June 21, 2021 Propulsion Test Branch at Arnold AFB helping power the Air Force since 1950s The Engine Test Facility (ETF), which is part of the AEDC Propulsion Test Branch at Arnold Air Force Base, was the first facility on base, with its construction completed in 1953.Equipment making up the ETF test cells, such as the motors and compressors, were confiscated from a Bavarian Motor Works