According to a Budget Request Overview report for the United States Department of the Air Force (DAF), the biggest allocation (61,407,391) was for the Operations and Maintenance service.
According to the FY2019_Budget_Request_Overview_Book | 8-12, the Department of Defense claims the Department of the Air Force is as follows Department of the Air Force Operation and Maintenance 61,407,391 Military Personnel 38,954,308 Procurement 50,541,275 RDT&E 40,492,614 Military Construction 2,303,699 Family Housing 395,720 Revolving and Management Funds 77,644 The United States Department of the Air Force (DAF) is one of the three military departments within the Department of Defense of the United States of America. 
