Following the Axis attack on Yugoslavia in April 1941 and the occupation of Yugoslavia, "Rogožarski" factory started production for the German war industry, so eng. Milutinovic refused to continue working for the company, and remained engaged as professor at the University, though no classes were held. Right after the liberation of Belgrade in October 1944, he returned to Rogozarski as a technical manager of the company which now organized repair and revision of airplanes for the needs of the Red Army and the Yugoslav air force. During that period, he was finishing the reconstruction of shock absorbers and upgrading of landing gears for JAKs, Jakovljev fighters.