A federal grand jury indicted a flamboyant former Washington businessman, Bruce Parkyn Jackson, here yesterday on a variety of charges alleging that he concocted an elaborate loan scheme in which he diverted $300,000 of borrowers' money to his own use.

Jackson, who four years ago was on top of the international business world and maintained a yacht on a French canal and a Rolls-Royce, was charged with 10 counts of wire fraud, five counts of interstate transportation of property taken by fraud and four counts of making false pretenses. If convicted on all 19 charges, Jackson faces up to 112 yheas in prison and a $60,000 fine.

Assistant U.S. Attorney Brian W. Shaughnessy said Jackson, 37, is living in Switzerland. The prosecutor said he plans to send Jackson a letter informing him of his indictment and thinks that he may return voluntarily.

At one point in 1976, as angry creditors searched Europe for Jackson, he hid in a tent high in the snowy Pyrenees Mountains and stalked wild pigs and ate dandelions. He later returned to Washington for a while saying that he wanted to assist some of the Businesses that lost money in dealing with him. He also opened a gallery displaying some of his own paintings.

The indictment alleges that Jackson defrauded various persons and companies that were in financial difficulty by promising to pay their bills by giving them one-month loans at high interest rates. The indictment charged that Jackson often would delay or stop payment on the checks to the borrowers' creditors and divert the loan payments to his own use. $,,creditors and divert the loan payments to his own use.