The Bell UH-1 Huey

v1.1.0 / 01 jan 02 / greg goebel / public domain

* The US Army's first operational turboshaft-powered helicopter, the Bell UH-1 "Huey", would prove one of the most successful rotorcraft in history, with over 16,000 built. The Huey was and remains a common sight in many of the world's military forces, and still is in first-line service in the US Marines. This document provides an outline history of the Huey.

[1] MODEL 204: ARMY HU-1A (UH-1A), HU-1B (UH-1B), UH-1C
[6] MODEL 214

[1] MODEL 204: ARMY HU-1A (UH-1A), HU-1B (UH-1B), UH-1C

* Although Bell had enjoyed little success with any of the company's piston helicopter designs besides the popular Model 47, the company found another winner on 23 February 1955, when Bell was awarded the contract for a new US Army medical evacuation ("medevac") helicopter, with the company designation of "Model 204" and the initial military designation of "XH-40". Three prototypes were ordered, with initial flight of the first prototype on 22 October 1956.

The Model 204 was Bell's first production turbine helicopter. It was powered by a Lycoming T53-L-1 turboshaft with 700 horsepower; used the traditional Bell main-tail rotor configuration, with a two-bladed rotors and a stabilizing "teetering bar" on the main rotor; and was fitted with skid landing gear. The tail boom was fitted with a horizontal tailplane to help keep the helicopter level in forward flight.

The three initial XH-40 prototypes were followed by six "YH-40" evaluation rotorcraft. The YH-40 featured a T53-L-1A engine derated to 770 horsepower and a cabin stretch of 30 centimeters (1 foot). The YH-40 could carry a pilot; copilot; and six passengers, or two stretchers and an attendant. Initial service delivery to the Army was on 30 June 1959, with the first of nine pre-production "HU-1 Iroquois" helicopters. "HU" stood for "Helicopter, Utility", and the "HU-1" designation quickly led to the nickname that would be famous: "Huey".

The Army followed up with orders for a total of production 183 "HU-1As", including 14 configured with dual controls and "blind flying" kit for instrument training. Deliveries of the UH-1A were completed in 1961.

The Army used the type for medevac in Alaska, Europe, and Korea. The HU-1 would be later deployed to Vietnam as the war there ramped up, and a number were field-fitted with a single Browning or M-60 7.62 millimeter (0.30 caliber) machine gun on a fixed mount next to each side door, and twin box forward-firing packs of 70 millimeter (2.75 inch) unguided rockets, with eight rockets per pack for a total of 16.

* The Army requested improvements to the Huey, and the result was a "HU-1B", with first delivery in March 1961. The HU-1B had a stretched fuselage to provide accommodations for seven passengers; three stretchers, two sitting casualties, and a medical attendant; or 1,360 kilograms (3,000 pounds) of cargo.

The HU-1B was powered by a T53-L-5 turboshaft engine with 960 horsepower, and was fitted with a redesigned and wider-span (13.4 meter or 44 feet) rotor blade. Late production UH-1Bs were fitted with a T53-L-11 turboshaft with 1,100 horsepower. Bell sold a commercial version of this variant designated "Model 204B" that was also purchased by some foreign military users. The Model 204B was rolled out in September 1960 and certified in April 1963. At least 1,033 UH-1Bs and Model 204s would be built in all.

In September 1962, the US military went to a new tri-service aircraft designation scheme, and the HU-1A became the "UH-1A", while the HU-1B became the "UH-1B". The UH-1B saw extensive service in Vietnam. It was initially fitted with the "M-6E3" armament system, which included two M-60 machine guns mounted on an outrigger outboard of each door, for a total of four, and the existing eight-round rocket packs. The machine guns could be aimed by the pilot using a cockpit-mounted sight and a hydraulic actuation system.

Transport versions of the UH-1 were known as "Slicks" because of their uncluttered appearance. They were generally armed with an M-60 machine guns on a flexible mount in each door to provide covering fire for troops.

The use of dedicated helicopter gunships to escort "Slicks" or "DustOffs" (as medevac Hueys were known) led to a demonstrable drop in combat damage. In fact, although some Army brass believed that helicopters were too fragile to engage in direct combat operations, Huey loss rates were found to be surprisingly acceptable.

