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94-782: The Bell UH-1N Twin Huey is a medium military helicopter designed and produced by the American aerospace manufacturer Bell Helicopter . It is a member of the extensive Huey family , the initial version was the CUH-1N Twin Huey (later CH-135 Twin Huey ), which was first ordered by the Canadian Forces in 1968. Barely a year following initial discussions, the UH-1N performed its maiden flight in April 1969. Its procurement by

188-607: A Dakota and act as "beaters" to drive the guerillas into stop groups landed by the helicopters. During the Troubles , the Provisional Irish Republican Army (IRA) became adept at avoiding conventional, fixed roadblocks and patrols. To prevent predictable patterns, the patrols were deployed by helicopter, known as Eagle Patrols, and were then able to disrupt the IRA's ability to move personnel and arms. In

282-503: A compromise being to give the passengers Kevlar lined seats but to leave the compartment for the most part unarmoured. Survivability is enhanced by redundancy and the placement of components to protect each other. For example, the Blackhawk family of helicopters uses two engines and can continue to fly on only one (under certain conditions), the engines are separated by the transmission and placed so that if attacked from any one flank,

376-553: A cost-cutting measure some nations and services have been tempted to use what are essentially commercial helicopters for military purposes. For example, it has been reported that China is carrying out a rapid enlargement of its assault helicopter regiments with the civilian version of the Russian Mil Mi-17 . These helicopters without armour and electronic counter measures will function well enough for training exercises and photo opportunities but would be suicidal to deploy in

470-516: A new variant may require re-certification. Again the basic process of type certifications is repeated (including maintenance programs). However, unaltered items from the basic design need not be retested. Normally, one or two of the original prototype fleet are remanufactured to the new proposed design. As long as the new design does not deviate too much from the original, static airframes do not need to be built. The resultant new prototypes are again subjected to flight tests. Upon successful completion of

564-513: A pair of engines for a higher level of safety. Furthermore, the selection of this engine, the Pratt & Whitney Canada PT6T turboshaft engine, was reportedly due to political factors. Its initial designation was CUH-1N Twin Huey ; later, the CF adopted a new designation system under which the rotorcraft was redesignated CH-135 Twin Huey . The CF approved the development of the rotorcraft on 1 May 1968,

658-740: A particular type design. ADs are used by the certifying authority to notify aircraft owners and operators of unsafe conditions and to require their correction. ADs prescribe the conditions and limitations, including inspection, repair, or alteration under which the product may continue to be operated. With increasing in-service experience, the type certificate holder may find ways to improve the original design resulting in either lower maintenance costs or increased performance. These improvements (normally involving some alterations) are suggested through service bulletins to an aircraft owners/operators as optional (and may be extra cost) items. The owner/operator shall exercise their discretion whether or not to incorporate

752-466: 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. To improve safety, a high level of redundancy is present across the UH-1N's key systems; these include duplicate hydraulic , electrical, and fuel systems. Fire suppression systems were also installed. The USMC opted to modify a large number of their UH-1Ns with a stability control augmentation system, which provides servo inputs to

846-803: A stabilised mount along with multi-function lasers capable of acting as laser rangefinder and targeting designators for weapons systems. By nature of the mission, the observation helicopter's primary weapons are its sensor suite and communications equipment. Early observation helicopters were effective at calling for artillery fire and airstrikes . With modern sensor suites, they are also able to provide terminal guidance to anti-tank guided weapons, laser-guided bombs and other missiles and munitions fired by other armed aircraft. Observation helicopters may also be armed with combinations of gun and rocket pods and sometimes anti-tank guided missiles or air-to-air missiles , but in smaller quantities than larger attack helicopters. Primarily, these weapons were intended for

940-548: A total $ 2.38 billion program cost. Initial deliveries were planned for 2021. Data from USMC UH-1N Fact Sheet , The International Directory of Military Aircraft, 2002-2003 General characteristics Performance Armament Related development Related lists Military helicopter Military helicopters play an integral part in the sea, land and air operations of modern militaries. Generally manufacturers will develop airframes in different weight/size classes which can be adapted to different roles through

