Lockheed Martin Corp Chief Executive Marillyn Hewson said the company's F-35 Joint Strike Fighter program was progressing "very well" and she expected to finalize agreements for sixth and seventh production orders with the Pentagon in the first half of 2013.

Hewson said the F-35 fighter uses similar lithium-ion batteries as those being investigated on Boeing Co's 787 Dreamliner, but they were made by a different manufacturer and had been tested and vetted extensively.

She said investigators were still trying to determine what caused a problem that prompted the Pentagon to ground the U.S. Marine Corps variant of the F-35 last week.

(Reporting By Andrea Shalal-Esa; Editing by Maureen Bavdek)