* The UH-1B gunship lacked the power necessary to carry weapons and ammunition and keep up with transport Hueys, and so Bell designed yet another Huey variant, the "UH-1C", intended strictly for the gunship role. It featured an uprated T-53-L-11 engine, large fuel capacity, and a new "Model 540" rotor system, which eliminated Bell's distinctive "teetering bar" and replaced it with an electromechanical stabilization scheme. The Model 540 rotor system was known as the "door-hinge" rotor or the "Stability Control Augmentation Scheme (SCAS)". The new rotor also had a wider chord, and was both lighter and provided increased maneuverability.

The UH-1C was introduced in September 1965, but only about 750 were built, as by that time Bell was getting ready to introduce the optimized AH-1 "HueyCobra" gunship, which was based on UH-1C technology. The AH-1 "Cobra" provided greater speed and maneuverability and was a much more difficult target than the Huey gunships. Nonetheless, the Huey gunship would have its partisans, since its door gunners could lay down fire towards the rear of the helicopter and also provided extra sets of eyes. Huey gunships would in fact remain in service in Vietnam up to the end of the war, though that was mainly due to the fact that there weren't enough Cobras to replace them.



* UH-1B and UH-1C gunships were fitted with a series of improved armament systems:

A Huey gunship with an M-5 was called a "Frog"; one with the XM-3 was called a "Hog"; and one with both was called a "Heavy Hog". It appears that Huey gunships were known generally as "Cobras" or "Snakes" early in the war, but if so, such usage was dropped after the introduction of the AH-1, which became known by those terms instead.

There were of course many variations, such as fits that used the XM-159 19-round rocket pods in place of the XM-158 7-round pods, as well as improvised weapon mounts. Some Hueys were fitted with wooden chutes outside the doors to allow flight crew to drop mortar rounds on enemy positions, with aircrew simply yanking the bottom doors of the chutes open with wires to drop the loads. This "Mortar Aerial Delivery (MAD)" scheme was reportedly very effective in jungle fighting.

Some UH-1Bs were also fitted with six French "SS-11" wire-guided anti-tank missile, adopted by the US as the "AGM-22B", but this was never a popular weapon. The SS-11 had to be guided by "eyeball", with the operator tracking the missile by a flare in its tail and adjusting its course with a joystick. The course corrections were transmitted to the missile by wires that it spooled out in flight. Such a scheme required a highly trained operator and a fairly benign combat environment to be accurate, and as the first was in short supply and the second was almost a contradiction, accuracy of the SS-11 was very poor.

In the spring of 1972, in the last days of the US involvement in Vietnam, a number of UH-1Bs were fitted with the new BGM-71 "TOW (Tube-launched, Optically-tracked, Wire-guided)" missile. TOW, as its name implies, is a wire-guided missile like the SS-11, but has a much "smarter" guidance system. The weapons operator simply keeps the sight on target and the guidance system figures out the course updates.

81 TOW missiles were fired at that time, scoring 57 hits. In contrast, 20 SS-11 missiles were fired but only scored three hits. The use of TOW in Vietnam paved the way for its widespread adoption as a helicopter store in the post-Vietnam period.

* The last variant of the Model 204 bought by the Army was the "UH-1M", which was obtained both as new-built rotorcraft and as conversions from UH-1Cs. The UH-1M featured a T53-L-13 engine derated to 1,400 horsepower. It was fitted with the "Iroquois Night Fighter And Night Tracker (INFANT)" sensor system with a low-light-level TV and a searchlight, plus an M-21 gun system, with both the sensor and weapons systems built by Hughes.

The UH-1M went into service in Vietnam in 1969. Some sources claim that only a few were built for evaluation, but other sources state that several platoons were equipped with the type.



* In March 1962, Bell won a Marine Corps contract to supply the service with an assault support helicopter, resulting in the "UH-1E". The Marines obtained 250 UH-1Es, similar to the UH-1B but fitted with an external rescue hoist, a rotor brake to keep the rotor in place during shipboard stowage, and a Marine-optimized avionics fit.

