Flight restrictions on Lockheed Martin Corp.’s F-35 are hampering the Pentagon’s ability to conduct the software tests the plane must pass before it can be declared combat-ready by next July, according to the Pentagon’s weapons-testing office.
The start of rigorous in-flight testing on the initial software for the Marine Corps version of the fighter is already five months late, and may be further delayed by the flight restrictions imposed on the 20 test aircraft and 79 training jets after an engine fire on an Air Force F-35 on June 23.
“Many test points remain blocked or difficult to achieve because” of the flight restrictions, Jennifer Elzea, a spokeswoman for Pentagon director of operational testing Michael Gilmore, said in an e-mailed statement. “This may cause further delays in completing” testing of the software, she said.
The Defense Department initially grounded the entire fleet of 99 F-35s made by Bethesda, Maryland-based Lockheed after a fire in a plane at Eglin Air Force Base in Florida forced the pilot to abort a takeoff.
The directive was later eased to imposing a limit on airspeed and requiring an inspection of the engines, made by United Technologies Corp.’s Pratt & Whitney unit, after every three hours of flight. Last week, that was further relaxed to permit test aircraft to fly six hours between engine inspections when evaluating aerial refueling and weapons delivery capabilities, Elzea said.
The progress of the Marine Corps version, the most complex of the three models in the $398.6 billion program, has drawn international attention. The U.K. and Italy have committed to buying the version, the F-35B, which is designed for short takeoffs and vertical landings on fields and aircraft carriers.
Software is crucial to delivering the promised capabilities of the F-35 and operating its navigation, communications and targeting systems. Each plane will have more than 8 million lines of code once deployed, more than any previous U.S. or allied jet.
The software for the Marine version of the F-35, known as 2B, is undergoing verification on test aircraft to confirm that it meets contract specifications. The second phase of more rigorous software testing has been scheduled to start in October, five months later than planned, according to a June 17 Pentagon software review that was required by Congress.
The F-35 grounding and the restrictions imposed after the crash may delay completion of the verification testing and the start of the second phase, according to the Pentagon test office.
The latest version of 2B software started verification testing a few weeks before the engine fire, so “not enough has been learned about this version to be certain of the extent” to which its capabilities have improved, Elzea said.
“There are also numerous, well-documented deficiencies identified from testing of earlier versions of Block 2B that are either partially resolved or unresolved in the latest version of Block 2B software,” Elzea said.
Joe DellaVedova, spokesman for the Pentagon’s F-35 program office, didn’t provide a comment on how the flight restrictions may affect software testing.
DellaVedova said in a statement last month that since 2011 the program office “has undertaken an overhaul of the management and direction of the F-35 software development effort.”
“We have instituted a rigorous systems engineering process that develops build plans for each major air system component and tracks incremental capability maturity within each software block,” he said.
Deputy spokeswoman Kyra Hawn said in an e-mailed statement that the public can expect updated information about software testing from the program office next month, possibly at the annual Air Force Association conference in Washington’s Maryland suburbs.
Lockheed Martin spokeswoman Laura Siebert said in an e-mailed statement that the company continues to work with the program office “to determine the impact on F-35 flight test due to the recent grounding and current flight limitations.”
“The development schedule has margins built in to allow for discoveries and occurrences like these, and we remain confident that we will complete 2B software to support Marine Corps” initial combat capabilities in July, she said.
Matthew Bates, a spokesman for the Pratt & Whitney unit of Hartford, Connecticut-based United Technologies, said in an e-mail that the company “is working closely with the” F-35 program office and Lockheed “to clear remaining test points to achieve 2B fleet release on time.”