The UH-1N is a twin-engine helicopter that is otherwise similar to the UH-1H. The UH-1Ns are widely used in a transport, airborne battlefield command and control, troop insertion/extraction, fire support coordination, medical evacuation, search and rescue, armed escort/visual reconnaissance or utility roles throughout the Navy and Marine Corps. The Huey provides utility combat helicopter support to the landing force commander during ship-to-shore movement and in subsequent operations ashore. Air Force Space Command is the Air Force's largest operator of UH-1N Huey helicopters, responsible for missile operations support and security. The UH-1N light-lift Air Force utility helicopter is used for airlift of emergency security and disaster response forces, medical evacuation, security surveillance of off-base movements of nuclear weapons convoys and test range areas during launch conditions. It is also used for space shuttle landing support, priority maintenance dispatch support, and search and rescue operations. Other uses include airlift of missile support personnel, airborne cable inspections and distinguished visitor transport.

Easy change mission packages allow the UH-1N to be configured for Close in Fire Support, Supporting Arms Coordination, Forward Air Control, Command and Control, Special Insert and Extraction, Troop Transport, Medical Evacuation, Search and Rescue, and all types of assault support. The aircraft can be outfitted to support operations such as command and control with a specialized communication package (ASC-26), supporting arms coordination, assault support, medical evacuation for up to six litter patients and one medical attendant, external cargo, search and rescue using a rescue hoist, reconnaissance and reconnaissance support, and special operations using a new navigational thermal imaging system mission kit.

While the UH-1N shared the fuselage of the UH-1H, the primary difference was in the engines. The Pratt & Whitney PT6T-3 Turbo Twin-Pac power plant provided 1,800 horsepower for the UH-1N, versus the Lycoming T53-L-13 in the UH-1H, which provided 1,400 horsepower. Compared to the H-model, the N-model was longer at 57 feet, 3 ¼ inches, compared to 44 feet, 7 inches and slightly taller at 14 feet, 4 ¾ inches to 13 feet, 5 inches for the UH-1N. The main rotor diameter on the UH-1N was only 2 ¼ inches wider than the UH-1H with its rotor diameter of 48 feet. The Model 212 weighed 5,549 pounds empty and 11,200 loaded, compared to 5,090 and 9,500 pounds respectively for the Model 205. Maximum speeds for the two aircraft only varied 4mph with the UH-1H faster at 130mph. It also had the longer range at 357, compared to 273 miles for the UH-1H. The service ceiling of 17,400 feet for the UH-1N exceeded the UH-1H's 12,700-foot ceiling. Both aircraft were rated for a maximum of 13 people.

Bell developed the Model 212, or UH-1N, for the Canadian market, but US military orders far exceeded the initial 50 from Canada. The first American UH-1H entered service in 1970 and the Canadian version, designated CUH-1N, in the following year. The Air Force ordered this "Twin Pac" engine improved utility version for general utility/transport duties. In 1971 deliveries of this latest model to the Navy and Marine Corps began. A total of 212 were delivered, six in VH-1N executive transport configuration.

The UH-1N is capable of flight in instrument and night time conditions. The crew complement is normally two (pilot and copilot), but may be flown single-pilot, or with the addition of a flight engineer, depending on weather and mission requirements. Entrance to the passenger cargo area is through two sliding doors, one on each side of the aircraft. The sliding doors permit over-sized items to be loaded across the cabin. The UH-1N can accommodate up to 11 passengers. For medical evacuation and ambulance service, litter racks are installed in the cab to serve six patients and one medical attendant.

