Donald L. Chadwick, 63, an early aviator and a combat veteran of World War II, died Tuesday at Holy Cross Hospital after a long illness.

He came to Washington in 1950 and founded Chadwick Associates, Inc., manufacturers' representatives. He sold the firm about six years ago and since then had been associated with Ocean Chemicals, Inc.

Born in Denver, Mr. Chadwick learned to fly at an early age and was associated with the Tex Rankin Flying Service in Texas. In the early 1930s, he participated in aerial barnstorming and was a test pilot.

he organized and operated an intra-state airline in Oregon until 1939.

Two years later, Mr. Chadwick joined the Royal Canadian Air Force. He was posted to a Royal Air Force unit at Ossington, England, for combat training.

He flew several combat missions over Germany and in 1942 was assigned to the 426 Squadron, RAF Bomber Command in Yorshire.

On Dec. 27, 1942, on his 31st combat mission, Mr. Chadwick's bomber was shot down on a raid on Essen, Germany. He was a prisoner of war until his escape and return to England through Portugal in 1943.

He then joined Pan American Airwasy in Treasure Island, Calif., until 1944, when he was commissioned in the U.S. Navy. During the latter part of the war, he flew a number of combat missions in the famous Mosquito light bomber.

Mr. Chadwick joined United Air Lines in 1947 and remained with the firm until coming to Washington.

he had played a key role in the development of several national air shows and was an early supporter of the U.S. Aerobatic Team.

He was associated with the National Aviation Club, which honored him several years ago as a "Pioneer Aviation," and the Touchdown Club.

He is survived by hs wife, Frances, of the home in Silver Spring, and a son, Navy CPO Peter H. Chadwick, stationed in Hawaii.