Harry R. Steffensen, 53, the assistant finance director of Fairfax County and a retired Air Force lieutenant colonel who was a decorated veteran of two wars, died Saturday at Fairfax Hospital after a heart attack. He lived in Vienna.

Col. Steffensen was a fighter pilot in Korea during the conflict there. He flew electronic surveillance aircraft in Vietnam between 1968 and 1969. He was stationed in Germany before coming to Washington, where he was assigned to a directorate of the office of the Air Force deputy chief of staff for research and development. He retired from active duty in 1973.

His decorations included two Distinguished Flying Crosses and nine Air Medals.

Since retiring from the Air Force, Col. Steffensen had worked for Fairfax County, first as a management analyst and finally as the county's assistant finance director.

Col. Steffensen was a native of Forest City, Iowa, and received his Air Force commission following his graduation from the U.S. Military Academy at West Point in 1950. He also earned a bachelor's degree in aeronautical engineering at the University of Oklahoma and a master's degree in business administration at the Univeristy of Connecticut. He was a graduate of the Command and General Staff College at Fort Leavenworth.

Survivors include his wife, Lois M., of Vienna; two daughters Janet S. Johnson of Fairfax, and Carol S. Huff of Dumfries; a son, James H., of Reston; his father and stepmother, Mr. and Mrs. Harry N. Steffensen, and a sister, Helen Wooge, all of Forest City, and one grandchild.

The family suggests that expressions of sympathy be in the form of contributions to the Northern Virginia Chapter of the American Heart Association.