In September 1970 the first UH-1N student class arrived at Hurlburt Field, and the 1st SOW embarked on UH-1N operations and training which spanned a 15-year period. The final Hurlburt training class concluded June 23, 1971, when that function was transferred to the Military Airlift Command at Hill AFB, Utah. From then on, UH-1N crews concentrated on proficiency training at home and on exercises which were a "way of life" for the Huey people and the rest of the wing. A partial listing of these exercises include: Cabin Light IV at Fort Bragg, N.C., in 1971; Brave Shield I at Fort Stewart, Wash., in 1972; Exotic Dancer V, with ship-to-shore airlifts by the UH-1Ns in 1972; Flintlock V in Denmark in 1972; Brass Key II, at Fort Bragg in 1973; Green Flag I at Hurlburt Field in 1976; Blue Flag 77-3 and Bold Eagle 78 on Eglin Reservation in 1977; Solid Shield 80 in the Southeast U.S. in 1980; Red Flag 81-1 at Nellis AFB, Nev., in 1980; Ocean Venture 81 in the Caribbean area in 1981; and Granite Scar II on the Eglin Reservation in 1983.

While five UH-1Ns were deployed to Nellis AFB for Exercise Red Flag 81-1, a major fire occurred Nov. 21, 1980 at the MGM Grand Hotel in Las Vegas. Early in the morning after night operations, the 20th Special Operations Squadron crews returned to quarters in Las Vegas. Alerted to a call for assistance, they immediately returned to Nellis. Less than 45 minutes after notification, the crews were airborne to the fire scene. They operated from the hotel parking lot and transported firemen, rescue squads, paramedics and medical and rescue supplies to the hotel roof and removed people trapped by the fire. In 13 hours involving 31 shuttles, members of the 20th SOS saved five lives by evacuating critically injured people. After the fire was controlled, they removed 56 bodies from the hotel roof.

The 317th SOS inactivated April 30, 1974. A month earlier, the last two 1st SOW UH-1N helicopters of the squadron had been transferred to K.I. Sawyer AFB, Mich. This left the wing without any Hueys, or a squadron home for the aircraft. But that was rectified with the activation of the 20th SOS Jan. 1, 1976. The 20th inherited one UH-1N, which had arrived at Hurlburt Aug. 28, 1975; however, it was the end of June before the second Huey arrived. Three more joined the 20th before the end of the 1976 to give the squadron half of its six authorized UH-1Ns. It took almost a year and a half for Hurlburt to get all six Hueys since the sixth didn't arrive until the second quarter of 1977. Those six were the complement of UH-1N helicopters for the 20th SOS and 1st SOW until one crashed at sea in 1984 and the rest of the force transferred Oct. 1, 1985.

Rapid worldwide mobility has been a hallmark of the 1st SOW. Modifying aircraft for in-flight refueling providing the wing AC- and MC-130s deployment capability limited only by crew endurance. However, the short range, low-speed helicopters realistically couldn't deploy intercontinentally even with in-flight refueling. This required a new tactic, nicknamed Coronet Chopper, which the wing perfected in the early 1980s. It involved airlifting the UH-1Ns in large cargo aircraft, such as the C-5. By dismantling the Hueys to a certain extent, a C-5 could carry four anywhere in the world in a minimum amount of time, or a C-141B could rapidly deploy three.

In 1983, the 1st SOW and UH-1Ns embarked on their most visible mission - Operation Bahamas and Turks (Operation BAT). The objective was to curb illegal drug smuggling from South American through the Bahamas into south Florida. Two helicopters were deployed to the islands for what stretched into a period of almost two a half years, from May 1983 to September 1985. The UH-1Ns airlifted police and drug enforcement agents where needed to apprehend drug runners. In January 1984, one of the BAT aircraft suffered a two-engine failure and crashed at sea, killing three 20th SOS crewmen. While Operation BAT placed a severe strain on squadron resources, it provided excellent, high-stress training. Also on the positive side, the 20th SOS flew more than 1,100 sorties resulting in the capture of more than $1.5 billion in drugs, vessels, vehicles, aircraft, equipment and weapons. With the transfer of the Operation BAT mission Sept. 30, 1985, the wing lost of its UH-1N helicopter force. This left the 1st SOW with HH-53H Pave Low II helicopters, which had superior capabilities to meet special operations taskings.