First flight of the UH-1E was in February 1963. Deliveries began in February 1964. The Model 540 rotor system, used on the Army UH-1C, was introduced into UH-1E production in 1965. The Marines also obtained 20 "TH-1E" trainers.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   rotor width             13.41 meters        44 feet
   footprint length        16.15 meters        53 feet
   fuselage length         12.98 meters        42 feet 7 inches
   height                  4.44 meters         14 feet 7 inches

   empty weight            2,155 kilograms     4,750 pounds
   max loaded weight       3,855 kilograms     8,500 pounds

   maximum speed           220 KPH             140 MPH / 120 KT
   service ceiling         5,090 meters        16,700 feet
   range                   340 kilometers      210 MI / 185 NMI
   _____________________   _________________   _______________________

* In June 1963, Bell won a US Air Force contract for a helicopter to perform missile site support duties, resulting in the "UH-1F", a derivative of the UH-1B. The UH-1F had an even wider 14.63 meter (48 foot) diameter rotor and a General Electric (GE) T58-GE-3 turboshaft engine with 1,290 horsepower. The first UH-1F flew on 20 February 1964, with deliveries beginning in September 1964. A total of 146 were built.

A number of UH-1F were built as or converted to "UH-1P" psychological warfare rotorcraft, carrying loudspeakers over the jungles of VietNam to call on the enemy to surrender. A few "TH-1Fs" were also built for instrument flying and hoist training.

* Bell also developed a variant of the UH-1B designated the "HH-1K" for the US Navy, with 27 built for "search and rescue (SAR)" duties. These rotorcraft were fitted with a Lycoming T53-L-13 engine derated to 1,400 horsepower and had Navy-specified avionics. Initial deliveries were in 1970. 90 more were built as training helicopters under the designation "TH-1L Seawolf", and eight were built as "UH-1L" utility rotorcraft.

The Navy also operated hand-me-down Army UH-1B gunships in Vietnam, in support of river patrol boats. The gunships would scout ahead of the patrol boats to look for ambushes and back up the boats during an attack. Various Huey models were also operated by "Air America", a front company operated by the US Central Intelligence Agency that performed various clandestine and semi-clandestine air activities.



* Even as Bell was working on improved versions of the Model 204, the company was developing a new series of "stretched" Hueys, with the company designation of "Model 205". Bell proposed the concept to the Army in 1960, leading to award of a contract in July 1960 for seven "YUH-1D" prototypes.

The Model 205 first flew on 16 August 1961 and was introduced into service in August 1963 as the "UH-1D". It featured a Lycoming T53-L-11 turboshaft engine with 1,100 horsepower; a 14.63 meter (48 foot) rotor; greater fuel capacity and provisions for auxiliary tanks; and a load capacity of 12 to 14 passengers, six litters and a medical attendant, or up to 1,800 kilograms (4,000 pounds) of cargo. It is easily distinguished from the Model 204 by the fact that the side doors have two windows, rather than one.

The Model 205 became the Army's primary combat transport and medevac helicopter in Vietnam. The smaller Model 204 variants were generally assigned to the gunship role. The Army bought a total of 2,008 UH-1Ds.

* The UH-1D led to the improved "UH-1H", which was generally similar, but was fitted with the more powerful T53-L-13 engine derated to 1,400 horsepower, as well as avionics for night and bad-weather operation, and a Decca radio navigation system.

The UH-1H rolled off the manufacturing line in September 1967 and remained in production for 20 years. The US Army obtained a total of 3,573 UH-1Hs, and many remain in service, mostly with Army Reserve / National Guard units. They have been kept current with new avionics, improved composite rotor blades, countermeasures equipment such as chaff-flare dispensers and infrared jammers, and other updated gear.

Three UH-1Hs were modified to the "EH-1H" signals intelligence (SIGINT) standard. Many more such updates were planned, but the Army decided to adopt the Sikorsky "EH-60C" Black Hawk for this role instead. 220 UH-1Hs were converted to the "UH-1V" medevac standard, with a rescue hoist and revised avionics. The USAF also obtained 30 similar "HH-1Hs" with a rescue hoist for short-range SAR.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   rotor width             14.63 meters        48 feet
   footprint length        17.62 meters        57 feet 10 inches
   fuselage length         12.77 meters        41 feet 1 inch
   height                  4.41 meters         14 feet 6 inches

   empty weight            2,365 kilograms     5,210 pounds
   max loaded weight       4,310 kilograms     9,500 pounds

   maximum speed           205 KPH             125 MPH / 110 KT
   service ceiling         3,840 meters        12,600 feet
   range                   510 kilometers      320 MI / 280 NMI
   _____________________   _________________   _______________________

1,372 UH-1Hs were also built for export sales, not counting foreign license manufacture.