1034-623: A total of 50 CH-135s were procured, the deliveries of which commenced during May 1971. 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 the House 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. The Liberal Canadian government of

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1128-454: A weakness. Emplaced insurgents and local sympathisers may observe such facilities covertly and gather intelligence on the schedules and routes of patrols and convoys. With this intelligence the insurgents can time their operations to avoid the COIN forces or plan ambushes to engage them, depending on their own tactical situation. Helicopters return a measure of surprise and tactical flexibility to

1222-452: Is a multi-purpose helicopter . A utility military helicopter can fill roles such as ground attack , air assault , military logistics , medical evacuation , command and control , and troop transport . While not essential to combat operations, helicopters give a substantial advantage to their operators by being a force multiplier . To maximise their impact, helicopters are utilised in a combined arms approach. High-intensity warfare

1316-605: Is also used by the 36th Rescue Squadron (36 RQS) at Fairchild AFB , Washington, for conducting search-and-rescue and medical evacuation missions, as well as the 459th Airlift Squadron based at Yokota Air Base in Japan. 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

1410-442: Is available. An STC is less expensive because the design change can be developed by a specialized design organization, a generally more flexible and efficient process than going through the original manufacturer. The STC defines the product design change, states how the modification affects the existing type design, and lists serial numbers of the aircraft affected. It also identifies the certification basis for regulatory compliance for

1504-646: Is characterized by large arrays of conventional armed forces, including mass formations of tanks , with significant air defenses. Helicopter armament and tactics were changed to account for a less-permissive flight environment. Anti-tank missiles , such as the SS.11 and the Aérospatiale SS.12/AS.12 were developed and mounted on French military helicopters. In turn, the United States adapted its BGM-71 TOW for firing from helicopters and eventually developed

1598-425: Is in compliance with applicable airworthiness requirements established by the national air law . For up to three seats, primary category aircraft certification costs around US$ 1 million, US$ 25 million for a general aviation aircraft and hundreds of millions of dollars for a commercial aircraft ; certification delays can cost millions of dollars and can decide a program's profitability. A type certificate (TC)

1692-446: Is issued by the aircraft operator and approved by the regulatory authority of the state of registry to maintain the airworthiness of the aircraft of the type owned by the operator. Maintenance tasks outlined in the maintenance program have to be scheduled and timely accomplished in order for the airworthiness certificate of their aircraft to remain valid. Other continuing airworthiness activities include additional tasks associated with

1786-568: Is issued for each aircraft that is properly registered if it conforms to its type design and ready for safe operation. The CoA is valid and the aircraft may be operated as long as it is maintained in accordance with the rules issued by the regulatory authority. The concept of a 'type certificate' was introduced by the "Air Navigation Regulations" published in May 1919 by the UK's Secretary of State for Air , Winston Churchill . The Buhl-Verville CA-3 Airster

1880-460: Is issued to signify the airworthiness of the approved design or "type" of an aircraft to be manufactured. The TC is issued by a regulatory authority, and once issued, the design cannot be changed unless at least part of the process for certification is repeated to cover the changes. The TC reflects a determination made by a regulatory authority that the type design is in compliance with airworthiness requirements. Examples of regulatory authorities are

1974-534: Is that personnel and cargo can be moved to and from locations without requiring a runway for takeoffs and landings. Cargo is carried either internally, or externally by slung load where the load is suspended from an attachment point underneath the aircraft. Personnel are primarily loaded and unloaded while the helicopter is on the ground. However, when the terrain restricts even helicopters from landing, personnel may also be picked up and dropped off using specialized devices, such as rescue hoists or special rope lines, while

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2068-624: The AGM-114 Hellfire . Meanwhile, the Soviet Union adapted the 3M11 Falanga missile for firing from the Mil Mi-24 . In the air, attack helicopters armed with anti-tank missiles, and one or more unarmed, or lightly armed scout helicopters operate in concert. The scout helicopter, flying at low level in a nap-of-the-earth approach, attempts to both locate the enemy armoured columns and to map out approaches and ambush positions for

