TheBell UH-1N Twin Huey is a mediummilitary helicopter designed and produced by the American aerospace manufacturerBell Helicopter. It is a member of the extensiveHuey family, the initial version was theCUH-1N Twin Huey (laterCH-135 Twin Huey), which was first ordered by theCanadian Forces in 1968.
Barely a year following initial discussions, the UH-1N performed itsmaiden flight in April 1969. Its procurement by the US military was initially controversial due to the high level of Canadian content, such as itsPratt & Whitney Canada PT6Tturboshaft engines. However, the acquisition was approved and the Twin Huey was quickly delivered to theUnited States Air Force and being sent to front line combat units inVietnam in October 1970. The following year, the Canadian Forces,United States Marine Corps, and theUnited States Navy all received their first examples; Bell was also quick to adapt the Twin Huey into a civilian helicopter, theBell 212, as well as the laterBell 412.[1]
The Twin Huey would see service in numerous conflicts, the first being theVietnam War, where they were commonly used to supportSpecial Forces reconnaissance missions. On the home front, they were used as the main utility helicopter at variousICBM launch sites, as well as operating as executive transports for carrying the US president and other high-ranking officials byMarine Helicopter Squadron One. USMC UH-1Ns were active during the2003 invasion of Iraq, providing reconnaissance, communications, andclose air support to ground forces. Overseas, UH-1Ns participated in theColombian armed conflict and theFalklands War. In the 2010s and 2020s, multiple operators were in the process of replacing the Twin Huey with newer helicopters, such as theBell UH-1Y Venom (a development of the UH-1N) and theAgustaWestland AW139.
The UH-1N was originally developed out of negotiations between theCanadian Forces (CF) andBell Helicopter on the topic of a new utility helicopter during 1968.[2] Specifically, the CF wanted it to be based on the stretched-fuselageBell 205, which the service already had experience of, but instead powered by a pair of engines for a higher level of safety. Furthermore, the selection of this engine, thePratt & Whitney Canada PT6Tturboshaft engine, was reportedly due to political factors. Its initial designation wasCUH-1N Twin Huey; later, the CF adopted a new designation system under which the rotorcraft was redesignatedCH-135 Twin Huey.[2][3] The CF approved the development of the rotorcraft on 1 May 1968,[1] a total of 50 CH-135s were procured, the deliveries of which commenced during May 1971.[4]
The US military quickly took an interest in the UH-1N and some officials were keen to quickly procure the type, yet the procurement came close to not happening. It was opposed by the chairman of theHouse Armed Services Committee at the time,L. Mendel Rivers, who disliked that the UH-1N's Pratt & Whitney Canada PT6T engines were produced in Canada. TheLiberal Canadian government of the time had not supported US involvement in Vietnam and had also opposed US policies inSoutheast Asia, as well as accepting USdraft dodgers. Rivers was also concerned that procuring the engines would result in atrade deficit situation with Canada.Congress only approved the Twin Huey purchase when it was assured that a US source would be found for the PT6T/T400 engines. Despite these concerns, the sale was permitted and theUnited States military services ordered 294 Bell 212s under the designationUH-1N, with deliveries commencing in 1970.[4]
Having secured multiple military customers, Bell Helicopters became interested in developing a commercial utility model for the civilian market; during 1971,type certification was given to theBell 212 by theFederal Aviation Administration (FAA).[2] Later on, homologation was obtained forinstrument flight rules (IFR) operations, for which appropriate avionics were fitted. During 1977, the company certified the Bell 212 for single-pilot IFR operations, making it the first helicopter in the world to obtain such certification.[2] Another key opportunity was the European market; Bell negotiated with the Italian helicopter manufacturerAgusta to produce theAB-212under license.[2] This model, the first examples of which was delivered in 1971, was broadly the same as their American-built counterparts, and were produced for both civilian and military operators. During 1976, theAB-212ASW, ananti-submarine warfare-orientated model, commenced production.[2]
TheBell 412 is a further development of the Bell 212, the major difference being the composite four-blade main rotor.[4] The UH-1N has also been developed into the upgraded, four-bladeUH-1Y, which was developed to replace the UH-1N in USMC service.[5]