Today's Marine Corps UH-1N carries an integrated communication and navigation system which includes the Control Display Navigation Units (CDNU), GPS/Doppler navigation, and three multi-channel radios with a satellite communication capability. Mission capabilities are supplemented with an integrated FLIR for night navigation and targeting, a Night Vision Goggle Heads Up Display (NVG HUD), missile defense systems, and the capability to deliver rocket and machine gun fire.

The installation of new communication and navigation equipment in the Marine Corps UH-1N "Huey" helicopters significantly enhances its mission capability and tremendously decreases the pilots' workload. Despite the complexity of this change, this $74 million upgrade was brought to the fleet on schedule and $2 million under budget, due to the combined efforts of the government and industry teams.

Communication and navigation equipment was installed in more than 100 UH-1Ns and into three training simulators. The upgrade includes a state-of-the- art communications and radio package (ARC-210 radio), Doppler Navigation System, control display navigation units with a digital data set, miniature airborne Global Positioning System (GPS) receiver and replacement of the existing TACAN. The Internal Communications System (ICS) on board the helicopter was also replaced with a secure, voice activated system.

The addition of the ARC-210 radio provides secure, digital communications. The satellite communications (SATCOM) system provides secure over-the-horizon communications, allowing the Marine Air/Ground Task Force mission commander to control his forces and coordinate with all other echelons. The number three radio and SATCOM radio systems can now be controlled independently, from the cabin of the aircraft, with the ground commander's communications control station. These next generation radios have reduced the maintenance workload, which in turn increases the mission availability of the aircraft. Installation of the GPS and the Doppler system allows for independent navigation for over-the-horizon and over-water operations.

The ASQ-215 mission data loader allows pilots to use emerging technology to preplan missions, enter waypoints and communications frequencies into a data transfer module. This eliminates the need to enter information by hand, thereby reducing their workload. Now the aircrew has the ability to pre-plan and pre-brief multiple missions, and upon mission tasking, load all required information into the Cockpit Control System (CCS) rapidly and efficiently while preparing for launch, decreasing the response time. The installation of the Collins 800 CCS decreases pilot workload and maintenance troubleshooting time. The CCS allows the pilots to control all the radios and communications systems from one central location.

The highly integrated Built-In-Test (BIT) program enables maintenance crews to run BIT checks on all the installed systems. This check identifies the component causing the system failure to the troubleshooter instantaneously eliminating hours of system troubleshooting. The installation of the improved internal communications system allows secure and encrypted communications between the aircrew and gunners. Now the gunners can talk to the pilots and still use their door-mounted machine guns without taking their hands off the weapons.

This upgrade program was approved in Fiscal Year 1991 with aircraft kit manufacturing beginning later that year at Raytheon Systems Company, formally known as E-Systems, at the Special Operations Forces Support Activity, in Lexington, Ky. Installations began in 1992 and were performed at Naval Air Station Atlanta, Marine Corps Air Station (MCAS) New River, MCAS Camp Pendleton, and MCAS Futenma. The two contractors, DynCorp and Raytheon, with Raytheon providing sole installation support over the past four years, logged more than 195,000 artisan man-hours during the course of this installation program.

A plan was recently put in place to ugrade the UH-1N to the UH-1Y. This will include twin engines, drive trains, a new four-bladed rotor, tail sections, integrated digital cockpits and an upgraded navigation system. The upgrade will extend the life of the model well into the 21st century.

The UH-1Y utility helicopter demonstrated a significant increase in payload, range, speed, and situational awareness over the legacy UH-1N utility aircraft. Assuming internal fuel cell problems can be corrected, the UH-1Y may be able to achieve the required mission radius of 110 nautical miles. The design of the aircraft increases the possibility of tail strikes (mitigated by the redesign of the tail boom stinger), infrared signature, and hover limitations. Excessive noise levels in the UH-1Y cabin degraded mission performance and elevated cabin temperatures might change mission effectiveness in hot weather. Collectively, these problems, if uncorrected, will limit the effectiveness of the UH-1Y across the full range of utility helicopter missions.

Source: http://www.globalsecurity.org/military/systems/aircraft/uh-1n.htm