2162-703: The Battle of Nasiriyah . In comparison with the Bell 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. The USAF employs the aging 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

2256-599: The Bell AH-1 . Modern helicopters have introduced modular systems which allow the same airframe to be configured for different roles, for example the Augusta Westland AW101 "Merlin" in Royal Navy service can be rapidly configured for ASW or transport missions in hours. To at the same time retain flexibility and limit costs, it is possible to fit an airframe for but not with a system, for example in

2350-589: The Bell UH-1Y Venom (a development of the UH-1N) and the AgustaWestland AW139 . The UH-1N was originally developed out of negotiations between the Canadian Forces (CF) and Bell Helicopter on the topic of a new utility helicopter during 1968. Specifically, the CF wanted it to be based on the stretched-fuselage Bell 205 , which the service already had experience of, but instead powered by

2444-534: The Colombian armed conflict . On 16 October 2013, a UH-1N crashed in the northern La Guajira department in a FARC -dominated area. 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 a Royal Netherlands Navy ship for an African Partnership Station deployment. The UH-1N

2538-679: The Combat search and rescue (CSAR) mission. Some services use a version of their operational helicopters, usually in the light class, for pilot training. For example, the British have used the Aérospatiale Gazelle both in operations and as a trainer. Some services also have an ab initio phase in training that uses very basic helicopters. The Mexican Navy has acquired a number of the commercially available Robinson R22 and R44 helicopters for this purpose. A utility helicopter

2632-697: The Mil Mi-28 N, the Kamov Ka-52 , and the AH-64D Longbow , incorporate sensors and command and control systems to relieve the requirement for scout helicopters. To enhance the combat endurance of these missile-armed helicopters, transport helicopters were used to carry technicians, reloads and fuel to forward locations. Establishing these forward arming and refuel points (FARP) at pre-arranged locations and times allowed armed or attack helicopters to re-arm and refuel, often with their engines running and

2726-743: The United States Navy all received their first examples; Bell was also quick to adapt the Twin Huey into a civilian helicopter, the Bell 212 , as well as the later Bell 412 . The Twin Huey would see service in numerous conflicts, the first being the Vietnam War , where they were commonly used to support Special Forces reconnaissance missions. On the home front, they were used as the main utility helicopter at various ICBM launch sites, as well as operating as executive transports for carrying

2820-563: The aftermath of the American invasion of Iraq helicopters have been used as aerial supply trucks and troop transports to prevent exposure to ambushes set by the Iraqi insurgency . Due to the cost and complexity of training and support requirements, insurgent forces rarely have access to helicopters. The major Western European helicopter manufacturers are Leonardo S.p.A. (formerly AgustaWestland ) and Eurocopter Group . In North America,

2914-611: The licensed production of those companies products, whilst building up their own ability to design and manufacture helicopters through a process of workshare and technology transfer. In India, Hindustan Aeronautics Limited is the main helicopter manufacturer for the Indian Armed Forces . In the Soviet planned economic system, the Mil and Kamov OKBs were responsible only for the design of helicopters. A re-organisation of

Bell UH-1N Twin Huey - Misplaced Pages Continue

3008-627: The 1960s, the development of the turboshaft engine and transistor technology changed the face of maritime helicopter aviation. The turboshaft engine allowed smaller helicopters, such as the Westland Wasp , to operate from smaller vessels than their reciprocating engine predecessors. The introduction of transistors allowed helicopters, such as the Sikorsky SH-3 Sea King , to be equipped with integral dunking sonar , radar and magnetic anomaly detection equipment. The result

3102-576: The 1982 Falklands War , Argentina deployed a pair of Bell 212s to the airstrip at Goose 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. USMC UH-1Ns were deployed during the 2003 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

3196-781: The A340-600 which is based on the Airbus A340-200 and the A340-300. Any additions, omissions or alterations to the aircraft's certified layout, built-in equipment, airframe and engines, initiated by any party other than the type certificate holder, need an approved supplementary ("supplemental" in FAA terminology) type certificate, or STC. The scope of an STC can be extremely narrow or broad. It could include minor modifications to passenger cabin items or installed instruments. More substantial modifications may involve engine replacement, as in

