FOUR European aerospace companies have teamed up with their great United States rival Boeing to embark on a year-long study examining the feasibility of developing a new extraordinarily large passenger plane. The European aircraft manufacturers taking part are France's Aerospatiale, British Aerospace, CASA of Spain and Germany's Deutsche Aerospace. All four are partners in European consortium Airbus Industrie, which is not party to the study in its own right. Airbus Industrie researchers are already looking at the possibility of producing its own extra-large 600-seater plane. The new joint study will examine the market requirements for a Very Large Commercial Transport aircraft (VLCT) capable of carrying between 550 and 800 passengers with a potential range of between 7,000 and 10,000 nautical miles (13,000 to 19,000 kilometres). The companies are also examining the possibility of forming a consortium to develop, produce, market, sell and support such a plane. Their study will be headed by two project directors: Mr Jurgen Thomas, representing the Europeans, and Mr John Hayhurst, representing Boeing. ''Based on preliminary research, we currently believe that such a project would be too big for any one manufacturer,'' said Mr Hayhurst, Boeing's vice-president for large aircraft development. ''Studies indicate there may be a need for a larger aircraft around the turn of the century, but the market for such a plane is limited.''