A Northern Virginia builder is asking Fairfax County for permission to construct a major commercial project west of the Dulles airport road, traditionally the boundary between Tysons Corner-style development and residential areas farther west.

Dwight Schar, chairman of the board of Northern Virginia Land Inc., and of NVHomes, has hired former Virginia attorney general J. Marshall Coleman and brought in the dean of the school of architecture at the University of Virginia to press his case, which will require a change in the county's comprehensive land use plan. Schar is seeking to have 98 acres west of the Dulles airport road and north of the Leesburg Pike redesignated from residential to commercial.

The Dulles road has long been a "line of demarcation" against expansion of commercial development westward beyond the Dulles interchange along the heavily congested Leesburg Pike corridor. The site is bounded by the Dulles road, Lewinsville Road and the pike. It is close to some of McLean's most expensive neighborhoods, including Summerwood, where houses range from $400,000 to $750,000.

The request is expected to generate considerable opposition.

Fairfax County Planning Commission chairman George Lilly said the project will draw attention from many who were quiet about the Tysons II proposal because that was for a site that was already zoned commercial and was in the center of the heavily developed Tysons Corner area.

In the application to change the master plan for the site, the largest remaining residentially zoned tract in the Tysons area, Coleman called the property "unsuitable for residential development . . . ." Coleman said the opening of the Dulles toll lanes detracted from the site's residential potential.

"The toll road's main toll plaza lies less than 500 feet to the east of the site," Coleman said.

But some county officials said they see the application as an attempt to expand the Tysons Corner commercial area.

"I had told them the developers I could not support the expansion of the Tysons Corner area," Fairfax Supervisor Nancy Falck said. The property is in the Dranesville district which she represents. "I don't think they can get anything but residential. And I am holding to that," Falck said. She said she supports maintaining the Dulles road as the dividing line between commercial and residential development.

The application said that Lewinsville Road, not the Dulles road, should be the barrier between the two types of development.

"The McLean Citizens Association is loud and clear on this," said Stephen Hubbard, chairman of that group's planning and zoning committee. "The D.A.R. Dulles airport road is it. It has been recognized as the boundary."

Coleman said "we took it to the experts," who said commercial use was best for the site. Coleman was referring to Jaquelin T. Robertson and Christopher J. Glaister, partners in Design Development Resources, an architectural and planning firm with offices in New York and Charlottesville. Robertson is dean of the school of architecture at the University of Virginia.

The result was a plan for the site, which now includes several farms, that is completely commercial but, Schar said, leaves 60 percent of the 98 acres in open space. Schar said he is in the preliminary stages of working out transportation access along the pike.

Coleman, now an attorney in private practice, said the plan offers a way to make sure the site is "not developed piecemeal in a manner that takes away from the residential character of the neighborhood." He said the attempt to change the status of the site is an effort to correct "an error in the plan" itself.

"Numerous rezonings and special exceptions granted in recent years have pushed back the perimeters of Tysons Corner and increased the height and density of development in the Tysons areas," according to the application.

The appplication is only the first step toward getting approval for actual commercial construction. If the plan is changed, Schar would have to submit a rezoning application to get a specific plan approved.

No details were available as to size or height of structures planned.