Ada Averill Hains, 71, who was active in volunteer and service-connected organizations, died of cancer Thursday at the Malcolm Grow Medical Center at Andrews Air Force Base.

A native of New York City, she was the daughter of the late Army Col. Nathan King Averill, a career Army officer, and the wife of retired Army Maj. Gen. Peter C. Hains III, who commanded armored units in Europe and the Pacific during World War II.

Mrs. Hains belonged to the Army Relief Society, the Military Wives Association, and the Army-Navy Chapter of the Daughters of the American Revolution.

She first came to Washington during World War II and retired with her husband to Gibson Island, Md., in 1961.

Since 1961 she had helped run Red Cross life-saving classes and golf clinics for young people.

Mrs. Hains was a member of St. Jane Frances Catholic Church in Riviera Beach, Md.

In addition to her husband of the home, she is survived by a daughter, Ada Lou Brentnall, of Bedford, Mass.; three sons, Army Col. Peter C., of Austin, Tex., John N., of Suffern, N.Y., and Fred O. of Baltimore; two sisters, Mary Crimmins, of Menlo Park, Calif., and Dorothy (Dotty) Sears, of Whispering Pines, N.C.; a brother, Dr. John Averill, of Tryon, N.C., and eight grandchildren.