3290-664: The Blackhawk modifications to Cessna Conquest and Beechcraft King Air turboprops , or a complete role change for the aircraft, such as converting a B-17 or Stearman into an agricultural aircraft. STCs are applied due to either the type certificate holder's refusal (frequently due to economics) or its inability to meet some owners' requirements. STCs are frequently raised for out-of-production aircraft types conversions to fit new roles. Before STCs are issued, procedures similar to type certificate changes for new variants are followed, likely including thorough flight tests. STCs belong to

3384-432: The British, Spanish, and Italian navies, the larger helicopters form the main anti-submarine strength of carrier air wings. When operating from shore bases, the helicopters are used as anti-submarine pickets to protect against hostile submarines loitering outside military ports and harbours; their endurance and payload providing advantages over smaller helicopters. Soviet maritime helicopters, operating from its cruisers, had

3478-706: The COIN commander. Patrols need not start and end in the same place (the main entrance of the local compound), nor do supply convoys need follow the same roads and highways. During the Rhodesian Bush War , the Rhodesian military developed and refined " Fireforce " tactics, using small flights of light helicopters, the helicopters would be equipped as gunships to directly attack insurgents with aerial gunfire and also as either an airborne command/observation post or troop transport. Once contact had been established against enemy guerillas paratroopers would be dropped by

3572-548: The LZ. The advantage of air assault over an airborne assault is the ability of the helicopters to continually resupply the force during the operation, as well as to transport the personnel and equipment to their previous location, or a follow-on location if the mission dictates. The first reconnaissance and observation aircraft were balloons, followed by light airplanes, such as the Taylorcraft L-2 and Fieseler Fi 156 . As

3666-499: The STC holder and are generally more restrictive than type certificate changes. The TC holder remains responsible for the continued integrity of the approved aircraft type design and must continue to be the focal point for resolving issues that may require corrective action. This requires the continued capability, or access to a capability, of providing appropriate technical solutions for service difficulties or mandatory corrective action. If

3760-538: 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. The UH-1N saw combat service in

3854-535: The US Army's Boeing AH-64D Apache variants are all fitted to be able to take the Longbow radar system, but not enough sets have been bought to equip the whole force. The systems can be fitted to only those airframes that need it, or when finances allow the purchase of enough units. Most military helicopters are armoured to some extent; however, all equipment is limited to the installed power and lift capability and

Bell UH-1N Twin Huey - Misplaced Pages Continue

3948-709: The US military was initially controversial due to the high level of Canadian content, such as its Pratt & Whitney Canada PT6T turboshaft engines. However, the acquisition was approved and the Twin Huey was quickly delivered to the United States Air Force and being sent to front line combat units in Vietnam in October 1970. The following year, the Canadian Forces, United States Marine Corps , and

4042-503: The US president and other high-ranking officials by Marine Helicopter Squadron One . USMC UH-1Ns were active during the 2003 invasion of Iraq , providing reconnaissance, communications, and close air support to ground forces. Overseas, UH-1Ns participated in the Colombian armed conflict and the Falklands War . In the 2010s and 2020s, multiple operators were in the process of replacing the Twin Huey with newer helicopters, such as

4136-488: The US president and other high-ranking officials, operated by Marine Helicopter Squadron One . Unlike in the CF, 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". In Canadian service, the CH-135 Twin Huey was regularly used as a tactical transport, moving troops and equipment around

4230-686: The USAF had sought a replacement. The first requirements were issued in 2007, but the process was repeatedly delayed. On 24 September 2018, the USAF declared a Boeing / Leonardo submission of their MH-139 variant of the AgustaWestland AW139 the winner, beating out the Sikorsky / Lockheed Martin HH-60U Black Hawk and the Sierra Nevada Corporation upgraded UH-60L Force Hawk. Boeing was awarded an initial $ 375 million contract for four MH-139s, with 84 helicopters planned at

