Federal Aviation officials have received information alledging that at least three U.S. helicopter crashes in the last two years - one of them fatal - involved a failure in flight of bogus parts.

According to industry sources the parts were carrying the identification of the Bell Helicopter Co., a major U.S. manufacturer. But the sources said a recent investigation by Bell showed the parts were not manufactured by the company and that there was no way to determine whether they met Bell engineering standards.

According to National Transportation Safety Board records one of the crashes Bell refers to took place in Napa, Calif., in July of 1975 and killed the pilot of the aircraft. Two other persons - a pilot and a student pilot - were seriously hurt in a crash in Nashville, Tenn., in May, 1975. No injuries were reported in a third crash at Pigeon Forge, Tenn., in August, 1975.

The safety board in January, 1976, issued a safety recommendation noting that all the crashes involved the failure in flight of a critical part known as a tail rotor hub assembly bolt. The Bell helicopters involved all were Model 47s - light, bubble-topped two-seaters.

The board report made no mention of bogus parts although the Bell Helicopter Co. issued service bulletins to the owners of its aircraft after the crashes ordering the bolts removed and replaced. The replacement parts, according to the company warning, should have been verified Bell parts.

Industry sources said Bell investigators positively identified the parts the federal agency said had failed as bogus. Bell is being sued by persons involved in each of the accidents.

The safety board said that out of approximately 300 non-military crashes that occur each year in the United States, Bell Model 47 helicopters account for about 100 to 125.

The NTSB said a crash was defined as an accident involving a serious injury or major damage to an aircraft.

The Aerospace Industry group in Washington, said about 850 Bell Model 47s are operating in the United States, comprising about 17 per cent of the total non-military helicopter fleet.

The NTSB records indicate that since 1974 there have been 21 Bell 47 helicopters crashes in the United States that have involved failure of tail rotor parts.

In February, The Washington Post reported that millions of dollars in alleged bogus Bell and Sikorsky Aircraft helicopter parts were being made in the United States without proper engineering information and sold in this country and abroad by the Aviation Sales Corp., a New York City firm.

A Bell official said today that his company was not able to determine whether the allegedly bogus parts involved in the three helicopter crashes came from Aviation Sales.

Bell turned over the results of its investigation last week to the Federal Aviation Administration's district office in Fort Worth, Tex.

The FAA requested the Bell information after the company filed a $35 million lawsuit April 12 against Aviation Sales and eight other companies and two indivduals charging them with manufacturing and selling bogus helicopter parts under the Bell name.

The FAA and the U.S. Attorney's office in Los Angeles, where some of the bogus parts were allegedly manufactured, are both conducting investigations of the alleged bogus parts scheme.

The U.S. Attorney's office here said this week that federal investigators will take their findings before a federal grand jury in Los Angeles within a month.

Sources have told The Washington Post that much of the allegedly bogus material was sent by Aviation Sales to England for use by the British military or by military helicopter fleets in a number of other countries.

A spokesman for Westland Helicopters for the British army, told The Post in February that bogus parts may have been installed on as many as 200 light helicopters flown by the British army.

A British Defense Ministry spokesman said at that time that "none of these components affect flight safety."

However, documents filed in federal court here in connection with the $35 million Bell lawsuit this month indicate the Defense Ministry spokesman's assurances may not be correct.

In a sworn affidavit filed in U.S. District Court in Los Angeles, J. M. Gooch, Bell's manager of product assurance, said that in February he inspected parts shipped by Aviation Sales to Westland in Teoville, England.

Gooch said he discovered that 90 per cent of the parts he examined were bogus. "I am of the opinion that these bogus parts may pose a substantial and significant threat to the lives of passengers and crews who are in helicopters which have incorporated these parts," Gooch said in his affidavit.

A Bell Helicopter official said recently that Gooch did not find any tail rotor hub assembly bolts during his inspection of the allegedly bogus parts.

Aviation Sales officials in New York referred all questions to the company's Los Angeles attorney, Martin Sturman. Sturman said Aviation Sales has not entered a formal response yet to the Bell lawsuit. He declined to comment on Gooch's affidavit or the lawsuit.