Mike Opela, 544th Propulsion Maintenance Squadron Director, discusses the process of modifying a Marine STOVL F135 engine with Maj. Gen. Jeffrey L. Harrigian, Director of the Headquarters U.S. Air Force F-35 Integration Office, during a visit to the Air Force Sustainment Center and Oklahoma City Air Logistics Complex where the modification is performed. (U.S. Air Force photo/Marlin Zimmerman)