A US Air jetliner carrying 61 persons made an emergency landing at Andrews Air Force Base yesterday afternoon after encountering severe turbulence while preparing to land at National Airport, authorities said.

A flight attendant suffered a chipped tooth and was treated at the base hospital for a cut lip, and two passengers were taken to the hospital for observation, officials said. None was reported admitted.

The twin-jet DC9, on its way here from Buffalo, N. Y., was about four miles east of National at about 9,000 feet when it encountered "very severe turbulence" in a weather front about 4 p.m., according to a Federal Aviation Administration spokesman. The plane, with 56 passengers and a crew of five, "was bounced around pretty good," said David H. Shipley, a US Air assistant vice president.

He said the pilot wanted to land as quickly as possible and check the plane for possible damage, and so elected to land at the military air base in Prince George's County. Landing a commercial airplane at a military base requires that the pilot declare an emergency.

Passengers were taken by bus to National Airport and mechanics were sent to Andrews to examine the plane. As of late last night no damage had been reported found, but the plane was still at Andrews.

The incident occurred as weather delayed takeoffs and landings at National Airport for a few minutes.