4324-672: The United Kingdom's Civil Aviation Authority (CAA), the U.S. Federal Aviation Administration (FAA), the European Aviation Safety Agency (EASA), Transport Canada , Brazil’s Agência Nacional de Aviação Civil and the Civil Aviation Administration of China (CAAC). When changes are needed to an airframe or on-board equipment, there are two options. One is to initiate a modification by the type design holder (manufacturer), and

4418-660: The United States to rescue downed aircrews and injured personnel in remote areas of the China Burma India Theater , from April 1944 until the war's end. The use of helicopters for rescue during combat increased during the Korean War and the Algerian War . In the Vietnam War the USAF acquired Sikorsky S-61R (Jolly Green Giant) and Sikorsky CH-53 Sea Stallion (Super Jolly Green Giant) helicopters for

4512-612: The additional role of guidance of the cruisers' long range anti-shipping missiles. Maritime helicopters are navalised aircraft for operation from ships. This includes enhanced protection against salt water corrosion , protection against ingestion of water, and provision for forced ditching at sea. As helicopters came into military service, they were quickly pressed into service for search and rescue and medical evacuation . During World War II, Flettner Fl 282s were used in Germany for reconnaissance , and Sikorsky R-4s were used by

4606-444: The air, these crew chiefs man the weapons, while one pilot functions as a navigator and the other actively flies. 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. When configured to carry cargo,

4700-462: The aircraft hovers overhead. Air assault is a military strategy that relies heavily on the use of transport helicopters. An air assault involves a customized assault force that is assembled on the pick-up zone and staged for sequential transport to a landing zone (LZ). The idea is to use the helicopters to transport and land a large number of troops and equipment in a relatively short amount of time, in order to assault and overwhelm an objective near

4794-452: The applicable Minimum Operating Performance Standards (MOPS) applicable to that sub-assembly. MOPS are published by expert industry groups such as: RTCA Inc., EUROCAE, and SAE. When aircraft are produced to meet a given TC, each one need not be tested as rigorously but the confidence demonstrated by the TC is conferred, when the aircraft has been assigned a certificate of airworthiness (CoA). A CoA

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4888-420: The applicant firm also draws up maintenance program to support continuous airworthiness after approval of the design. The program is drawn with inputs from tests results and also from initial customers' engineering departments. The proposed maintenance program is submitted to the regulators for comment and approval. After successful completion of ground and flight tests, along with an approved maintenance program,

4982-469: The applicant would have to change the design as a result of changed regulation. An initial design sample known as a prototype is built. This refers to either the aircraft, the engines or the propeller, depending on the basis of the certification. For the purpose of illustration, the discussion shall be limited to the aircraft. Normally a few prototypes are built, each subject to different tests. The prototypes are first used for ground and system tests. One of

5076-456: The assault role in actual combat situations. The intention of China appears to be to retrofit these helicopters with locally produced electronics and armour when possible, freeing available funds to allow rapid creation of enough regiments to equip each of its Group Armies , allowing a widespread buildup of experience in helicopter operations. Attack helicopters are helicopters used in the anti-tank and close air support roles. The first of

5170-427: The attack helicopters. Late-model scout helicopters include laser designators to guide missiles fired from the attack helicopters. After finding a target, the scout helicopter can locate it and then direct the attack helicopter's missile where to fire. The attack helicopters have only to rise from cover briefly to fire their missiles before returning to a concealed location. Late-development of attack helicopters, such as

5264-509: The bulletins and report the decision to the regulatory authority of the state of the aircraft registry. Sometimes SBs can become mandated by relevant ADs. Often the basic design is enhanced further by the type certificate holder. Major changes beyond the authority of the service bulletins require amendments to the type certificate. For example, increasing (or decreasing) an aircraft's flight performance, range and load carrying capacity by altering its systems, fuselage, wings or engines resulting in

5358-416: The cabin has an internal capacity of 220 ft³ (6.23 m³). Up to six litters can be carried in a medical evacuation arrangement. An external load of up to 5,000 lb (2,268 kg) can also be carried. In United 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

