George J. Cleary Jr., 69, retired chief electrical engineer with the Department of the Air Force, died Wednesday at his home in Mitchellville, Md., after a heart attack.

From 1950 until retiring in 1970, he held various positions with Air Force headquarters here. He was chief electrical consultant to the directorate of civil engineering when he retired.

Born in Washington, Mr. Cleary worked his way up from apprentice electrician to electrical superintendent in 1938 on various area projects.

From 1943 to 1945, he was a civilian electrical engineer with the 3d Service Command at Army headquarters here.

In 1936, Mr. Cleary established Associated Electric Co., engineering and contractors. He designed the electrical distribution system for Georgetown University among many major projects.

After retiring from the Air Force, he developed the Willow Grove subdivision in Mitchellville and established George J. Cleary Associates, earthmovers and septic system contractors there.

Mr. Cleary had served on the standing committee on diesel engineers of held numerous honors, including the Air Force Meritorious Service and Superior Service awards.

He is survived by three daughters, Loretta Groves and Maureen Curtis, of Mitchellville, and Patricia Conway, of Morgan Hill., Calif.; five sons, Frank J. and George J. III, both of Mitchellville, Richard R., of Upper Marlboro, and James P. and Robert P., both of the home; four sisters, Loretta Mac Gregor, Olivia Merrillatt and Margaret Grambo, all of Silver Spring, and Katherine Cordes, of Arlington, and 19 grandchildren.