At the beginning of the 1970s a more powerful variant of the Model 205 (UH-1H) had been studied in which a 1,900shp Lycoming T53-L-702 turboshaft had replaced the standard 1,400shp T-53-L13 unit. The version, designated Model 214 HueyPlus, also retained the main rotor and tail rotor drive systems and the larger two-blade rotor of the Model 309 KingCobra (composite elasto-meric), these offering better high speed and weight performance as well as reduced noise. The airframe was also strengthened including the pylon structure and fuselage.
The Model 214 prototype flew for the first time at Arlington in October 1970 powered by a 2185kW Avco Lycoming LTC4B-8D turboshaft engine. Development of the HueyPlus progressed steadily until 1972 when Iranian Army Aviation approached Bell for the design of a UH-1 derivative which could be operated in hot and high conditions. Several hundreds of this new type of helicopter would be delivered together with some two hundred AH-1J Cobras. A $500 million contract for 293 machines was signed on 22 December, 1972, by the US Army, acting on Iran's behalf.
During the first phase of this programme, Bell built three additional prototypes of the Model 214. These were powered by 2,050shp Avco Lycoming T55-L-7C turbo-shafts, and in August 1972, one of them was shipped to Iran for evaluation. The tests were considered successful and Bell moved on to the Model 214A which was the production model. On this variant, power was increased further by the installation of a 2,930shp Avco Lycoming LTC4B-8D turboshaft which permitted operation at a greater gross weight. Three prototypes of the Model 214A were prepared by Bell (c/n 27001/27003), the first (N214J) making its maiden flight on 13 March, 1974. The second prototype flew in April 1974 and the third in May. Flight testing and certification were resumed in the following year.
The first production 16-seat Model 214A (c/n 27004) was taken in charge by the Iran Imperial Army Aviation (IIAA) on 26 April, 1975, which gave them the name Isfahan. Three days later, on 29 April, this aircraft with Maj-Gen Manouchehr Khosrowdad, commander of the IIAA, and Clem A Bailey, Bell's assistant chief production test pilot, at the controls, established five new world records in the FAI Class E-1e. The helicopter reached a maximum altitude of 9070m and sustained a horizontal altitude of 9010m for 30 seconds. It also climbed to 3000m in 1min 58sec; to 6000m in 5min 13.2sec and to 9000m in 15min 05sec.
Subsequently, 39 generally similar aircraft, but with specific equipment for SAR operations, were delivered to the Iranian Air Force under the designation Bell Model 214C. The second batch was ordered in February 1976, and delivered between January 1977 and March 1978. A third batch of six Model 214As was ordered in March 1977 and this order was completed by the autumn of 1978.
The last Model 214A of the first batch was completed on 19 December, 1975.
Known as Model 214B BigLifter, this helicopter received FAA type certification on 27 January, 1976, but saw limited success and no more than seventy were produced. The Model 214B was externally similar to the Model 214A with the exception of an additional window in the side sliding door. Other differences included a fire-fighting system and new avionics. The Model 214B-1 variant was certificated under a different weight specification.
In its Isfahan plant, Iran intended to produce a larger and more powerful variant of the Model 214A capable of carrying up to 16 people and incorporating a stretched and widened fuselage. A Model 214A was modified by Bell with the installation of two 2,250shp General Electric T700/T1C turbo-shafts and tested in Iran in February 1977. The definitive Model, known as Model 214ST (ST stood for 'Stretched Twin', but this was later modified to 'Super Transport'), had its fuselage stretched by 2.44m. Bell assembled three prototypes (two for commercial certification and one of the military variant, c/n 18401/ 18403).
Bell initiated the production of a first batch of 100 Model 214ST in November 1979. The first prototype (c/n 18401, N214BH) flew on 21 July, 1979. The production examples were powered by 2,930shp Avco Lycoming LTC4B-8Ds driving a large five-blade rotor with Noda-Matic head. In 1982, the Model 214ST received FAA and CAA type certification for VFR and IFR operations. The 214ST is fully IFR certified and has a computer-controlled fly-by-wire automatic elevator trim system, plus a stability and augmentation control system and main rotor blade in-flight tracking system. A version with wheel undercarriage was certificated in March 1983.
Designed for long-range offshore oil operations with cruise speeds of 140 knots, the 214ST operates to 650 kilometres range with 45 minutes reserve. Bell's Super Transport can lift over three tons even on hot days at high altitudes. The Super Transport General Electric CT7-2A engine modules are designed for mechanical simplicity, requiring only 12 basic tools for line maintenance and module replacement. Options such as life rafts, pop-out floats, internal hoist or two 310 litre auxiliary tanks can be added.
