About Lockheed Martin [LMT] 500 employees at the company’s aerospace plant in Fort Worth, Texas, represented by two separate unions ratified new labor agreements with the company last week .

The agreements with the International Brotherhood of Electrical Workers (IBEW) and the Office and Professional Employees International Union (OPEIU) went into effect yesterday and will extend for four and five years, respectively, Lockheed Martin said. The union employees support the F-35, F-16 and other programs.

However, terms of a new labor agreement involving a larger contingent of aerospace workers remain unresolved. The workers, represented by the International Association of Machinists and Aerospace Workers (IAM), have been on strike since April 23.

Lockheed Martin said on Saturday that the new contracts with the IBEW and OPEIU include a defined contribution plan for new hires instead of a defined benefit pension plan. The company said these terms are similar to those offered to the striking employees represented by the IAM at Fort Worth, Naval Air Station Patuxent, Md., and Edwards AFB, Calif.