''For an overview of the whole Huey family of aircraft see Bell Huey ''

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 .

Development

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 Canadian government had not supported US involvement in Vietnam and had opposed US policies in southeast Asia, as well as accepting US draft dodger s. 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 Bell 412 is a further development of the Bell 212, the major difference being the composite four-blade main rotor. The UH-1N has also been developed into the upgraded, four-blade UH-1Y .

Design

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 212 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 and both captured by the British.

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 .

Significant flights

On 6 March 1972, Hendrick V. Gorick of the United States Navy Antarctic Development Squadron Six (VXE-6) jumped at an altitude of 20,500 ft (6,248 m) from a UH-1N helicopter. In doing so he set a record for parachute jumping over the Antarctic continent .

Variants

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 will replace theirs with the Common Vertical Lift Support Platform to support their ICBM activities.

VH-1N

VIP transport configuration

HH-1N

SAR variant.

;UH-1Y Venom

Essentially a massive 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.

Foreign 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 , Greece, Iran, Italy, 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.

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 .

CUH-1N Twin Huey

Original Canadian Armed Forces designation for the UH-1N utility transport helicopter.

Operators

ANG

* Angolan Air Force operates Bell 212s.

ARG

* Argentine Air Force operates Bell 212s from 1978.

* Argentine Army operates Bell 212s from 1976.

AUT

* Austrian Air Force operates Agusta-Bell 212s and Bell 212s from 1980.

BAN

* Bangladesh Air Force operates Bell 212s.

BHR

* Royal Bahraini Air Force operates Agusta-Bell 212s.

BOL

* Bolivian Air Force operates Bell 212s.

BRN

* Royal Brunei Air Force operates Bell 212s.

CAN

* 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

**VU32 - 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

* Canadian Coast Guard operates Bell 212s.

COL

* Colombian Air Force operates Agusta-Bell 212s.

* Colombian Army operates UH-1N and CH-135 versions.

* Colombian Navy operates Bell 212s.

* ''Policía Nacional de Colombia'' operates Bell 212s and CH-135s.

CRO

* Special Operations Battalion operates Agusta Bell 212s.

* Croatian Police operates Agusta Bell 212s.

ECU

* ''Fuerza Aérea Ecuatoriana'' operates Bell 212s.

GAB

*Gabonese Air Force

GER

* Luftwaffe former operator, three helicopters only

* German Federal Police operates Bell 212s.

GRE

* Hellenic Air Force operates Agusta-Bell 212s.

* Hellenic Army operates Agusta-Bell 212s.

* Hellenic Navy operates Agusta-Bell 212ASW/EW variants.

GUA

* ''Fuerza Aérea Guatemalteca'' operates Bell 212s.

GUY

*Guyana Defence Force operated Bell 212s from 1975 to 1990.

IRN

* Imperial Iranian Air Force operated Agusta-Bell 212s from 1978, Islamic Republic of Iran Air Force after 1979.

* Islamic Republic of Iran Navy operates Agusta-Bell 212ASW variants.

Iraq|1963

* Iraqi Navy operated Agusta-Bell 212ASW variant between 1984 and 2003

ISR

*Israeli Air Force operated Bell 212s.

ITA

* ''Aeronautica Militare '' operates Agusta-Bell 212s.

* ''Marina Militare '' operates Agusta-Bell 212ASW variants.

JAM

*Jamaica Defence Force operated three Bell 212s from 1973 to 1999.

JPN

*Japan Coast Guard operates Bell 212s.

LBN

*Lebanese Air Force operated Agusta-Bell 212s, aircraft are stored currently.

LBY

*Libyan Air Force operates Bell 212s.

MLT

*Armed Forces of Malta operates Agusta-Bell 212s with mixed crews on SAR duties by an Italian Technical Assistance Mission.

MAR

*Royal Moroccan Air Force operates Bell 212s.

PAN

*National Aeronaval Service

PER

*''Fuerza de Aviación Naval'' operates Agusta-Bell 212ASW variant.

PHI

*Philippine Air Force operates Bell 212s.

SAU

*Royal Saudi Air Force operates Agusta-Bell 212s.

SRB

*Serbian Police

SIN

*Republic of Singapore Air Force operated three Bell 212s for SAR missions . Helicopters were retired in 1985 and sold to Sri Lanka.

SOM

*Somali Air Corps operated Agusta-Bell 212s.

KOR

*Republic of Korea Air Force introduced Bell 212s in January 1971.

ESP

*Spanish Army has six Agusta-Bell 212s in use as of January 2010.

*Spanish Navy Air Arm operates 11 Agusta-Bell 212ASWs as of January 2010.

SRI

* Sri Lanka Air Force operates Bell 212s bought from Singapore.

SUD

*Sudanese Air Force operates Agusta-Bell 212s.

THA

*Royal Thai Army

*Royal Thai Navy operates Bell 212s.

TUN

*Tunisian Air Force operates Bell 212s.

TUR

* Turkish Army operates Agusta-Bell 212s.

* Turkish Navy operates Agusta-Bell 212ASW variant.

UGA

*Uganda People's Defence Force operates Agusta-Bell 212s.

ARE

UK

* Army Air Corps operates Bell 212s in Belize and Brunei .

USA

* United States Air Force

* United States Marine Corps

* United States Navy

URY

*''Fuerza Aérea Uruguaya'' operates Bell 212s.

YEM

*Yemeni Air Force operates Agusta-Bell 212s.

Aircraft on display

*Air Mobility Command Museum , Dover AFB , Delaware , United States

*Canada Aviation Museum , Ottawa, Ontario , Canada

*Marine Corps Base Camp Pendleton , San Diego County , California , United States

Specifications (USMC UH-1N, as modified)

Gallery

Image:BellCH-135TwinHuey135102.JPG|CH-135 Twin Huey 135102 serving with the Multinational Force and Observers Sinai, Egypt, 1989.Image:BellCH-135TwinHuey135137.JPG|CH-135 Twin Huey 135137 in the original blue-gray and green camouflage pattern worn by these aircraft prior to 1986/88.Image:BellCH135135TwinHuey.JPG|CH-135 Twin Huey 135135 in the early-style SAR markings, 1988. This aircraft was serving with Base Rescue Goose Bay and had formerly been assigned to 424 Transport & Rescue Squadron, CFB Trenton .Image:BellCH-135TwinHuey135127.JPG|CH-135 Twin Huey 135127 from Base Rescue Goose Bay in the later SAR scheme used after 1986/88.Image:BellCH-135TwinHuey135103A.JPG|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.Image:BellCH-135TwinHuey135103B.JPG|CH-135 Twin Huey 135103 after repainting in anti-IR olive and green scheme.Image:CH135TwinHueyBadge.JPG|CH-135 Twin Huey badge worn by some Canadian Forces air and ground crew, 1980sImage:408UTTHFltBadge.JPG|408 Tactical Helicopter Squadron UTTH Flight badge worn by CH-135 Twin Huey crews circa 1990. The badge is based on the shield of the province of Alberta