Bell / Agusta Aerospace BA 609
Bell and Boeing revealed in February 1996 that studies were in progress for a nine-passenger civil tiltrotor aircraft in the 6,350kg weight class, with the preliminary designation D-600. On 18 November 1996, the two companies announced that a joint venture was being established to design, develop, certify and market a six- to nine-passenger civil tiltrotor as the Bell Boeing 609. The machine has engines which pivot 90 degrees so it can take off vertically like a helicopter, then fly horizontally like a plane.
Boeing withdrew as a partner on 1 March 1998 and Bell formally announced at the Farnborough Air Show in September 1998 that they had teamed with Agusta. Agusta was investing and participating in BA609 development and was to be responsible for assembly of BA609s sold in Europe and elsewhere.
Preliminary design review completed May 1997. Manufacture of parts for the prototypes began in Philadelphia, August 1997, and a full-size mockup was exhibited at the Paris Air Show in June 1997.
With a T-tail configuration and composite cross-shafts to keep both prop rotors turning in event of engine failure. Manual screwjack facility exists whereby the prop-rotors can be tilted into helicopter mode if the cross-shafts fail. Designed using three-dimensional CATIA digital computer design system, the airframe has design life of 20,000 flight hours.
The aluminium fuselage structure has composites skinning and composites wings. The undercarriage is a retractable tricycle type, with twin nosewheels and single wheel on each-main unit.
Control is by a BAB Systems triplex digital fly-by-wire flight control system, with Dowty Aerospace actuators. The T tail has conventional elevators and no rudder. Two-segment trailing-edge flaperons are fitted.
Two 1,447kW Pratt & Whitney Canada PT6C-G7A turboshaft enginesc are installed in tilting nacelles at the wingtips, each driving a three-blade proprotor. Nacelle transition is achieved in 20 seconds. Fuel is in integral wing tanks with a usable capacity of 1,401 litres, and provision for auxiliary fuel tanks.
The airframe carries a crew of two, side by side on flight deck, with dual controls, and a maximum of nine passengers in the standard aircraft. A crew and passenger door is on the starboard side, forward of wing. The cockpit is pressurised and air conditioned; pressurisation differential 0.38 bar.
Ground-running trials began on 6 December 2002 and the first flight of the prototype (N609TR) took place (in the vertical mode only) on 7 March 2003 in Arlington, Texas, rescheduled from late 2002. The Bell/Augusta Aerospace Co said its BA 609 tilt-rotor aircraft flew at an altitude of about 15m in its first test flight.
Four prototypes were produced for a 36-month flight test programme leading to certification in January 2007 under FAR Pt 25 (fixed-wing aircraft) and Pt 29 (helicopters), plus Pt 21.17(b) Special Conditions for unique components. The first prototype were used primarily for expansion of flight envelope, while the second, third and fourth airframes were dedicated to systems certification, avionics and icing approval, and FAA function and reliability, respectively.
The order book opened on the 2nd of February 1997 at Heli Expo, with the first order placed soon after by an unspecified customer. A total of 70 were ordered by 40 customers in 18 countries by March 2003. A briefing was given to the US Coast Guard, late 1997, followed by a demonstration by the XV-15 tiltrotor concept demonstrator aboard the Coast Guard cutter Mohawk off Key West, Florida, in May 1999.
In 1998 Bell Helicopter Textron acquired Boeing’s 49% interest in the Bell-Boeing 609 civil tiltrotor and has assumed full ownership.
Engine: 2 x Pratt & Whitney PT6C-67A, 1360kW / 1850hp
Empty weight: 6300kg
Max speed: 510km/h