Bell UH-1N Twin Huey
CH-135 Twin Huey
|U.S. Marine UH-1N helicopters take off from a field outside Baghdad in April 2003, during the Invasion of Iraq.|
|National origin||United States / Canada|
|First flight||April 1969|
|Primary users||United States Marine Corps
United States Navy
United States Air Force
|Developed from||Bell UH-1H Iroquois|
Bell UH-1Y Venom
The Bell UH-1N Twin Huey is a medium military helicopter that first flew in April, 1969. The UH-1N has a fifteen seat configuration, with one pilot and fourteen passengers. In cargo configuration the UH-1N has an internal capacity of 220 ft³ (6.23 m³). An external load of 5,000 lb (2,268 kg) can be carried by the UH-1N. The CUH-1N (later CH-135) Twin Huey was the original version, first ordered by the Canadian Forces.
Based on the stretched fuselage Bell 205, the Bell 212 was originally developed for the Canadian Forces (CF) under the designation CUH-1N Twin Huey. Later the CF adopted a new designation system and the aircraft was re-designated as the CH-135 Twin Huey. The CF approved the development of the aircraft on 1 May 1968 and purchased 50 aircraft, with deliveries commencing in May 1971.
The US military came very close to not procuring the Twin Huey. The purchase of the aircraft for US military use was opposed by the Chairman of the House Armed Services Committee at the time, L. Mendel Rivers. Rivers took this position because the aircraft powerplant, the Pratt & Whitney Canada PT6T was produced in Canada. The Liberal Canadian government of the time had not supported US involvement in Vietnam and had opposed US policies in southeast Asia, as well as accepting US draft dodgers. Rivers was also concerned that procurement of the engines would result in a negative trade deficit situation with Canada. Congress only approved the purchase when it was assured that a US source would be found for the PT6T/T400 engines. As a result the United States military services ordered 294 Bell 212s under the designation UH-1N, with deliveries commencing in 1970.
Unlike in the Canadian Forces, in US service, the UH-1N retained the official name "Iroquois" from the single engined UH-1 variants, although US service personnel refer to the aircraft as a "Huey" or "Twin Huey".
The UH-1N's main rotor is powered by a PT6T-3/T400 Turbo Twin Pac made up of two Pratt & Whitney Canada PT6 turboshaft power turbines driving a single output shaft. They are capable of producing up to 1,342 kW (1,800 shp). Should one engine fail the remaining engine can deliver 671 kW (900 shp) for 30 minutes or 571 kW (765 shp) enabling the UH-1N to maintain cruise performance at maximum weight.
The United States Marine Corps (USMC) modified a large number of their UH-1Ns with a Stability Control Augmentation System (SCAS) which provides servo inputs to the rotor head to help stabilize the aircraft during flight. This modification removed the gyroscopic "Stabilization Bar" on top of the main rotor head, instead relying on the computer system for stability.
Operational history 
Military service 
The United States Air Force employs UH-1Ns to fulfill its ICBM mission, providing a utility helicopter for transport between bases such as Minot AFB, Francis E. Warren AFB and Malmstrom AFB to missile launch sites in North Dakota, Montana, Wyoming, Nebraska, and Colorado. The UH-1N is also used by the 36th Rescue Flight (36 RQF) at Fairchild AFB, WA for conducting Search-and-Rescue (SAR) and medical evacuation missions.
During the 1982 Falklands War, the Argentine Air Force deployed two Bell 212s to Goose Green grass airstrip from where they performed general support duties including the recovery of many downed pilots. By the end of the hostilities both aircraft were still intact but were dismantled by the Argentinians. 
USMC UH-1Ns were used by the USMC during its 2003 invasion of Iraq. UH-1Ns provided reconnaissance, and communications support to Marine ground troops. They were also called upon to provide close air support during heavy fighting in Nasiriyah.