Nighttime cockpit view during the military exercise Iron Fist, 2015Trio of UH-1N in 2019
The Bell UH-1N Twin Huey is a twin-engined medium-sizedmilitary helicopter primarily operated as a utility transport. Power is provided by a PT6T-3/T400 Turbo Twin Pac, comprising a pair ofPratt & Whitney Canada PT6turboshaft engines mounted side by side and driving a sharedgearbox and single output shaft.[2][6] These engines are capable of producing up to 1,342 kW (1,800 shp). In the event of a single power section failing, the remaining section can deliver 671 kW (900 shp) for up to 30 minutes or 571 kW (765 shp) continuously, enabling the UH-1N to maintain cruise performance at maximum weight.[4][2] It is capable of flight under instrument flight rules and in nighttime conditions.[6]
The UH-1N is often flown with a four-person crew, comprising two pilots and two crew chiefs; while in the air, these crew chiefs man the weapons, while one pilot functions as a navigator and the other actively flies.[7] The interior is normally outfitted with a 15-seat configuration, in which it can be flown by a single pilot and carry up to 14 passengers; in practice, rarely could the UH-1N actually carry this many unless also carrying limited fuel and equipment due to weight limitations and weather conditions.[6] When configured to carry cargo, the cabin has an internal capacity of 220 ft³ (6.23 m³). Up to six litters can be carried in a medical evacuation arrangement.[6] An external load of up to 5,000 lb (2,268 kg) can also be carried.[1] InUnited States Marine Corps (USMC) service, up to three radios would be installed in the cabin so that commanders could remain airborne while coordinating ground troops. The UH-1N was normally armed with a single .50 caliber machine gun on the helicopter's left side, while a 7.62 millimeter machine gun is mounted on the right side.[7]
To improve safety, a high level of redundancy is present across the UH-1N's key systems; these include duplicatehydraulic, electrical, and fuel systems. Fire suppression systems were also installed.[2] The USMC opted to modify a large number of their UH-1Ns with a stability control augmentation system, 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.[citation needed]
A Marine UH-1N on the flight line atNAS Whiting Field, Florida, 1982Special operations train using a UH-1N, 1983A USAF UH-1N during Exercise Wounded Eagle '83UH-1N in the Antarctic, 1988UH-1N deploy forHurricane Katrina relief effortsHoisting exercise in 2022
Starting in late 1970, mere months after receiving its first deliveries of the type, the USAF begun to re-equip the20th Special Operations Squadron inVietnam with UH-1Ns, supplementing and eventually replacing the single-engined UH-1F and UH-1P.[6] Armed withminiguns (or 40 mm grenade launchers) and rocket pods, and painted camouflage with no US markings and only a Green Hornet insignia, the UH-1N supportedSpecial Forces reconnaissance missions fromCam Ranh Bay.[8]
The first deliveries of the UH-1N to the U.S. Navy and USMC took place in 1971. In total, 205 UH-1Ns would be received, not including six VH-1N executive transports that were used to carry the US president and other high-ranking officials, operated byMarine Helicopter Squadron One.[9] Unlike in the CF, in US service, the UH-1N retained the official name "Iroquois" from the single–enginedUH-1 variants, although US service personnel refer to the aircraft as a "Huey" or "Twin Huey".[10]
In Canadian service, the CH-135 Twin Huey was regularly used as a tactical transport, moving troops and equipment around the forward areas of a combat zone;medevac flights were also conducted.[3] Further activities included VIP transport, search and rescue, and drug interdiction missions. CH-135s were deployed on multiple occasions to supportUnited Nationspeacekeeping missions in various regions, includingCentral America,Somalia, andHaiti.[3]
TheArgentine Air Force acquired eight Bell 212s during 1978.[2] During the 1982Falklands War, Argentina deployed a pair of Bell 212s to the airstrip atGoose Green where they performed general support duties, including the recovery of numerous downed pilots. By the end of the hostilities, both aircraft were still intact and flightworthy, but were captured and dismantled by the British troops.[11][2]
USMC UH-1Ns were deployed during the2003 invasion of Iraq; they were typically used to provide reconnaissance and communications support to ground troops. Multiple UH-1Ns were called upon to provide close air support during heavy fighting in theBattle of Nasiriyah.[12] In comparison with theBell AH-1 Cobra attack helicopter, the UH-1N had a wider field of fire with its weapons and thus played a useful role in close combat situations, commonly working in conjunction with Cobras.[7]
