Engineers at Wolf Trap's Filene Center, where a gaping 8-foot crack was discovered Thursday in one of four giant steel girders supporting the roof, said yesterday it is unlikely the beam will sustain further damage.

"It's a much more stable situation than you might intuitively think when you see that big crack," said A. Russell Versaci, project manager for Dewberry & Davis, the Fairfax County firm that designed the new center.

Another engineer added, however, "If we should get a two-foot snowfall, I'd be worried."

Officials at Wolf Trap, the country's first national park for the performing arts, said they expect the damage to be repaired in time for the scheduled opening of the 1985 season on June 8. But Morgen Rasmussen, a spokesman for the Wolf Trap Foundation, which handles programming for the Filene Center, acknowledged that the facility may face a problem in convincing patrons the building is sound.

"We will have a season in 1985," he said, but added that public relations "is an issue."

Catherine Filene Shouse, the heiress who donated 100 acres and $2.3 million to build the original auditorium, said yesterday: "I gave it to the people of this country . . . and I'm just sorry that it's had such difficulties."

Officials said yesterday that it will be weeks before tests determine the cause of the fissure, which splits the hollow beam vertically. They added that no repair work will begin until the cause is known, and said it is too early to predict the cost of the project.

Officials were vague about who will pay for the repair work, which they say could be extensive. Park officials said the center, which is insured by the government, is covered by a one-year warranty from the chief contractor, G&C Construction Co. of Fairfax, but declined to say that G&C would pay for repairs. G&C officials could not be reached for comment.

"We don't want to sit down and argue about who's going to pay for it right now," Versaci said.

Sandra Alley, a spokeswoman for the National Parks Service, which owns the park, said engineers plan to cut a hunk of steel from the beam and run it through metallurical tests to determine whether flaws in the steel caused the break.

She said Dewberry & Davis, the architectural firm, also will perform a structural analysis of the center.

"We won't allow people to go under it next summer unless it's safe," Alley said. "It's not something we can't fix."

Engineers said it is unlikely the beam will have to be replaced. Rather, they said the cracked beam -- and possibly the three other main roof girders -- will probably be reinforced in some fashion.

They said the severe cold last weekend was likely a contributing cause of the fissure, but they added that other factors, such as design and steel flaws, may also be at fault.