* In Vietnam, the Model 205s were generally fitted with an M-60 machine gun in each door as well as armor, reducing passenger lift capacity to about 7 or 8 troops. The UH-1H with its more powerful engine was regarded as vastly superior to the UH-1D in terms of lift capacity, particularly under "hot and high" (hot temperature and high ground altitude) conditions, and became the standard DustOff helicopter.

DustOffs were generally fitted with rescue hoists, which could be fitted with simple harnesses; harnesses that could penetrate jungle canopy; or various types of litters. DustOff operations were usually unescorted and very hazardous, with loss rates about three times greater than those for other types of helicopter operations. DustOffs were unarmed except for personal sidearms and painted with red crosses, but Vietnam was not a war of niceties and the red crosses only seem to have made them a better target.

A total of 4,869 helicopters were lost by US forces in Vietnam. The US Army's Hueys took the biggest part of these losses, a total of 2,591. Interestingly, only 1,211 Hueys were lost in combat, while 1,380 were lost in operational accidents. Statistics showed that helicopters were by no inherently vulnerable, with a loss rate of less than one in 8,000 sorties, The high losses reflected their heavy use rather than fragility, with the heavy use leading to crew fatigue that contributed to the high accident rate.

Huey production reflected the course of the war in Vietnam, going from 20 per month in 1963, to 160 per month in 1967, and then back to 10 per month in 1973. Vietnam has been judged the "first helicopter war", and certainly the Huey remains a symbol of the conflict far more than any other weapon, from images of Hueys dropping troops into landing zones, to pictures of Hueys thrown off aircraft carriers during the frantic final evacuation.



* In 1965, Bell had experimented with a single twin-engine Model 208 "Twin Delta" Huey prototype, which was a UH-1D fitted with Continental XT67-T-1 engine module, consisting of two T72-T-2 turboshaft engined driving a common gearbox. This exercise was performed as an experiment using company funds.

In early 1968, Bell had discussions with the Canadian government and Pratt & Whitney Canada (PWC) that led to an agreement in 1969 to build a twin-engine version of the Model 205. Bell flew a UH-1D fitted with a new PWC "Twin Pac" engine, consisting of two of PWC's popular PT6 turbines driving a common gearbox, in 1969.

This prototype led to the production "Twin Huey" or "Model 212 / UH-1N", essentially a UH-1H fitted with the PWC T400-CP-400 (PT6T-3) Twin Pac, providing a total of 1,530 horsepower. Each turbine module of the Twin Pac could actually provide 900 horsepower each, but the rotor system couldn't deal with 1,800 horsepower. However, in the event of a failure of one of the turbines, the remaining operational turbine could be run at its full 900 horsepower output.

Bell began deliveries of the UH-1N to the US Air Force in 1970, which obtained 79 and used them for special operations. The US Navy and Marine Corps were particularly interested in the type, as the twin-engine configuration provided greater flight safety for overwater operations, and had obtained a total of 221 by 1978. Two standard Marine UH-1Ns were converted to "VH-1N" VIP transports, and six Model 212s were built new to this standard for the Corps as well.

The Canadian Armed Forces, which had backed development of the type, received their first Model 212 on 3 May 1971, with the last of 50 delivered about a year later. The CAF originally designated the type the "CUH-1N", but this was later changed to "CH-135".

Small quantities of the Model 212 have been sold to other military operators as well as commercial users. The enhanced safety provided by the Model 212's twin-engine configuration also proved to be an excellent selling point for commercial operators working in offshore gas and oil exploration.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   rotor width             14.69 meters        48 feet 2 inches
   footprint length        17.46 meters        57 feet 3 inches
   fuselage length         12.92 meters        42 feet 5 inches
   height                  4.53 meters         14 feet 10 inches

   empty weight            2,720 kilograms     6,000 pounds
   max loaded weight       4,535 kilograms     10,000 pounds

   maximum speed           205 KPH             125 MPH / 110 KT
   service ceiling         5,275 meters        17,300 feet
   range                   460 kilometers      285 MI / 250 NMI
   _____________________   _________________   _______________________

* The Bell Model 412 program was announced on 8 September 1978, with initial deliveries in January 1981. It is essentially a Model 212 with a four-blade composite rotor for smoother and more efficient flight. The rotor system can be folded for compact storage. It is powered by a PWC PT6T-3B-1 Twin Pac engine with a total of 1,310 horsepower. The Model 412 features crashworthy seats, fuel tanks, and landing gear, and the fuselage also features built-in maintenance steps and handholds to ease servicing in the field. It can carry up to 14 passengers, or six stretchers with attendants.