Two versions were available, and the standard Model 214B was intended for a variety of purposes. They included operation as a 14-passenger transport with a crew of two; as a cargo lifter, with an external cargo hook certificated to carry a maximum load of 3629kg; in an agricultural role, carrying a very similar chemical load; or as a firefighter able to drop a total 2725 litres of fire retardant, carried in cabin and under-fuselage tanks. The alternative Model 214B-1 was certificated to different standards that allowed for operation at a lower gross weight with an internal load. The Model 214B was available to commercial operators from the receipt of certification on 27 January 1976 until production ceased in 1981.
The 214B BigLifter is derived essentially from the 204 and 205, and was specifically designed to better the lift capacity of any contemporary civil helicopter of the same power. The key to the type's considerable lifting ability is the use of a 2930shp Lycoming T5508D turboshaft (the civil version of the T55-LTC4B-8D turboshaft powering the 214A and its search-and-rescue derivative, the 214C), flat-rated to 2250shp maximum output. The rotor and transmission are identical with those of the 214A, the transmission being capable of accepting up to 2050shp at take-off and 1850shp for continuous running.
The rotor system is of an advanced type, the blades having swept tips and the hub featuring elastomeric bearings on the flapping axis. The twin-blade tail rotor has a hub which needs no lubrication. Other advanced features of the type are the use of an automatic flight-control system, with the capability of altitude maintenance and augmented stability; dual hydraulic systems; a nodalized suspension (Bell's patented 'Noda- Matic' concept of 1972, by which the fuselage is suspended from points of no relative motion in the engine mounting) to reduce fuselage vibration by about 80%; and an engine decking that is also used as a maintenance platform for the engine, transmission and rotor hub.
The 214B BigLifter carries to an extreme the Bell design philosophy of a twin-blade wide-chord main rotor, each of the blades having a chord of no less than 88.9cm. The transmission and rotor-drive systems are well proved by earlier use in the 214A, after development in the experimental KingCobra gunship helicopter.
Although it is intended mainly as a weight-lifter, the 214B can carry up to 14 passengers in addition to its crew of two. As a weight-lifter, however, the 214B can carry up to 1814kg internally, or up to 3175kg externally on its cargo hook, which is cleared for flight with loads weighing up to 3629kg. This weight-lifting capacity is also useful in the agricultural role, in which up to 3629kg of chemicals or 3023 litres of liquid can be uplifted. The considerable liquid-carrying capability of the 214B is also useful for fire-fighting.
The Model 214B-1 is intended for different certification standards, and is thus limited in the internal load-carrying role to a maximum take-off weight of 5670kg.
Production began in 1981, deliveries started in 1982 and by the beginning of 1984, some twenty machines were in service and seventy-eight had been delivered by early 1988. Among the first operators were British Caledonian Helicopters (c/n 28109/28110; G-BKFN and G-BKFP) which operated offshore in the North Sea and People's Republic of China. By 1992 some two hundred Model 214STs have been sold. The bulk of the Model 214ST production has found its way on to the civil market and only a few have been delivered to military customers: Brunei (one), Peru (eleven), Thailand (nine) and Venezuela (four) and Sultan of Oman's Air Force which operated eight Model 214B/STs from Salalah during the war against Iraq in January/February 1991.
The Bell 214ST features:
ROTOR SYSTEM: Two-blade advanced technology main rotor. Each blade has a unidirectionally laid glass fibre spar, with a 45degree wound torque casing of glass fibre cloth. The trailing-edge is also of unidirectional glass fibre, and the space between spar and trailing-edge is filled by a Nomex honeycomb core. The entire blade is then bonded together by glass fibre wrapping, with the leading-edge protected by a titanium abrasion strip and the tip by a replaceable stainless steel cap. Two-blade tail rotor; interchangeable blades, each with a stainless steel leading-edge spar and covering, aluminium honeycomb core and glass fibre trailing-edge strip. Main rotor head incorporates elastomeric bearings. Second-generation Noda-Matic nodal suspension system. Nodal beam requires no lubrication. Main rotor brake standard.
ROTOR DRIVE: Main transmission has a maximum rating of 1,752kW, maximum continuous rating of 1,454kW, and single-engine rating of 1,286kW. Combining, intermediate and tail rotor gearboxes, each with 1 hour run-dry capability.
FUSELAGE: Conventional all-metal semi-monocoque structure, incorporating rollover protection ring.
TAIL SURFACE: Electronically controlled elevator, which minimises trim changes with alterations of power and CG, and improves longitudinal stability.
LANDING GEAR: Choice of energy absorbing non-retractable tubular skid-type or tricycle-type wheeled landing gear.
