The Carter administration, signaling another step in the expanding U.S. military relationship with China, will now consider sales to Peking of transport aircraft and helicopters.

This latest expansion, officials said, grows out of the basic decision to sell China militarily useful equipment -- though not weapons. The decision was made by President Carter early in January, shortly after the Soviet invasion of Afghanistan and on the eve of Denfense Secretary Harold Brown's trip to Peking.

On that trip, Brown said Washington had made it clear to Peking that the United States would consider, on a case-by-case basis, sales of technology and equipment that could have dual uses, meaning military as well as civilian.

Late in January, the Pentagon publicily said that trucks, communications equipment and radars were examples of the type of equipment that could be sold.

Now, however, it is clear that the administration is prepared to jump to a much more expensive and flexible type of equipment that could give added maneuverability to Chinese ground and supply forces, which are big but sorely lacking in transportation.

In addition to the aircraft, the list of potential sales now includes flight simulators to help train pilots, aerial cameras and "special purpose" cameras.

Though the implications of this are undoubtedly being discussed in Moscow, the administration is letting its list out in a low-key manner. The details will be found in the next issue of the Munitions Control Newsletter to be published by the State Department later this week. The newsletter is meant to provide guidance for contractors who may be interested in such sales.

The newsletter lists types of support equipment the United States is prepared to consider on a case-by-case basis for export licensing to China. One category, it says, is "certain aircraft, including helicopters, designed, modified or equipped for . . . cargo or personnel carrying."

No actual decision or sale can be authorized until a U.S. manufacturer comes forward with a Chinese order request, but the Chinese have shown interest in U.S. helicopters.

Officials could not say immediately if preliminary decisions had been made to sell Peking, if it asks, four-engine C130 transports, which have been the backbone of the U.S. Air Force's battlefield supply operation for many years.