HARRISON, N.Y. (AP) _ Cessna Aircraft Co., the well-known builder of small airplanes, expanded Tuesday into the ``fractional ownership'' market, a kind of time-share business for corporate jets.

The move is the latest sign of a trend that has resulted in record sales of business jets and has allowed about 1,500 companies to claim part-ownership of a plane.

Cessna, part of the Textron conglomerate, announced it is buying 50 percent of TAG StarShares Holding, a subsidiary of TAG Aviation USA Inc. Terms were not disclosed.

StarShares is being renamed CitationShares Holding. It will be headed by Steve O'Neill, StarShares' chief executive officer. Neil Armstrong, the first man on the moon, will be chairman of the board.

The new venture, based at Westchester County Airport in Harrison and concentrating on the eastern United States, will operate a small fleet of Cessna's Citation jet aircraft for the fractional market, in which businesses typically pay much less for access to a jet than they would pay for full ownership.

Cessna spokeswoman Tish Cohlmia said a business that buys a share would call when it needs a plane and would typically be able to fly within half a day. The larger the share, the more hours of flying time available to the business.

An eighth of a share in one of Cessna's six-seat Citation Bravos, for example, would cost about $700,000 and guarantee 100 hours of flight time on any plane in the fleet.

CitationShares would provide the plane, the pilot and aircraft maintenance. It would feature Citation's new CJ1 and Bravo models, the company said.

Roger McMullin, TAG's chief executive officer, said CitationShares would combine Cessna's product line and marketing with TAG's experience in aircraft operations. Gary Hay, Cessna's CEO, said the new company would have ``the lowest entry price for new jet aircraft in the fractional ownership market.''

Cessna already sells planes to other firms that market time-shared jets, including industry leader Executive Jet Inc., which says it has bought 45 percent of all the business jets ordered in the past four years.

Cohlmia said the new company would not be in direct competition with Executive Jet because that company specializes in larger jets.

Other manufacturers, including Raytheon Aircraft Co. and Bombardier Aerospace, already operate fractional jet programs.