5452-477: The capability of the early helicopters was as plane guard - tasked with the recovery of pilots who had ditched near an aircraft carrier . As helicopter technology matured with increased payload and endurance , anti-submarine warfare (ASW) was added to the helicopter's repertoire. Initially, helicopters operated as weapons delivery systems, attacking with air-launched torpedoes and depth charges based on information provided by its parent and other warships. In

5546-526: The certification program, the original type certificate is amended to include the new variant (normally denoted by a new model number additional to the original type designation). Typical examples are; the Boeing 737NG (737-600, 737-700, 737-800 and 737-900) which replaced the 737 Original family (737-100 and 737-200) and the 737 Classic family (737-300, 737-400 and 737-500) and the Airbus A340-500 and

5640-514: The counter-reconnaissance fight—to eliminate an enemy's reconnaissance assets—but they can also be used to provide limited direct fire support or close air support. Among the first practical uses of helicopters when the Sikorsky R-4 and R-5 became available to British and American forces was deployment from navy cruisers and battleships, at first supplementing and later replacing catapult-launched observation aircraft . Another niche within

5734-428: The design change. The TC implies that aircraft manufactured according to the approved design can be issued an airworthiness certificate . To meet those requirements the aircraft and each sub-assembly must also be approved. For example, in the U.S. these sub-assemblies must meet requirements in the applicable Technical Standards Order (TSO). To meet those requirements the design documents are examined for compliance with

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5828-849: The engine on that flank acts to protect the transmission and the engine on the other side from damage. Aviation electronics, or avionics , such as communication radios and navigation aids are common on most military helicopters. Specialized avionics, such as electronic countermeasures and identification friend or foe systems, are military specific systems that can also be installed on military helicopters. Other payload or mission systems are installed either permanently or temporarily, based on specific mission requirements; optical and IR cameras for scout helicopters, dunking sonar and search radar for anti-submarine helicopters, extra radio transceivers and computers for helicopters used as airborne command posts . Armour, fire suppression, dynamic and electronics systems enhancements are invisible to casual inspection; as

5922-416: 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. It is capable of flight under instrument flight rules and in nighttime conditions. The UH-1N is often flown with a four-person crew, comprising two pilots and two crew chiefs; while in

6016-406: The final approval of such documents (after the required comments and amendments in order to fulfill the laws), becomes the basis of the certification. The firm follows it and draws a proposed timetable of actions required for certification tests. With the application, the regulations to be applied will usually be frozen for this application for a given amount of time in order to avoid a situation where

6110-536: 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, the AB-212ASW , an anti-submarine warfare -orientated model, commenced production. 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

6204-504: The first military helicopters became available, their ability to both maneuver and to remain in one location made them ideal for reconnaissance. Initially observation helicopters were limited to visual observation by the aircrew, and most helicopters featured rounded, well-glazed cockpits for maximum visibility. Over time, the human eye became supplemented by optical sensor systems. Today, these include low light level television and forward looking infrared cameras. Often, these are mounted in

6298-410: The forward areas of a combat zone; medevac flights were also conducted. Further activities included VIP transport, search and rescue, and drug interdiction missions. CH-135s were deployed on multiple occasions to support United Nations peacekeeping missions in various regions, including Central America , Somalia , and Haiti . The Argentine Air Force acquired eight Bell 212s during 1978. During

6392-476: The frames outlined in a TC data sheet, and each given a serial number (a "series aircraft"). As the aircraft enters into service, it is subject to operational wear and tear which may cause performance degradations. The set of processes by which an aircraft, engine, propeller or part complies with the applicable airworthiness requirements and remains in a condition for safe operation throughout its operating life called continuing airworthiness . A maintenance program

6486-486: The helicopter industry in Russia created Russian Helicopters , a holding company to bring together Mil, Kamov, and other helicopter manufacturing and maintenance plants. Type certification A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design ( type design ). Certification confirms that the aircraft of a new type intended for serial production

