American businessman Francis J. Crawford, convicted Thursday of black market currency dealings, flew out of the Soviet Union last night on his way to the United States after obtaining a quick exit visa from the ministry of Foreign Trade.

Accompanied by his fiance, U.S. Embassy secretary Virginia Olbrish, and his two American attorneys, Crawford said that he intended to return to the Soviet Union in about four weeks to visit his fiance, who will have returned by then.

Shortly after he left on a Lufthansa flight to Frankfurt, however, the official Soviet news agency Tass said that Crawford had been "expelled." Crawford had spent part of the day filling out his accreditation papers at the request of the Trade Ministry so he would be assured permission to re-enter the Soviet Union.

"I would like to come back. I would not like to think that I am barred from the Soviet Union. There's no indication on my visa that I cannot return," Crawford said before he passed through the final customs point.

Crawford, 37-year-old products manager for the Moscow office of International Harvester Co., had originally been told by the ministry that his exit visa would take at least five working days to process. Resident American businessmen here must apply for permission from the Soviet passport office each time they enter or leave the country.

With his bags packed and wearing his ever-present cowboy boots, the stocky businessman joked and chatted with reporters at Sheremetyevo Airport before boarding the aircraft. With him and Olbrish were Robert Booth, assistant general counsel of Harvester, and Peter Maggs, a University of Illinois law professor and specialist in Soviet law who was retained by Harvester to help prepare Crawford's defense.

After a two-day trial, Crawford was convicted and sentenced to five years' suspended sentence in a Soviet labor camp. He immediately applied for an exit visa.

According to Tass, Crawford's boss here, John Challman, resident director of Harvester in the Soviet Union, was called to the protocol department of the Trade Ministry and "told Crawford must immediately leave the Soviet Union. On the same day, Crawford was expelled from the U.S.S.R."

The Soviet judge that sentenced Crawford said he had seven days to appeal the conviction to a higher court, but Crawford said that the appeal could be handled by his Soviet attorney without his presence in Moscow. He said International Harvester officials in Chicago would decide over the weekend whether to appeal.

Born in Maryland, Crawford calls Mobile, Ala., his home. He said he will go to Chicago "to discuss future plans" with his company and then to mobile for a vacation. He owns a far in the Mt. Airiy area of Maryland.

Olbrish said Thursday that she will return soon to her duties at the embassy here, where her assignment runs in to next year.

Crawford's departure brings to an end a three-month episode that began when he was arrested June 12 by Moscow police and dragged off to Lefortovo Prison. He was incarcerated for 15 days until the U.S. governmentarranged his pretrial release in return for the similar release of two accused Soviet spies in New Jersey, Rudolf Chernyayev and Valdik Enger. Crawford's arrest was believed by many here in the foreign community to have been Soviet retaliation for the arrest of the two Soviets.

Chernyayev and Enger are now scheduled for trial in New Jersey Sept.27.