FORT WORTH (CBSDFW.COM) – The majority of the employees on strike at Lockheed Martin in Fort Worth work on the F-35 Joint Strike Fighter.

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Orders for the aircraft, from the Pentagon and several foreign countries, have been on hold. Mostly testing setbacks have caused the delays on the radar-evading fighter, but the strike isn’t helping.

“What we’re being told is there’s not much work going on at all, very little, that most of the factory is actually dark and the lights are off,” said Paul Black, president of the Association of Machinists and Aerospace Workers Local 776.

Officials with Lockheed say the plant is open and operating.

Black and other union leaders say the men and women on the line have been instrumental in the F-35’s development.

“This program has been a little different than past programs, where it’s kinda like a learn-as-you-go kinda thing,” Black said. “They’ve [line workers] worked out a lot of the bugs in the program.”

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As the delays continue projected costs, initially set at $113 million per plane, also continue to rise.

Black says the contribution of the more than 3,000 Fort Worth employees now on the picket line is invaluable.

“They’ve worked out a lot of the bugs in the program,” Black said. “They’re actually out there on the production floor and our guys have been a very big part of that. Ya know, finding the solutions to some of the problems and helping get it [F-35] on the right track.”

Workers are striking over Lockheed’s proposal to pass on more health care costs to employees and to do away with pensions for new hires.

“The membership they have the right to vote on the contract and they turned it down and then they have a right to strike…withhold their labor,” Black said. “That’s the only recourse.”

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Lockheed employees in Fort Worth have been on the picket line for more than a week.