Fairchild Industries' stockholders yesterday approved an increase in the number of shares of preferred stock and an issuance of new debt securities at a special shareholders meeting.

The aerospace company, based in Chantilly, has undergone a major restructuring in the wake of the cancellation of a government contract to make the T46 jet trainer for the Air Force. To fund its restructuring, Fairchild announced in July that it had received $34.2 million from New York investors George Soros and Harvey L. Karp in exchange for stock and debt. Yesterday, shareholders approved that swap.

Karp has been on Fairchild's board for more than one year, while Soros was recently elected to the board. Soros, described by Wall Street analysts as a sharp strategist, rarely serves on company boards but yesterday said he was "urged to do it" by Fairchild chairman Emanual Fthenakis and others.

Soros is the principal investment adviser for the Quantum Fund, an investment fund based in the Netherlands Antilles that owns 11.4 percent of Fairchild's stock. The total amount of the voting shares of the company's common and preferred stock now controlled by the Quantum Fund, Soros and Karp stands at about 22 percent.

In April, Soros abandoned his option to buy up to 49.9 percent of the company's stock. At the time, sources close to Fairchild said a substantial increase in stock ownership by the foreign-based fund could impair the company's ability to obtain clearances for government work. Under the present arrangement, the combined holdings of Quantum Fund, Soros and Karp will be limited to 24.9 percent for five years.

Soros said yesterday he had no plans to take over the company and increased his holdings for investment purposes only. "I have very much confidence in management and think they are on the right course," he said.

Fairchild, which has lost $177 million in the last two years, posted a net profit of $22 million in the first six months of this year. The company has agreed to sell for about $75 million its commercial aircraft division and a group of businesses that make a variety of products used in construction and manufacturing.

In a separate announcement yesterday, Fairchild said it will sell its Farmingdale, Long Island, plant where the T46 was built and 89 acres of land to an organization headed by Wilbur F. Breslin, a New York real estate developer. The selling price was more than $40 million, according to Fairchild.

The company estimates it will raise another $75 million from selling some remaining businesses, including a manufacturer of computer modems, an assembler of telecommunications systems for industrial parks and buildings, an aircraft financing company, a maker of industrial controls and a producer of computer cabinets. The company has also improved its balance sheet by repaying $52 million of high-interest debt and repurchasing about $16 million of preferred stock.

Fthenakis said yesterday the company will concentrate on the remaining businesses that make, among other things, aerospace fasteners, spacecraft systems and subsystems, aviation electronics and fluid and environmental control systems. "We are going to try to grow internally in those areas, and if there are opportunities we will go outside" and buy what makes sense, he said