Fairfax County Republican supervisors, who assumed control of the county board last November, are planning what some Democrats fear may be major changes on many of the county's boards and commissions.

"The door has not been open in the past to very qualified Republicans," said GOP Supervisor T. Farrell Egge. He said the county board's five-member Republican majority may seek replacements for many longtime Democratic appointees.

In a vote scheduled April 29, the Republicans are planning to replace two Democratic appointees to the county's Economic Development Authority with their own nominees, a move that has angered the county's four Democratic supervisors.

Egge, who has vowed to appoint more Republicans to county positions and who two weeks ago tried unsuccessfully to remove a Democratic appointee from a county board, has asked the supervisors to name his campaign finance chairman, Frank J. Quirk, to the authority.

County Board Chairman John F. Herrity, a Republican, said he plans to nominate E. Donald Stack, a public relations executive with American Telephone and Telegraph Corp., for the other seat on the seven-member EDA commission. It oversees efforts to lure new business to Fairfax.

Herrity said that the GOP is not seeking to dominate the EDA. "This is not some Republican operation," he said.

Democratic supervisors -- accustomed to controlling the appointments -- argue that the GOP tactics are a crass break with tradition, replacing appointees who are considered to be doing a good job.

Two Democratic supervisors have renominated incumbent EDA commissioners John E. Lynch and Betti Goldwasser.

Lynch, a senior Pentagon budget official, is a longtime member of the EDA.

Goldwasser, currently vice chairman of the EDA, is the only commissioner who is not a white male, and is considered to be a liberal.

"I really hate seeing them make a political football out of EDA," said Democratic Supervisor Martha V. Pennino, the county board's vice chairman.

"But if the Republicans have five votes on the nine-member board ," she added, "then that's the name of the game."

"It may be a signal that there will be a lot of purely partisan appointments to at-large appointments," said Democratic Supervisor James M. Scott.

Pennino called the GOP move to unseat the two incumbents "very unusual. We're not like Chicago or Philadelphia where there's constant turmoil on the elected body."

Several Democrats in Fairfax also said that Quirk, Egge's nominee to the EDA, lacked basic qualifications for the position.

Quirk, 44, is head of a management consulting firm in Silver Spring, and has not been active in Fairfax civic affairs.

"The EDA is basically marketing Fairfax County," said Suzanne H. Paciulli, a former president of the Fairfax County Chamber of Commerce. "The commissioners really ought to be from the Fairfax business community."

Paciulli said that she believed it would be "awkward" for Quirk, a Maryland businessman, to sell Fairfax to prospective businesses seeking to locate in the metropolitan area. "I'd ask, 'Well, gee, if it's so great [in Fairfax] why aren't you over there?'"

Egge said Quirk will "bring a perspective that we haven't seen before" to the EDA.

Quirk is "an extremely competent businessman with very good insights," said Egge. "Who better than a successful businessman for the EDA?"

The Chamber of Commerce has endorsed Lynch and Stack for the two EDA seats, which carry four-year terms and pay members $25 for each monthly EDA meeting they attend.