UH-1N_Twin

UH-1N Iroquois
Marine UH-1Ns lifting from a field outside Baghdad on 10 April 2003.
Role	Multipurpose utility helicopter
Manufacturer	Bell Helicopter
First flight	April 1969
Introduced	October 1970
Primary users	United States Marine Corps Canadian Forces United States Navy United States Air Force
Developed from	UH-1H Iroquois
Variants	Bell 212 UH-1Y Venom

The Bell UH-1N Twin Huey is a medium military helicopter that first flew in April, 1969.¹ 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.

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.² The CF approved the development of the aircraft on 1 May 1968¹ and purchased 50 aircraft, with deliveries commencing in May 1971.³

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, Mendal 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 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 engines. As a result the United States military services ordered 294 Bell 212s under the designation UH-1N, with deliveries commencing in 1970.³

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".⁴

The Bell 412 is a further development of the Bell 212, the major difference being the composite four-blade main rotor.³

Design

The UH-1N's main rotor is powered by a PT6T-3 Turbo Twin Pac made up of two Pratt & Whitney Canada PT6T turboshaft engines. 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.³

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

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.⁵

Significant flights

Variants

U.S. variants

Foreign variants

Operators

Specifications (USMC UH-1N, as modified)

Data from USMC UH-1N Fact Sheet,¹⁸ The International Directiory of Military Aircraft, 2002-2003¹⁹

Twin Huey badges

Canadian CH-135 Twin Huey Gallery

CH-135 Twin Huey 135102 serving with the Multinational Force and Observers Sinai, Egypt, 1989.	CH-135 Twin Huey 135137 in the original blue-gray and green camouflage pattern worn by these aircraft prior to 1986/88.	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.	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 135103 after repainting at Bristol Aerospace in the in anti-IR olive and green scheme used on all non-SAR/ non-peacekeeping Twin Hueys after 1986/88. The aircraft was returned to the Aerospace Engineering Test Establishment at CFB Cold Lake, 1987.	CH-135 Twin Huey 135114 in the Canada Aviation Museum 09 October 2006. This aircraft is painted in the anti-IR camouflage scheme, but served its time painted yellow with 424 Transport & Rescue Squadron, CFB Trenton, Base Rescue Goose Bay and 444 Combat Support Squadron, CFB Goose Bay.

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