OH-6 Cayuse

The Hughes Helicopters OH-6 Cayuse (nicknamed Loach) is a single-engine light helicopter with a four-bladed main rotor used for personnel transport, escort and attack missions, and observation. Hughes also developed the Model 369 as a civilian helicopter, the Hughes Model 500, currently produced by MD Helicopters.


In 1960, the United States Army issued Technical Specification 153 for a Light Observation Helicopter (LOH) capable of fulfilling various roles: personnel transport, escort and attack missions, casualty evacuation and observation. Twelve companies took part in the competition and Hughes Tool Company's Aircraft Division submitted the Model 369. Two designs, those submitted by Fairchild-Hiller and Bell, were selected as finalists by the Army-Navy design competition board, but the U.S. Army later included the helicopter from Hughes as well.

The first Model 369 prototype flew on February 27, 1963. Originally designated as the YHO-6A according to the Army's designation system, the aircraft was redesignated as the YOH-6A in 1962 when the Department of Defense created a Joint designation system for all aircraft. Five prototypes were built, fitted with a 252 shp Allison T63-A-5A, and delivered to the U.S. Army at Fort Rucker, Alabama to compete against the other 10 prototype aircraft submitted by Bell and Fairchild-Hiller. During the course of the competition, the Bell submission, the YOH-4, was eliminated as being underpowered (it used the 250shp T63-A-5). The bidding for the LOH contract came down to Fairchild-Hiller and Hughes. Hughes won the bid, and the Army awarded a contract for production in May 1965, with an initial order for 714 which was later increased to 1300 with an option on another 114. Production reached 70 helicopters in the first month.

Japanese OH-6

In Japan, 387 OH-6s were produced under licence by Kawasaki Heavy Industries and used by the Japanese Ground Self-Defense Force (JGSDF), Japanese Maritime Self-Defense Force (JMSDF), the Japanese Coast Guard, and civilian operators. Beginning in 2001, the OH-6s of the JGSDF are in the process of being replaced by Kawasaki's new observation helicopter, the Kawasaki OH-1.

Operational history

Shortly after production began, the OH-6 began to demonstrate what kind of an impact it would have on the world of helicopters. The OH-6 set 23 world records for helicopters in 1966 for speed, endurance and time to climb. On March 23, 1966, Jack Schwiebold set the closed circuit distance record in a YOH-6A at Edwards Air Force Base, California. He flew without landing for 1,739.96 mi (2,800.20 km). And on April 7, 1966, Robert Ferry set the long distance world record for helicopters. He flew from Culver City, California to Ormond Beach, Florida, covering a total of 1,923.08 nm (2,213.04 mi, 3,561.55 km).

Production OH-6A craft entered service in 1966, arriving in the Vietnam War thereafter. The pilots dubbed the little helicopter Loach, a word created by pronunciation of the acronym of the program that spawned the aircraft, LOH (light observation helicopter). The helicopter quickly became noted for high performance and low noise due its four-bladed rotor and small size. The OH-6A would act as a scout to spot enemy positions, while only lightly armed with a fixed minigun. The most common configuration had an observer/gunner either in the left seat or in the rear seat. Most commonly, the Loach worked in conjunction with another OH-6 or an AH-1 Cobra gunship. A pair of OH-6s was sometimes known as a "white team", while an element of AH-1 Cobras was referred to as a "red team". An OH-6 and an AH-1 operating together comprised a "Pink team".

"The Quiet One"

A heavily-modified pair of OH-6As were utilized by the CIA via Air America for a covert wire-tapping mission in 1972. The aircraft, dubbed 500P (penetrator) by Hughes, began as an ARPA project, codenamed "Mainstreet", in 1968. Development included test and training flights in Culver City, California and at Area 51 in 1971. In order to reduce their acoustic signature, the helicopters (N351X and N352X) received a four-blade 'scissors' style tail rotor (later incorporated into the Hughes-designed AH-64 Apache), a fifth rotor blade and reshaped rotor tips, a modified exhaust system and various performance-boosts. Deployed to a secret base in southern Laos (PS-44) in June 1972, one of the helicopters was heavily damaged during a training mission late in the summer. The remaining helicopter deployed a wiretap near Vinh, Vietnam on the night of 5 December-6, 1972, which provided the United States with useful information during the Linebacker II campaign and Paris Peace Talks. Shortly thereafter, the aircraft were returned to the U.S., dismantled and quietly found new homes for the now-standard 500s.

160th Special Operations Aviation Regiment

Following the April 1980 failure of Operation Eagle Claw, it was determined that the military lacked aircraft and crews who were trained and prepared to perform special operations missions. To remedy this shortcoming, the Army began developing a special aviation task force to prepare for the next attempt to rescue the hostages; Operation Honey Badger.

Task Force 160th

The architects of the task force identified the need for a small helicopter to land in the most restrictive locations and that was also easily transported on Air Force transport aircraft. They chose the OH-6A scout helicopter to fill that role, and it became known as the Little Bird compared to the other aircraft in the task force, the UH-60A and the CH-47C. As a separate part of the project, armed OH-6As were being developed at Fort Rucker, Alabama.

The pilots selected to fly the OH-6A helicopters came from the 229th Attack Helicopter Battalion and were sent to the Mississippi Army National Guard's Army Aviation Support Facility (AASF) at Gulfport, Mississippi, for two weeks of qualification training in the aircraft. When the training was completed, C-141 aircraft transported the aircraft and crews to Fort Huachuca, Arizona, for two weeks of mission training. The mission training consisted of loading onto C-130 transport aircraft which would then transport them to forward staging areas over routes as long as 1000 nautical miles. The armed OH-6 aircraft from Fort Rucker joined the training program in the fall of 1980.

Operation Honey Badger was canceled after the hostages were released on 20 January 1981, and for a short while, it looked as if the task force would be disbanded and the personnel returned to their former units. But the Army decided that it would be more prudent to keep the unit in order to be prepared for future contingencies. The task force, which had been designated as Task Force 158, was soon formed into the 160th Aviation Battalion. The OH-6A helicopters used for transporting personnel became the MH-6 aircraft of the Light Assault Company and the armed OH-6As became the AH-6 aircraft of the Light Attack Company.


Prototype version.OH-6A
Light observation helicopter, powered by a 263-kW (317-shp) Allison T63-A5A turboshaft engine.OH-6A NOTAR
Experimental version.OH-6B
Re-engined version, powered by a 298-kW (420-shp) Allison T63-A-720 turboshaft engine.OH-6C
Proposed version, powered by a 313.32-kW (400-shp) Allison 25-C20 turboshaft engine, fitted five rotor blades.OH-6J
Light observation helicopter for the JGSDF. Built by Kawasaki Heavy Industries under licence in Japan. Based on the OH-6A Cayuse helicopter.OH-6D
Light observation, scout helicopter for the JGSDF. Built by Kawasaki Heavy Industries under licence in Japan. Based on the Hughes Model 500D helicopter.EH-6B
Special Forces electronic warfare, command post version.MH-6B
Special Forces version.TH-6B
A Navy derivative of the MD-369H, six McDonnell Douglas TH-6B Conversion-in-Lieu-of-Procurement aircraft are used as an integral part of the United States Naval Test Pilot School's test pilot training syllabus. The aircraft and associated instrumentation and avionics are used for the in-flight instruction and demonstration of flying qualities, performance and missions systems flight test techniques.AH-6C
Modified OH-6A to carry weapons and operate as a light attack aircraft for the 160th SOAR(A).MH-6C
Special Forces version.

For other AH-6 and MH-6 variants, see MH-6 Little Bird.




See also

External links

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