Upon completing his technical training in February 1919, Hegenberger became chief of the Instrument Branch at McCook Field, Dayton, Ohio. He was commissioned a first lieutenant, Air Service, in the Regular Army July 1, 1920, and subsequently served as assistant engineer of the Equipment Section, Air Service Engineering Division. Hegenberger transferred overseas to the 72nd Bombardment Squadron at Luke Field, Hawaii, in October 1923, and later served as operations officer of the 5th Composite Group. In March 1925, he was transferred to the 5th's 23rd Bombardment Squadron.