An “improperly crimped” fluid line was the probable cause of a propulsion-system leak that led the Pentagon to suspend flight tests of the F-35 fighter’s Marine Corps version, according to the Pentagon.
The investigation “ruled out any design or maintenance issues,” Pentagon spokesman Joe DellaVedova said yesterday in an e-mailed statement. The evidence revealed “a quality discrepancy” resulting in the crimped line, he said.
Test flights of the Marine version, the F-35B, were stopped after a pilot aborted a takeoff because of a flaw in the propulsion system made by the Pratt & Whitney unit of United Technologies Corp. The incident involved a line in the plane’s fueldraulic system, which saves weight by using jet fuel instead of the customary hydraulic fluid to lubricate mechanical parts.
The Jan. 18 flight suspension remains in effect, according to DellaVedova.
Development of the F-35 has been marked by delays and cost increases. The Pentagon’s $395.7 billion estimate for the total cost of development and production of 2,443 fighters is a 70 percent increase since the initial contract with Bethesda, Maryland-based Lockheed Martin Corp. was signed in 2001.
The Marine Corps’ F-35B is designed for short takeoffs and landings on carriers and amphibious-warfare vessels. It’s the most complex of three models being built in the Pentagon’s costliest program. The U.K. and the Italian military are also buying the F-35B.
An audit of quality control records has identified six additional “non-compliant units” that have been removed from aircraft and returned to Pratt & Whitney for replacement, DellaVedova said. The flawed part is only on the Marine Corps version.
“We have begun the process of removing the suspect” parts and “we are performing additional X-ray imaging inspections,” Matthew Bates, a spokeswoman for the Pratt & Whitney unit of Hartford, Connecticut-based United Technologies, said in a e-mail.
“The team continues to work diligently toward completing the investigation and implementing corrective actions with the supplier,” Bates said. “We anticipate a return to flight” soon.
The flawed fueldraulic line was made by Stratoflex Products Division, a unit of Cleveland-based Parker Hannifin Corp., according to the Pratt and Whitney statement.
The company “is fully supporting our customers during the investigation,” Cheryl Flohr, a Parker Hannifin spokeswoman, said in an e-mail. “Parker team members have been working alongside since the beginning of the situation.”
The companies “have instituted corrective actions to improve their quality control processes and ensure part integrity,” DellaVedova said.
The Pentagon’s inspector general has been investigating quality management for the F-35, including relevant clauses in contracts, since February 2012.
The review had identified more than 190 findings as of September as well as four “notices of concern” have been sent to the Pentagon’s F-35 program office, the inspector general said in its latest semi-annual report to Congress.