As of March 2013, the U.S. Air Force operates 62 UH-1N Hueys: 25 provide security at ICBM sites, 19 are stationed at Joint Base Andrews to evacuate Washington-based government officials in emergencies, and 18 are used for testing and training. Since most were purchased in 1969, the Air Force is seeking replacement of the Huey with the Common Vertical Life Support Platform (CVLSP). Possible candidates include the UH-72 Lakota, the AW139, and the UH-1Y Venom. The Air Force has been pushing for the CVLSP since 2006 and the program is not currently being funded, although officials are continuing to pursue the effort.
U.S. variants 
- UH-1N Iroquois
- Initial production model, used by the USAF, USN, and USMC. Over the years the primary operators, the USMC has developed a number of upgrades for the aircraft including improved avionics, defenses, and a FLIR turret. The USAF plans to replace their UH-1Ns with the Common Vertical Lift Support Platform to support the service's ICBM activities.
- VIP transport configuration
- SAR variant.
- UH-1Y Venom
- A UH-1N replacement and upgrade as part of the H-1 upgrade program for the USMC, designed to coincide with a similar upgrade for the AH-1W attack helicopter to AH-1Z Viper standard, with common engines and other major systems.
Canadian variants 
- CUH-1N Twin Huey
- Original Canadian Armed Forces designation for the UH-1N utility transport helicopter.
- CH-135 Twin Huey
- Canadian version of the UH-1N. Canada purchased 50 CH-135s with deliveries starting in 1971. The aircraft were retired from the Canadian Forces starting in 1996 and struck off strength in December 1999. 41 of the surviving CH-135s were acquired by the US government in December 1999 and transferred to the National Army of Colombia and Colombian National Police. At least one CH-135 was destroyed in combat. 135135 was transferred to the Colombian National Police and flown by the Dirección Antinarcóticos (DIRAN). It was destroyed on the ground by FARC rebels on 18 January 2002, following an incident in which it was forced down by gunfire. Two CH-135s are on display in museums, one at the Canada Aviation Museum in Ottawa and one at the National Air Force Museum of Canada at CFB Trenton.
Italian-built variants 
- Agusta-Bell AB 212
- Civil or military utility transport version. Built under license in Italy by Agusta.
- Agusta-Bell AB 121EW
- Electronic warfare version for Turkey.
- Agusta-Bell AB 212ASW
- Anti-submarine warfare, anti-shipping version of the AB 212 helicopter, built under license in Italy by Agusta. Operated by the Italian Navy, Hellenic Navy and Islamic Republic of Iran Navy, Peru, Spain, Turkey, and Venezuela.
- The AB-212ASW is a Model 212 Twin Huey with a prominent radome above the cockpit. Early production had a dome-shaped radome, while later production had a flatter "drum" radome. A left side winch is used for dipping the Bendix ASQ-18 sonar. Other changes include structural reinforcement for a gross weight of 11,197 lbs (5080 kg), ECM, shipboard deck tie-down attachments and corrosion protection. Armament is two Mk 44 or Mk 46 torpedoes or two depth charges in the ASW role and four AS.12 air-to-surface wire-guided missiles for the anti-shipping role.
- Colombian Air Force 
- Colombian Army
- Colombian Navy 
- Policía Nacional de Colombia operates Bell 212
Former operators 
- Canadian Forces operated CH-135 version from 1972 to 1998.
