quality discrepancy from the company that produces the parts and the faulty lines have been identified, removed from the aircraft and will be replaced, said Joe DellaVedova, the spokesman for the Pentagon’s F-35 Joint Program Office.
“The F-35 Joint Program Office and Naval Air Systems Command are developing a return to flight plan which details the removal and inspection requirements of currently installed fueldraulic lines on the 25 F-35B variants affected by the flight suspension,” DellaVedova said.
The Pentagon earlier this month suspended flight operation of the Marine Corps variant of the Joint Strike Fighter following an incident involving a fueldraulic line in the vectoring propulsion system of the short take-off and vertical landing-aircraft (STOVL) (Defense Daily, Jan. 23, 2012).
The line is unique to the F-35B, meaning the Air Force F-35As and Navy F-35Cs were unaffected. DellaVedova said the lines were improperly crimped.
The Jan. 18 grounding was prompted by an aborted flight two days earlier at Eglin AFB, Fla., where an F-35B experienced a fueldraulic line failure while initiating a conventional takeoff roll. Faulty parts were found on an additional six aircraft, DellaVedova said.
F-35Bs at Marine Corps Air Station Yuma, Ariz., and at manufacturer Lockheed Martin’s facility in Fort Worth, Texas, are also under flight suspension.
Pratt & Whitney, a subsidiary of United Technologies [UTX] along with partner Rolls-Royce, provide the propulsion systems for the F-35Bs. The fueldraulic lines are supplied by Stratoflex, a division of Parker Hannifin [PH].
“We have begun the process of removing the suspect fueldraulics tubes from the STOVL aircraft, and we are performing additional X-Ray imaging inspections on the tubes in order to ensure their integrity,” said Matthew Bates, a spokesman for Pratt & Whitney.
Instead of traditional hydraulic fluid, the part instead uses fuel as the operating fluid to reduce weight, DellaVedova said. Rolls-Royce and Pratt & Whitney have taken steps to improve their quality control processes in light of the incident, DellaVedova said.
Bates said Pratt & Whitney expected flights to resume soon.