6580-452: The holder is no longer capable or if the TC is transferred to another holder a regulatory authority should take appropriate action in accordance with the national legislation. In the case of the TC being transferred to another holder the new holder shall be capable of fulfilling the TC holder responsibilities in following ADs and providing technical support to keep the type design current with the applicable airworthiness requirements, even after

6674-486: The installation of mission specific equipment. To minimise development costs the basic airframes can be stretched and shortened, be updated with new engines and electronics and have the entire mechanical and flight systems mated to new fuselages to create new aircraft. For example, the Bell UH-1 Iroquois (known as the "Huey") has given rise to a number of derivatives through stretching and re-engining, including

6768-414: The limits installed equipment places on useful payload. The most extensive armour is placed around the pilots, engines, transmission, and fuel tanks. Fuel lines, control cables and power to the tail rotor may also be shrouded by Kevlar armour. The most heavily armoured helicopters are attack, assault and special forces helicopters. In transport helicopters the crew compartment may or may not be fully armoured,

6862-504: The maintenance program and design changes to be accomplished via: Sometimes during service, the aircraft may encounter problems that may compromise the aircraft's safety, which are not anticipated or detected in prototype testing stages. The aircraft design is thus compromised. The regulators will now issue an airworthiness directive to the type certificate holder and to all owners globally. The directives normally consists of additional maintenance or design actions that are necessary to restore

6956-451: The maximum size of the helicopters and the minimum size of the ships. Increasing miniaturisation of electronics, better engines and modern weapons now allow even the modern, destroyer-based, multi-role helicopter to operate nearly autonomously in the ASW, anti-shipping, transport, SAR and reconnaissance roles. Medium- and large-sized helicopters are operated from carriers and land bases. In

7050-775: The modern attack helicopters was the Vietnam era Bell AH-1 Cobra , which pioneered the now classic format of pilot and weapons officer seated in tandem in a narrow fuselage, chin mounted guns, and rockets and missiles mounted on stub wings. To enable them to find and identify their targets, some modern attack helicopters are equipped with very capable sensors such as a millimeter wave radar system. Transport helicopters are used for transporting personnel (troops) and cargo in support of military operations. In larger militaries, these helicopters are often purpose-built for military operations, but commercially available aircraft are also used. The benefit of using helicopters for these operations

7144-412: The other is to request a third party Supplemental type certificate (STC). The choice is determined by considering whether or not the change constitutes a new design (i.e. introduces risk not considered in the first type design). If so, then type design holder must develop and approve a modification to the type design. If the regulatory authority agrees the change does not introduce new risk, the STC option

7238-423: The production of the aircraft type has stopped but many out-of-production aircraft continue useful lives. STCs are also bound by the same rules. When the holder decides to stop supporting the aircraft type without the transfer of TC holder responsibilities, the TC is returned to the issuing regulatory authority and the remaining aircraft fleet can be grounded by the current states of registry until further decisions on

7332-399: The prototype is approved, and the firm is granted the TC for the prototype (as understood that it should include all furnished equipment for its intended role). The legal term for the firm is now the "type certificate holder". Subsequently, the prototype now serves as a template for serial aircraft production and the aircraft rolling out of the factory should be identical to the prototype within

7426-548: The prototypes (known as the "static airframe") is subject to destructive testing, i.e., the prototype is subject to stress beyond normal and abnormal operations until destruction. The test-results are compared with initial submitted calculations to establish the ultimate structural strength. Other prototypes will undergo other systems tests until the satisfaction of the regulators. With all ground tests completed, prototypes are made ready for flight tests. The flight tests are flown by specially approved flight test pilots who will fly

7520-404: The prototypes to establish the ultimate flight limits which should be within the airworthiness rules. If a long range airliner is tested, the flight tests may cover the whole world. Tests may also cover different environments - high and low altitude, freezing and hot climates, and so on, to confirm correct performance throughout the aircraft's design envelope . In parallel with aircraft testing,

7614-424: 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. Starting in late 1970, mere months after receiving its first deliveries of the type, the USAF begun to re-equip the 20th Special Operations Squadron in Vietnam with UH-1Ns, supplementing and eventually replacing