- 403 Helicopter Operational Training Squadron
- 408 Tactical Helicopter Squadron
- 422 Tactical Helicopter Squadron (disbanded 16 August 1980)
- 424 Transport & Rescue Squadron
- 427 Tactical Helicopter Squadron
- 430 Tactical Helicopter Squadron (430e Escadron Tactique d'Hélicoptères)
- 444 Combat Support Squadron
- VU 32 - Navy Utility Squadron
- Aerospace Engineering Test Establishment
- Base Flight Cold Lake
- Base Rescue Goose Bay
- Rotary Wing Aviation Unit, Canadian Contingent, Multinational Force and Observers, El Gorah Egypt, 1986-1990
Aircraft on display 
- Battleship Memorial Park, Mobile, Alabama, United States
- Canada Aviation Museum, Ottawa, Ontario, Canada
Specifications (USMC UH-1N, as modified) 
- Crew: 4 (Pilot, copilot, crew chief, gunner)
- Capacity: 6-8 combat-equipped troops, or equivalent cargo
- Length: 41 ft 8 in (12.69 m)
- Rotor diameter: 48 ft 0 in (14.6 m)
- Height: 14 ft 5 in (4.4 m)
- Disc area: 1,808 ft² (168.0 m²)
- Empty weight: 6,000 lb (2,721.5 kg)
- Loaded weight: 10,500 lb (4,762.7 kg)
- Useful load: 4500 lb (2038.0 kg)
- Max. takeoff weight: 10,500 lb (4,762.7 kg)
- Powerplant: 2 × Pratt & Whitney Canada T400-CP-400 turboshaft, 900 shp (671 kW), (total 1,250 shp) each
- Maximum speed: 130 knots (135 mph, 220 km/h)
- Cruise speed: 110 knots (126 mph, 207.3 km/h)
- Range: 248 nmi (286 mi, 460 km)
- Service ceiling: 17,300 ft (5,273 m)
- Rate of climb: 1,755 ft/min (8.9 m/s)
- Power/mass: hp/lb (W/kg)
- 2.75-inch (70 mm) rocket pods,
- GAU-16 .50 Cal. machine gun,
- GAU-17 7.62mm minigun or M240 7.62mm lightweight machine gun
CH-135 Twin Huey 135102 serving with the Multinational Force and Observers Sinai, Egypt, 1989.
CH-135 Twin Huey 135127 from Base Rescue Goose Bay in the later SAR scheme used after 1986/88.
CH-135 Twin Huey 135103 in special flight test markings. The aircraft was used by the Aerospace Engineering Test Establishment at CFB Cold Lake, 1987.
CH-135 Twin Huey badge worn by some Canadian Forces air and ground crew, 1980s
See also 
- Related development
- Related lists
- Mutza 1986, pp. 31-33.
- Air Force Public Affairs / Department of National Defence (6 April 2004). "Bell CH-135 Twin Huey". Retrieved 10 January 2013.
- Drendel 1983, pp. 14-17.
- Drendel 1983, p. 9.
- Eden 2004, p. 47.
- "H-83 bell 212 C/N 30834 - Helicopter Database". Helis.com. Retrieved 2013-01-10.
- FAA official magazine[dead link]
- Stout, Jay A. Hammer from Above, Marine Air Combat Over Iraq. Ballantine Books, 2005. ISBN 978-0-89141-871-9.
- UH-72 Lakota Could Be a Candidate for Air Force Duty - Defensemedianetwork.com, March 10, 2013
- USAF 2011 Budget justification, page 4-1
- Walker, RWR (June 2006). "Canadian Military Aircraft Serial Numbers Canadian Armed Forces CH-135 Twin Huey detailed list". Retrieved 2008-12-02.
- Green, William: Observers Aircraft, page 229. Frederick Warne Publishing, 1980. ISBN 0-7232-1604-5
- Wood, Derek: Jane's World Aircraft Recognition Handbook, page 490. Jane's Publishing Company 1985. ISBN 0-7106-0343-6
- "World Air Forces 2013". Flightglobal Insight. Retrieved 2013-23-01.
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- "Austrian Air Force Bell Twin Two-Twelve". Demand media. Retrieved 26-January-2013.
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- "RB AirForce Organization". Ministry of Defence, Brunei Darussalam. Retrieved 22-January-2013.
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- "Colombia - Navy (Armada República de Colombia [ARC])". globalsecurity.org. Retrieved 22-January-2013.
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- "türk deniz kuvvetleri". Retrieved 03-January-2013.