POWER PLANT: Two 1,212kW General Electric CT7-2A turboshafts, connected to a combining gearbox. In the event of an engine failure, the remaining engine is capable of developing 1,286kW to provide continued flight capability. Standard fuel capacity 1,647 litres, contained in seven interconnected rupture-resistant cells, arranged to provide two independent fuel systems as required by FAR Pt 29. Single-point refuelling. Auxiliary fuel system optional, consisting of two tanks in rear of cabin, each of 329 litres capacity; 95 litre underseat auxiliary fuel tanks also available. Engine anti-icing and inlet screens standard.
ACCOMMODATION: Standard seating for pilot, co-pilot and up to 18 passengers. Dual controls standard. Crew seats adjustable. Passenger seats in three rows across cabin plus a two-place bench seat on each side of rotor mast. Standard configuration offers utility or de luxe interiors with contemporary or energy attenuating seats. Jettisonable crew door each side. Large cabin door on each side for passengers or easy loading of cargo. Glass windscreens, with standard anti-icing system. Two emergency exits on each side. Baggage space aft of cabin, capacity 1.84cu.m. Passenger seating removable to provide 9.23cu.m of cargo capacity. Cabin heated and ventilated.
Powered by a 2,185kW (2,930 shp) Lycoming LTC4B-8D turboshaft engine, an improved version of the T55-L-7C fitted to the original Model 214A demonstrator when it went to Iran. It has the 1,528kW (2,050 shp) transmission and rotor drive system developed for the KingCobra experimental gunship helicopter and embodies Bell's NodaMatic nodalised beam concept to minimise vibration. 296 delivered to the Iranian Imperial forces.
Commercial version of the 214A, announced on 4 January 1974, providing better lift capability than any commercial helicopter then in production. Powered by a 2,183kW (2,930 shp) Lycoming T5508D turboshaft, it has the same rotor drive and transmission system as the 214A. The engine is flat-rated at a maximum 1,677kW (2,250 shp) and the transmission at 1,528kW (2,050 shp) for take-off, with a maximum continuous power output of 1,379kW (1,850 shp). Advanced rotor hub with elastomeric bearings on the flapping axis; raked tips to main and tail rotors. Other features include an automatic flight control system with stability augmentation and attitude retention; nodalised suspension; separate dual-hydraulic systems; a large engine deck which serves as a maintenance platform; addition of an engine fire extinguishing system; push-out escape windows in the cargo doors, and commercial avionics.
As 214B, but with restricted internal gross weight of 5,669kg (12,500 lb).
Search and rescue variant of 214A. Total of 39 delivered to Iran.
Stretched twin-engined military version originally developed for production and service in Iran; but later transformed into commercial transport.
Bell Model 214B
Engine: 1 x Avco Lycoming T5508D turboshaft, 2185kW, 2050 hp
Main rotor diameter: 15.24m
Disc loading: 7 lb/sq.ft.
Pwr loading: 4.7 lb/hp.
Take-off weight: 6260k g / 13,800 lb
Empty wt: 7696 lb
Equipped useful load: 6059 lb.
Payload max fuel: 3595 lb.
Range max fuel/ cruise: 223 nm/ 1.5 hr.
Range max fuel / range: 256 nm/ 2.0 hr.
Service ceiling: 20,000 ft.
Max cruise: 146 kt.
Max range cruise: 131 kt.
ROC: 2280 fpm.
HIGE: 15,200 ft.
HOGE: 10,700 ft.
Max sling load: 8000 lb.
Standard fuel capacity 772 litres
Max fuel aux tank: 1,434 litres.
Accommodation: One or two pilots and 14 to 15 passengers.
Bell Model 214ST Super Transportghts
Engine: 2 x General Electric CT7-2 turboshaft, 1212kW, 1195 shp
Rotor diameter : 52.165 ft / 15.9 m
No. Blades: 2.
Disc loading: 8.2 lbs/sq.ft.
Power loading: 5.4 lbs/hp
Max take off weight : 17507.7 lb / 7940.0 kg
Weight empty : 10143.0 lb / 4600.0 kg
Max ramp weight: 17,500 lbs
Max useful load: 7987 lbs.
Max landing weight: 17,500 lbs.
Max sling load: 8000 lbs.
Length with rotors turning: 18.95m / 62.1 ft
Fuselage length : 50.197 ft / 15.3 m
Height : 15.748 ft / 4.8 m
Max. speed : 140 kt / 259 km/h
Normal cruise @ 3000 ft: 139 kts.
Fuel flow @ normal cruise: 906 pph.
Endurance @ normal cruise: 3 hr.
Initial climb rate : 1771.65 ft/min / 9.0 m/s
Service ceiling : 12598 ft / 3840 m
Hover in ground effect: 7800 ft
Range : 463 nm / 858 km
Hovering ceiling, IGE: 3170m
Fuel capacity : 435 gal / 1647 l
Crew : 2
Passengers : 18