Flight restrictions on Lockheed Martin Corp. (LMT)’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. […]