In August 2013, the USAF said they were close to finalizing a plan to sustain and modernize their UH-1Ns for the next six to ten years. It was intended to address flight and safety mandates, investigate modest improvements in capabilities, and reduce capability gaps. While the UH-1N had become one of the oldest platforms operated by the service, retaining it was viewed as having "minimal risk". Fleet-wide upgrades included night vision-compatible cockpit lighting, crash-worthy seats for flight engineers, and installation of a terrain-awareness warning system and traffic collision-avoidance device. The USAF was also in the process of acquiring ex-USMC UH-1Ns, possibly involving as many as 26 helicopters to either add them to USAF's active fleet or keep them in reserve.[15]
The USMC planned to retire the UH-1N by September 2014 after 43 years of service.Marine Light Attack Helicopter Squadron 773 was the last Marine squadron operating the type, their last deployment occurring in 2013, when two helicopters sailed on aRoyal Netherlands Navy ship for an African Partnership Station deployment. The UH-1N was replaced by the upgraded UH-1Y Venom; ten are remanufactured UH-1N airframes, after which the USMC decided to procure newly built airframes instead. By 2014, five unarmed HH-1Ns remained in use by the USMC until these were also replaced by UH-1Ys and retired in 2015, the only HH-1Ns remaining from 44 that were converted from 38 UH-1Ns and the six VH-1Ns.[9] The final combat deployment of USMC UH-1Ns was to Afghanistan in 2010. The service retired the UH-1N during a "sundown ceremony" atNaval Air Station Joint Reserve Base New Orleans on 28 August 2014.[19][20]
By March 2013, the USAF operated 62 UH-1N Twin Hueys, with 25 providing security atICBM sites, 19 stationed atJoint Base Andrews to evacuate Washington-based government officials in emergencies, and 18 used for testing and training. Since most were purchased in 1969, the USAF had sought a replacement.[21] The first requirements were issued in 2007, but the process was repeatedly delayed. On 24 September 2018, the USAF declared aBoeing/Leonardo submission of their MH-139 variant of theAgustaWestland AW139 the winner, beating out theSikorsky/Lockheed MartinHH-60U Black Hawk and theSierra Nevada Corporation upgraded UH-60L Force Hawk. Boeing was awarded an initial $375 million contract for four MH-139s, with 84 helicopters planned at a total $2.38 billion program cost. Initial deliveries were planned for 2021.[22][23]
Original Canadian Armed Forces designation for the UH-1N utility transport helicopter.[1][4]
CH-135 Twin Huey
Canadian version of the UH-1N.[1][4] 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 theNational Army of Colombia andColombian 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 byFARC 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 theCanada Aviation Museum inOttawa and one at theNational Air Force Museum of Canada atCFB Trenton.[24]
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 aFLIR turret. The USAF planned to replace their UH-1Ns with the Common Vertical Lift Support Platform to support the service's ICBM activities,[25] but also examined a life extension for their current fleet.[26]
A UH-1N replacement and upgrade as part of theH-1 upgrade program for the USMC, designed to coincide with a similar upgrade for theAH-1W attack helicopter to AH-1Z Viper standard, with common engines and other major systems.
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 BendixASQ-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.[28][29]
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 withBase Rescue Goose Bay and had formerly been assigned to 424 Transport & Rescue Squadron,CFB Trenton.
CH-135 Twin Huey 135127 fromBase 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 atCFB Cold Lake, 1987.
CH-135 Twin Huey 135103 after repainting in anti-IR olive and green scheme
^abcAir Force Public Affairs / Department of National Defence (6 April 2004)."Bell CH-135 Twin Huey". Archived fromthe original on 24 September 2012. Retrieved10 January 2013.
^"424 Squadron History".Air Force Public Affairs / Department of National Defence. 31 August 2010. Archived fromthe original on 13 November 2012. Retrieved10 January 2013.
^"430 Squadron".Air Force Public Affairs / Department of National Defence. 28 November 2008. Archived fromthe original on 22 May 2013. Retrieved10 January 2012.
^ab"444 Squadron History".Air Force Public Affairs / Department of National Defence. 11 April 2012. Archived fromthe original on 29 September 2012. Retrieved10 January 2012.
^"Utility Squadron VU 32".AEROWAREdesigns. 2012. Archived from the original on 6 August 2012. Retrieved10 January 2013.
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