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Bell 427



Launched as the New Light Twin (NLT) in February 1996 on signature of collaborative agreement with Samsung Aerospace Industries of South Korea. The Bell 427 prototype assembly began early 1997.

An enlarged and lengthened by 13 inches version of Model 407 with wider cabin, centre-section fuel tank, OH-58D composite four-blade main rotor, and 2705kg TOGW, powered is from two 600shp Pratt & Whitney PW206D turboshafts.

The first flight of the first prototype (C-GBLL) was on 11 December 1997 at Mirabel, Quebec. The second prototype (C-FCSS) was completed in February 1998 and the two prototypes undertook flight test programme, gaining Transport Canada certification on 19 November 1999, FAA VFR certification achieved in 24 January 2000, followed by Dual Pilot IFR (DPIFR) Category A certification on 24 May 2000.

The first production aircraft (C-GDEJ) was flown in June 1998. Compared with prototypes, the production 427 has longer exhausts and revised upper surface contours.
Similar in appearance to the Bell 407, with a cabin stretch of 33cm, the 427 is all-new design, incorporating twin-engine safety margins. Flight dynamics are based on the four-blade rotor system of Bell OH-58D Kiowa, allied to tail rotor of Bell 407, and folding main blades.

A purpose-designed 'flat pack' main transmission, with direct input from both engines, has only four gear meshes to simplify design and operation. The transmission is attached to the airframe by four liquid-inertia vibration eliminators. It was the first Bell helicopter designed entirely with use of computer (Dassault CATIA programme).
The structure is generally as for the Bell 206, but extensive use of carbon/epoxy composites reduces airframe parts count by some 33%. Cabin floor and roof are flat panels for ease of manufacture; minimal use of curved panels elsewhere. Composites main and tail rotors; main blades have nickel-plated stainless steel leading-edges. Soft-in-plane hub of main rotor employs a composites flexbeam yoke and elastomeric joints, eliminating lubrication and maintenance requirements. Brake and main rotor blade folding optional. Composites cabins and rolled aluminium tailbooms built by Samsung; assembly in Canada, except for sales to Korea and China; Hexcel honeycomb as stiffener. The landing gear is twin skids with dynamically tuned cross tubes to reduce ground resonance. Low skids standard; optional high skids and emergency floats.

Fuel is contained in three crash-resistant tanks; two forward, one aft, with a total usable capacity of 770 litres. One forward fuel tank can be removed in EMS configurations to provide additional stretcher space in cabin or to permit stretcher to extend into port side of cockpit. Oil capacity (total, both engines) 10.2 litres.

Standard accommodation is for two crew in cockpit, on 20g energy-attenuating seats, and six passengers in cabin on two rows of three, seats in club configuration (all-forward-facing scats optional); all scats equipped with inertia-reel shoulder harnesses. Optional EMS interiors provide for carriage of one or two stretchers with up to two medical attendants, affording either full patient or head-only in-flight access, with single- or two-person crew. In cargo configuration, with all passenger seats removed, an optional removable flat cargo floor can be installed, equipped with integral tie-downs. Two forward-hinged doors each side; cabin doors, both sides, are forward-hinged, but port unit can be replaced by optional rearward-sliding door for cargo handling. External door on starboard side to rear baggage hold.

Orders for 22 were placed during the mockup's first public display at Farnborough Air Show 1996, and 85 were on order by May 2000 from 50 customers. Deliveries began 2000 five delivered that year, 15 in 2001 and five in 2002.

Engines: Two Pratt & Whitney Canada PW207D turboshafts with FADEC, each 529kW for T-O (5 min) or 466kW max continuous
OEI ratings: 611kW for 30 sec, 582kW for 2 min, 559kW for 30 min or 529kW max continuous.
Twin-engine transmission rating: T-O & max continuous: 597kW.
OEI transmission rating: 485kW for 30 sec: 451kW for 2 min; 343kW max continuous.
Main rotor rpm: 395  
Tail rotor rpm: 2,375
Main rotor diameter: 11.28m
Fuselage length: 10.9m
Take-off weight: 2722kg
Empty weight: 1581kg
Max speed at sea level: 252km/h
Cruising speed at sea level: 240km/h
Hovering ceiling, OGE: 4235m
Hovering ceiling, IGE: 4940m
Range at sea level: 663km
Crew: 1
Passengers: 6-7




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