The Beechcraft T-6 Texan II is a single-engine turboprop aircraft. Based on the Pilatus PC-9, the T-6 has replaced the Air Force's Cessna T-37B Tweet and the Navy's T-34C Turbo Mentor. The T-6A is used by the United States Air Force for basic pilot training and Combat Systems Officer (CSO) training and by the United States Navy and United States Marine Corps for Primary and Intermediate Naval Flight Officer (NFO) training. The T-6A is also used as a basic trainer by the Royal Canadian Air Force (CT-156 Harvard II), the Greek Air Force, the Israeli Air Force (Efroni), and the Iraqi Air Force. The T-6B is the primary trainer for U.S. Student Naval Aviators. The T-6C is used for training by the Royal Moroccan Air Force, the Royal New Zealand Air Force and the Mexican Air Force.