The NASA Langley Research Center received authorization from NASA Headquarters on September 18, 2017 to acquire three excess C-20B Gulfstream III aircraft from the U.S. Air Force. Two of these aircraft will be used as parts support for the Agency, and the third aircraft will be used for research. The research G-III (C-20B) aircraft, designated NASA 520, will replace the Dassault HU-25A Guardian aircraft (NASA 524) as soon as practical. The research aircraft arrived at NASA Langley on December 7, 2017.  NASA Langley has installed an engine hush kit and  two nadir portals in the fuselage. The hush kit enables the aircraft to be Stage III noise compliant, allowing the aircraft to deploy nationwide and worldwide without requiring engine noise waivers. The nadir portals allow the aircraft to install earth science sensors, as is currently possible with the Center’s two King Air aircraft and the HU-25A aircraft. The NASA Langley G-III aircraft will ready for research at NASA Langley in January 2020.