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- Hoyle Flight International 11–17 December 2012, p. 64.
- Air Force Public Affairs / Department of National Defence (24 March 2010). "403 Squadron Activated as Operational Training Squadron". Retrieved 10 January 2013.
- Air Force Public Affairs / Department of National Defence (22 Seeptember 2011). "408 Tactical Helicopter Squadron (THS) History". Retrieved 10 January 2013.
- Air Force Public Affairs / Department of National Defence (31 August 2010). "424 Squadron History". Retrieved 10 January 2013.
- Air Force Public Affairs / Department of National Defence (28 November 2008). "History of 427 Special Operations Aviation Squadron". Retrieved 10 January 2012.
- Air Force Public Affairs / Department of National Defence (28 November 2008). "430 Squadron". Retrieved 10 January 2012.
- Air Force Public Affairs / Department of National Defence (11 April 2012). "444 Squadron History". Retrieved 10 January 2012.
- AEROWAREdesigns (2012). "Utility Squadron VU 32". Retrieved 10 January 2013.
- Shaw, Robbie: Superbase 18 Cold Lake- Canada's Northern Guardians, page 86. Osprey Publishing, London, 1990. ISBN 0-85045-910-9
- Air Force Public Affairs / Department of National Defence (3 April 2012). "417 Combat Support Squadron - History". Retrieved 10 January 2013.
- 10 Tactical Air Group: Canadian Contingent Multinational Force and Observers Handbook (unclassified), page A-1. DND, Ottawa, 1986.
- "Israel Air Force - Aircraft Types". aeroflight.com. Retrieved 22-January-2013.
- "Jamaica Defence Force Aircraft". jdfmil.org. Retrieved 26-January-2013.
- "Philippine Air Force (PAF) Modernization - Helicopters". © 2000-2013 GlobalSecurity.org. Retrieved 10-January-2013.
- "30 Years of Helicopter Operations". mindef.gov.sg. Retrieved 22-January-2013.
- ""Huey" Helicopters Fly Final Flights for the U.S. Navy". ktvn.com. 06-Apr. 2009. Retrieved 20-January-2013.
- "US Navy Retires The Huey". DTN News. Retrieved 20-January-2013.
- Aircraft collection. ussalabama.com
- Canada Aviation Museum (undated). "Bell CH-135 “Twin Huey”". Archived from the original on 9 January 2009. Retrieved 2008-12-13.
- USMC (4 September 2008). "USMC UH-1N fact sheet". Archived from the original on 16 June 2007. Retrieved 14 October 2012.
- Frawley, Gerard: The International Directiory of Military Aircraft, page 33. Aerospace Publications Pty Ltd, 2002. ISBN 1-875671-55-2
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- Eden, Paul. "Bell 212/412". Encyclopedia of Modern Military Aircraft. London: Amber Books, 2004. ISBN 1-904687-84-9.
- Francillon, Rene, J. Vietnam: The War in the Air, New York: Arch Cape Press, 1987.
- Hoyle, Craig. "World Air Forces Directory". Flight International, Vol. 182, No. 5370. pp. 40–64. ISSN 0015-3710.
- Mesko, Jim, Airmobile: The Helicopter War in Vietnam. Squadron Signal Publications, 1984.
- Mutza, Wayne. UH-1 Huey in action. Carrolton, TX: Squadron/Signal Publications, 1986. ISBN 0-89747-179-2.
- Mutza, Wayne. UH-1 Huey in Colors. Carrolton, TX: Squadron/Signal Publications, 1992. ISBN 0-89747-279-9.
- Specifications for 204, 205 and 214 Huey Plus
|Wikimedia Commons has media related to: UH-1 Twin Huey|
- UH-1N page and UH-1 Huey history page on US Navy site
- UH-1N Huey fact sheet on USAF site
- The Bell UH-1 Huey at Greg Goebel's AIR VECTORS[dead link]