The Iranian government has cancelled a $575 million contract with Bell Helicopter to build a major helicopter production facility in that country, Textron Inc. announced yesterday.

Alluding to the civil unrest there, the Iranians said, "force majeure events" (overpowering acts) made it impossible to continue building the production facility, according to Textron, Bell Helicopter is a division of Textron.

Robert A. Seraphin, a Textron vice president, sought to minimize the effect on Bell's profits of the collapse of the Iranian deal.

"We still expect the Bell Helicopter is going to have a good year next year," he said. "And we are fairly secure with Bell's future even without this program."

It was a year ago next month that the circumstances surrounding this contract came under public scrutiny during Senate confirmation hearings on the nomination of then Textron Chairman G. William Miller as chairman of the Federal Reserve Board.

It was revealed during the hearings that Bell made a $2.9 million payment to a subsidiary called Air Taxi at the same time Bell was awarded the $575 million contract. It was further disclosed that Air Taxi was owned in part by the late Gen. Mohammed Khatemi, commander of the Iranian Air Force.

Miller, who had been chairman of Textron at the time, said he had no knowledge of the payments or the circumstances surrounding them. The Securities and Exchange Commission, Internal Revenue Service and the Justice Department are investigating the Air Taxi affair.

Bell accounts for 27 percent of the conglomerate's sales so far this year and 22 percent of its net income.