The initial 412 led to several improved variants:

Bell developed a prototype of an attack helicopter variant, the "Model 412AH", introduced in 1986. It featured a Lucas turret mounted under the nose and fitted with a single 12.7 millimeter (0.50 caliber) machine gun, and could also carry rockets and other stores. Little seems to have come of this exercise.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   rotor width             14.02 meters        46 feet
   footprint length        17.12 meters        56 feet 2 inches
   fuselage length         12.70 meters        41 feet 8 inches
   height                  3.48 meters         11 feet 5 inches

   empty weight            3,100 kilograms     6,835 pounds
   max loaded weight       5,400 kilograms     11,900 pounds

   maximum speed           260 KPH             160 MPH / 140 KT
   hover ceiling           3,100 meters        10,170 feet
   range                   745 kilometers      465 MI / 400 NMI
   _____________________   _________________   _______________________

Total sales by Bell of Model 412s amounted to some 530 by 1998. The Canadian Armed Forces have been a big customer, buying 100 Model 412HPs as the "CH-146 Griffon".


[6] MODEL 214

* In 1970, Bell announced the introduction of an improved derivative of the Model 205 / UH-1H to be designated the "Model 214 Huey Plus". The single Model 214 prototype featured the Lycoming T53-L-13 turboshaft engine with 1,400 horsepower; a new wide-chord "Nodomatic" rotor system with no teeter bar that could handle full horsepower of the engine; structural strengthening to permit higher load weights; and various detail changes.

The prototype led to the production "Model 214A", which was similar but had a more powerful Lycoming LTC4B-8D turboshaft engine with 2,930 horsepower. The Model 214A was demonstrated to the Iranians, and in late 1972 the Shah's government placed an order for 287 of the type for the Iranian Army, who named it the "Isfahan", after the town where the Iranian Army's helicopter training school was based. After this batch, the Iranian Army ordered six more Model 214As, while the Iranian Air Force ordered 39 Model 214Cs, which were similar but fitted for the SAR role. The Iranian Model 214s served in the country's war with Iraq in the 1980s.

* The Model 214A itself was difficult to distinguish from a Model 205, but Bell began to consider a "stretched" derivative with a "Twin Pac" type engine configuration and other much more visible changes. The company began discussions with the Shah's government for license production of the Model 214A and the new "Model 214ST (Stretched Twin)", but in 1979, the same year the first of three Model 214ST prototypes flew, the Shah's government was overthrown and the production scheme never happened.

Bell continued development of the Model 214ST anyway, redefining the "ST" suffix to stand for "Super Transport", leading to initial deliveries of the new variant in 1982. The Model 214ST has a modernized and more streamlined appearance than other versions of the Huey; features a "roll ring" built into the fuselage for crew protection; and is fitted with a glass-fiber rotor with titanium leading-edge strips and stainless steel end caps. It can carry a crew of two and up to 18 passengers.

The Model 214ST is fitted with twin GE T700 turbines providing a total of 3,250 horsepower, and can carry nearly 3,630 kilograms (8,000 pounds) of payload. It has proven popular in commercial service, particularly for offshore oil and gas exploration, and has been purchased by a number of foreign military services. The Iraqis also bought 45 Model 214STs in the late 1980s, and small numbers were sold to Brunei, Oman, Peru, Venezuela, and Thailand.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   rotor width             15.85 meters        52 feet
   footprint length        18.95 meters        65 feet 2 inches
   fuselage length         15.02 meters        49 feet 4 inches
   height                  4.85 meters         15 feet 2 inches

   empty weight            4,284 kilograms     9,445 pounds
   max loaded weight       7,940 kilograms     17,500 pounds

   maximum speed           255 KPH             160 MPH / 140 KT
   service ceiling         1,950 meters        6,400 feet
   range                   800 kilometers      500 MI / 435 NMI
   _____________________   _________________   _______________________

* Bell also developed a civil derivative of the Model 214A, the "Model 214B BigLifter", with modest changes including emergency escape windows in the cargo doors, an engine fire extinguishing system, and civilian avionics. It was offered for roles such as passenger transport, a "flying crane" with an external cargo hook, agricultural service, or firefighter.

