models. MH-47E The MH-47E has been used by U.S. Army Special Operations. Beginning with the E-model prototype manufactured in 1991, a total of 26 Special Operations Aircraft were produced. All aircraft were assigned to 2–160th SOAR(A) "Nightstalkers", home based at Fort Campbell, Kentucky. E models were conversions from existing CH-47C model airframes. The MH-47E has similar capabilities as the MH-47D, but includes an increased fuel capacity similar to the CH-47SD and terrain following/terrain avoidance radar. In 1995, the Royal Air Force ordered eight Chinook HC3s, effectively a low-cost version of the MH-47E for the special operations role. They were delivered in 2001, but never entered operational service due to technical issues with their avionics fit, unique to the HC3. In 2008, work started to revert the HC3s to HC2 standard, to enable them to enter service. They have since been upgraded to HC5 standard with a digital automated flight control system. CH-47F In 2001, the first CH-47F, an upgraded CH-47D, made its maiden flight; the first production model rolled out on 15 June 2006 at Boeing's facility in Ridley Park, Pennsylvania, and first flew on 23 October 2006. Upgrades include Honeywell engines and the airframe featuring greater single-piece construction to lower maintenance requirements. The milled construction reduces vibration, as well as inspection and repair needs, and eliminates flexing points to increase service life. The CH-47F can fly at speeds of over with a payload of more than . New avionics include a Rockwell Collins Common Avionics Architecture System (CAAS) cockpit, and BAE Systems' Digital Advanced Flight Control System (DAFCS). AgustaWestland assembles the CH-47F under license, known as the Chinook ICH-47F, for several customers. Boeing delivered 48 CH-47Fs to the U.S. Army through August 2008; at that time Boeing announced a $4.8 billion contract with the Army for 191 Chinooks. A CH-47F Block 2 is planned to be introduced after 2020. The Block 2 aims for a payload of with and high and hot hover performance, eventually increased up to , to carry the Joint Light Tactical Vehicle; maximum takeoff weight would be raised to . It features the composite-based Advanced Chinook Rotor Blade (derived from the cancelled RAH-66 Comanche), 20% more powerful Honeywell T55-715 engines, and the active parallel actuator system (APAS); the APAS enhances the digital advanced flight-control system, providing an exact torque split between the rotors for greater efficiency. A new fuel system combines the three fuel cells