The defense budget approved by Congress eliminates 20 of the A10 warplanes that the Air Force planned to order as the final part of its contract with Fairchild Industries Inc.

The action, approved Tuesday by the Senate and by the House Wednesday, means government orders for the twin-engine, antitank jet, which goes through final assembly and flight testing at Fairchild's plant here, will run out next year, one year earlier than anticipated.

The order would have been worth more than $360 million.

Theron Rinehart, a spokesman at Fairchild's plant here, said the firm was disappointed at the cut.

"Since the Air Force has given the A10 a 'fully mission capable' rating of 77.1 percent and an accident rate of 5.6 aircraft per 100,000 flying hours -- one of the lowest accident ratings in the history of Air Force aircraft -- we can understand the Air Force may need fewer than they originally thought," Rinehard said. In essence, fewer planes go out of service, so not as many are needed.

But, he added, "We are disappointed at the threatened premature closing of the only dedicated close-air-support-aircraft production line at a time when the true value of the A10 is being realized, and defense studies indicate that the tank threat is increasing."

Air Force spokesman Lt. Col. Bob Nicholson suggested that the A10 cut came because "first, there are higher fighter priorities at this time, and, second, buying planes at the rate of 20 per year is not a very efficient way of doing things."

Rinehart said company officials would not speculate on how Congress' action would affect employment at the western Maryland plant, where 2,500 people work. Subassembly work on the A10 is done at Fairchild's Farmingdale, N.Y., plant, which employs 5,000. Fairchild is an aerospace manufacturing company based in Germantown, Md.

Rinehart said there is a possibility that Fairchild, which has delivered 640 A10s to the Air Force since 1975, may keep the A10 production line open as it looks for foreign buyers of the antitank aircraft.

A Fairchild spokesman said "a foreign buyer would be needed in the next six to nine months" to offset the impact on the A10 production line, and no foreign buyers have been found yet.