The Model 214B was certified in early 1976, but there were few sales, with small numbers sold to Dubai, Ecuador, Oman, and the Phillipines. Production ended in 1981.



* The Huey proved popular in foreign service. Bell sold small quantities of UH-1Bs and UH-1Ds to Australia and Norway, and UH-1Hs for Canada and New Zealand. The Canadians used their "CUH-1Hs" (later "CH-118") for training. At least 55 UH-1Hs were also shipped to Turkey.

However, most foreign-service Hueys were license-built. Dornier of Germany built 352 UH-1Ds for the West German army, and AIDC in Taiwan built 118 UH-1Hs for the Nationalist Chinese army. IPTN of Indonesia has license-built the Model 412 as the "NBell-412".

Fuji Heavy Industries of Japan began license production of the Huey in 1962, producing at least 90 UH-1Bs and 50 UH-1Hs, mostly for the Japanese Self-Defense Forces but also for a few civil operators.

Fuji then went on to develop a unique Japanese variant of the UH-1H, appropriately designated "UH-1J". The UH-1J features an Allison T53-L-703 turboshaft engine with 1,800 horsepower, a vibration-reduction system, infrared countermeasures, and a night-vision-goggle compatible cockpit. First delivery of the UH-1J to the Self-Defense Forces was in 1993, with 78 delivered into 1998.

* The most enthusiastic alternate source for the Huey has been Agusta of Italy. Agusta obtained a license to build Model 204 Hueys in 1961, flying their first example on 10 May 1961, and then went on to produce the Model 205. Agusta-Bell Model 204s and 205s have been sold to a large number of nations, including Austria, Greece, Iran, Italy, Morocco, Oman, Saudi Arabia, Singapore, Spain, Sweden, Tanzania, Tunisia, Turkey, Yemen, Zambia, and Zimbabwe,

Agusta adopted a "customer is always right" attitude, and provided a wide range of auxiliary gear kits for customers. These kits included additional fuel tanks, rescue hoist, rotor brake, engine sand and dust filtering, engine winterization, fixed floats, emergency floatation gear, snow skis, and a number of weapons fits.

Agusta even supplied AB-204s fitted with a Rolls-Royce / Bristol Gnome H.1200 turboshaft with 1,200 horsepower, or a GE T58-GE-2 turboshaft with 1,325 horsepower. The company also developed prototypes of their own "Twin Hueys" based on AB-205s with dual Gnome H.1200 or Turbomeca Astazous engines, but these variants did not reach production status.

The company built a specialized maritime warfare variant of the Huey designated the "AB-204AS" (where "AS" stands for "Anti-Submarine" or "Anti-Surface Vessel"), fitted with search radar, dunking sonar, and the capability to carry homing torpedoes and other stores for maritime combat. This machine was sold to the navies of Italy, Spain, and Turkey.

* Agusta went on to license-build the Bell 212, and sold the type to Austria, Dubai, Italy, Lebanon, Morocco, Saudi Arabia, Somalia, Spain, Sudan, Yemen, and Zambia.

As a follow-up to the AB-204AS, the company produced a similar ASW variant of the Model 212, the "AB-212AS". Work on this version began in 1971, resulting in the flight of a prototype in 1973.

The AB-212AS resembles a standard Model 212 Twin Huey except for a prominent radome above the cockpit. Early production had a dome-shaped radome, while later production had a flatter "drum" radome, apparently reflecting different radar fits, with the current fit being the Ferranti SeaSpray radar. A winch hung outside the left side is standard equipment, and is used for handling the rotorcraft's Bendix ASQ-18 dipping sonar. Other changes include structural reinforcement, shipboard deck tiedown attachments, and corrosion protection.

The AB-212AS carries a crew of four in maritime combat operations, including pilot, copilot, and two systems operators. It is fitted with an all-weather flight control system, which provides both navigation and "hands-off" autopilot capabilities, and is integrated with the helicopter's search and targeting systems to pinpoint both helicopter and target positions. The AB-212AS is also fitted with a countermeasures suite.

In ASW operations, the AB-212AS can carry two Mk.44/46 or Moto Fides A-244/S homing torpedoes. For surface vessel attack operations, it can carry two Italian Marte Mk.2, British Sea Skua, or (obsolete) Aerospatiale AS-12 light antiship missiles. The AB-212AS can also be fitted with a TG-2 Teseo data link to provide guidance updates to the Italian Otomat ship or shore launched antiship missile.