7708-431: The rotors still turning, and to quickly return to the front lines. In counter-insurgency (COIN) warfare, the government force establishes its presence in permanent or temporary military bases from which to mount patrols and convoys. The government forces seek to deter the insurgent forces from operating, and to capture or kill those that do. The operation of forces from fixed bases linked by a fixed network of roads becomes

7802-581: The sale was permitted and the United States military services ordered 294 Bell 212s under the designation UH-1N , with deliveries commencing in 1970. 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 the Bell 212 by the Federal Aviation Administration (FAA). Later on, homologation

7896-458: The single-engined UH-1F and UH-1P. Armed with miniguns (or 40 mm grenade launchers) and rocket pods, and painted camouflage with no US markings and only a Green Hornet insignia, the UH-1N supported Special Forces reconnaissance missions from Cam Ranh Bay . 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

7990-491: The three primary manufacturers are Boeing ( Boeing Vertol and McDonnell Douglas ), Bell Helicopter and Sikorsky Aircraft . In Japan, the three main manufacturers of helicopters are the aviation arms of the Japanese conglomerates Mitsubishi , Kawasaki and Fuji Heavy Industries . These companies initially followed a business model based on forming strategic partnerships with foreign, usually American, companies with

8084-527: The time had not supported US involvement in Vietnam and had also opposed US policies in Southeast Asia , as well as accepted US draft dodgers . Rivers was also concerned that procuring the engines would result in a trade 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,

8178-399: The type's airworthiness. Compliance is mandatory and thus if an operator does not comply with an AD, then the datum aircraft is not considered airworthy and further operation of the affected aircraft type would be unlawful , making the operator liable to legal action by the relevant national aviation authority, and rendering null-and-void any of the operator's insurance policies relating to

8272-479: The type, such as hull loss and accident third party coverage. ADs may also be raised with changes of the local or global aviation rules and requirements, e.g., the requirement to fit armored cockpit doors for all passenger airliners after the September 11 attacks . The certifying authority issues an AD when an unsafe condition is found to exist in a product (aircraft, aircraft engine, propeller, or appliance) of

8366-592: The upgraded, four-blade UH-1Y , which was developed to replace the UH-1N in USMC service. The Bell UH-1N Twin Huey is a twin-engined medium-sized military helicopter primarily operated as a utility transport. Power is provided by a PT6T-3/T400 Turbo Twin Pac, comprising a pair of Pratt & Whitney Canada PT6 turboshaft engines mounted side by side and driving a shared gearbox and single output shaft. These engines are capable of producing up to 1,342 kW (1,800 shp). In

8460-543: Was an aircraft able to more quickly respond to submarine threats to the fleet without waiting for directions from fleet vessels. Today, maritime helicopters such as the Sikorksy SH-60 Seahawk and the Westland Lynx are designed to be operated from frigates , destroyers and similar size vessels. The desire to carry and operate two helicopters from frigate- and destroyer-sized vessels has affected

8554-590: Was obtained for instrument 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. Another key opportunity was the European market; Bell negotiated with the Italian helicopter manufacturer Agusta to produce the AB-212 under license . This model,

8648-403: 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. The final combat deployment of USMC UH-1Ns

8742-537: Was the first aircraft to receive a type certificate in the US, (i.e. A.T.C. No. 1) issued by the Aeronautics Branch of the Department of Commerce on March 29, 1927. Initially, the applicant design organisation submits documents to their local aviation regulating body, detailing how the proposed aircraft type design would fulfill the airworthiness requirements. After investigations by the regulator,

8836-486: Was to Afghanistan in 2010. The service retired the UH-1N during a "sundown ceremony" at Naval Air Station Joint Reserve Base New Orleans on 28 August 2014. By March 2013, the USAF operated 62 UH-1N Twin Hueys, with 25 providing security at ICBM sites, 19 stationed at Joint Base Andrews to evacuate Washington-based government officials in emergencies, and 18 used for testing and training. Since most were purchased in 1969,

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