Loudoun County business executives petitioned the Board of Supervisors last week to repeal the county personal property tax on aircraft, claiming that the tax discourages economic development at Dulles International and Leesburg Municipal airports.

"Aircraft based at National Airport or anywhere in Maryland or West Virginia pay no personal property tax," said Kathleen Bocek, chairman of the Loudoun Chamber of Commerce legislative committee. "The county promotes Dulles as an economic center but the tax puts Loudoun at a competitive disadvantage."

Although it brings in relatively little county revenue--$135,000 for 1983--Bocek said the tax is the reason there are no major corporate aircraft, commuter or charter planes based in Loudoun County. Bocek said many Loudoun residents keep their personal planes at airports in Frederick, Md., and Martinsville, W. Va., to avoid the tax.

Jim Haynes, president of Janelle Aviation, the fixed base operator at Leesburg Municipal Airport, said he knows of two specific cases where operators of corporate planes have chosen to move their aircraft to National Airport to avoid the county tax, but he was unwilling to name the companies. He said one had had a $13 million plane at Dulles that was taxed $195,000 a year by the county in the past.

The county tax rate on aircraft is $1.50 per $100 of assessed value for planes based in the county on Jan. 1. For an inexpensive single-engine airplane, that tax would be less than $100 a year. But for a $25 million plane, such as a Boeing 727, said Haynes, the tax would be $375,000.

"Anytime you have an increase in the cost of doing business, it proves to be a disincentive," said Don McGuire, vice president for public affairs for Piedmont Airlines. McGuire said Piedmont considered using Dulles for some Washington area flights, but settled on Baltimore-Washington International Airport in Howard County, Md.

"We had a superior offer from BWI," said McGuire. "There wasn't just one factor in the decision."

For the Loudoun Chamber of Commerce, stories of airlines bypassing Dulles raise concerns over whether the airport will ever attract the air traffic Loudoun businesses hope for.

"The point we are trying to make is that, while the revenue the county brings in from this tax is quite small, the tax works as a large disincentive," said Haynes. "In a few weeks, we expect to have a study done that will show how much other county revenue could be collected from sales and business license taxes if a major airline decided to establish a hub at Dulles. It would far outweigh the tax."

The Chamber has been supported in its efforts by the Washington Dulles Task Force. Thomas G. Morr, president of the task force, said that lifting the personal property tax on aircraft was just one of several things that could be done to make Dulles more attractive to air carriers.

"I do not know of any airline to date that has decided against Dulles for that reason alone," said Morr. "But I do know that they are concerned about anything that adds to their operating costs."

The Loudoun County Board of Supervisors, however, did not appear receptive to the idea when Bocek spoke at their meeting last week.

"I was very disappointed," said Bocek. "They didn't comment or anything."

For the board, whose eight members are up for reelection this fall, it may be difficult to repeal a tax that only hurts those wealthy enough to own a private plane.

But Haynes said he is optimistic: "I think we can show that repealing this tax would bring more money into the county, and that may interest them."