Although the AB-212AS is optimized for the maritime combat mission, it also retains the ability to carry passengers and cargo, as well as perform SAR missions using its winch. It can accommodate four litters and a medical attendant for medevac operation, or up to seven passengers. The AB-212AS has been sold to Greece, Iran, Italy, Spain, Turkey, and Venezuela.

* Agusta began production of the Model 412 in 1981, and quickly came up with a multi-role military version designated the "AB-412 Grifone (Griffon)", which could be fitted for gunship, medevac, troop transport, or SAR roles. First flight of the prototype Griffon was in 1982, with initial delivery in 1983.

The Grifone differs from the standard production Model 412 in having crash-resistant seats, adding armor plating for pilot and copilot; high-impact landing gear; self-sealing fuel tanks; and permanent armament attachment points. Optional sensor and countermeasures systems can also be fitted.

Possible weapons fits include two 12.7 millimeter gun pods; two 25 millimeter Oerlikon cannon; two 19-round launchers for 81-millimeter SNORA unguided rockets; four or eight TOW missiles; air-to-air missile pods for Stinger and similar weapons; or four BAE Sea Skua antiship missiles. The Grifone can also accommodate six stretchers and two attendants, or up to 15 troops. Agusta has sold the Grifone to Dubai, Finland, Italy, Lesotho, Uganda, and Venezuela.



* With so many Hueys built, it is not surprising that several companies are offering update programs. Bell offers a UH-1H update designated the "UH-1HP Huey II", which involves modifying the Lycoming T53-L-13 engine up to T53-L-703 standard, giving it 400 more horsepower for a total of 1,800 horsepower; a new dynamic system, derived from that of the UH-1N and the Model 212, to handle the greater horsepower; and new avionics. The improved engine is more reliable, slightly more fuel efficient, and raises the payload from 450 kilograms (1,000 pounds) to 1,350 kilograms (3,000 pounds).

Global Helicopter has offered a "Huey 800" update, which replaces the UH-1H's TF3-L-13 engine with an LHTEC T800-800 turboshaft. The new engine has the same power output as the old, meaning no dynamic system updates are required, but the new engine is lighter, more reliable, and much more fuel-efficient.

UNC has offered a "UH-1/T700" update very similar to the Bell UH-1HP update, but replaces the T53-L-703 engine with a GE T700-GE-701C engine with 1,900 horsepower to provide improved fuel mileage.

* The US Marine Corps has kept their UH-1N Hueys up-to-date, adding countermeasures such as infrared jammers and chaff-flare dispensers, forward-looking infrared (FLIR) turrets in the nose, a cable cutter above the cockpit, new armament fits, and revised avionics.

The service is now working with Bell to update 100 Marine UH-1Ns to the new "UH-1Y" standard, with the first rolled out in late 2001. The UH-1Y upgrade is intended to extend the service life of the UH-1Ns, since many are about two-thirds of the way through their 10,000-hour design life, and to improve payload and performance. The upgrade includes:

The UH-1Y is stretched to accommodate the new hardware and preserve their center of balance. The improved Huey has 800 kilograms (1,760 kilograms) more payload capacity, and a top speed of 295 KPH (185 MPH) compared to a previous top speed of 200 KPH (125 MPH).

The UH-1Y upgrade program was part of a deal that also involved a parallel upgrade of 180 Marine AH-1W SuperCobra helicopter gunships to the new "AH-1Z" standard, with a high degree of commonality between the two updated aircraft. The first UH-1Y was rolled out in late 2001, and initial deliveries are scheduled for 2004.



* With so many Hueys built, there have of course been some unusual one-off special modifications of the type:



* Model 204 variants include:

* Model 205 variants include:

* Model 212 Twin Huey variants include:

* Model 412 variants include:

* Model 214 variants include:



* Although I have never seen a good number of the aircraft I write about, that is is certainly not the case for the Huey. I don't think I can remember a year for the last three decades or so when I haven't seen them flying around.

It is ironic, however, that although the Huey is one of the most heavily produced flying machines of the postwar era, it is hard to find information on it, and this writeup became something of a scavenger hunt. Helicopters just do not have that much sex appeal.

* Sources include:

* Revision history:

   v1.0   / 01 apr 01 / gvg
   v1.0.1 / 01 jan 02 / gvg / Added variant summary, plus minor tweaks.