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OH-6 Cayuse
OH-6A Cayuse helicopter on lift off
Role Light Observation Helicopter / Utility
Manufacturer Hughes Tool Co. - Aircraft Division
First flight 27 February 1963
Introduction 1966
Status Active service
Primary user United States Army
Produced 1965–present
Number built 1420 (OH-6A)[1]
Unit cost
US$19,860 (1966)[2][note 1]
Variants MD Helicopters MH-6 Little Bird
MD Helicopters MD 500
McDonnell Douglas MD 500 Defender

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


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.

OH-6 helicopter in flight

The first Model 369 prototype flew on 27 February 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 (188 kW) Allison T63-A-5A,[3] 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 250 shp (190 kW) T63-A-5). The bidding for the LOH contract came down to Fairchild-Hiller and Hughes. Hughes won the bid,[4] and the Army awarded a contract for production in May 1965, with an initial order for 714 that was later increased to 1,300 with an option on another 114. Hughes's price was $19,700 per airframe, less engine, while Hiller's price was $27,000 per airframe, less engine. It should be noted that the Hiller design had a boosted control system, while the Hughes design did not. This would account for some of the price difference. Hughes is reported to have told Jack Real that he lost over $100 million in building 1,370 airframes.[5][6] It is reported that Hughes had directed his company to submit a bid at a price below the actual production cost of the helicopter in order to secure this order, resulting in substantial losses on the U.S. Army deal, with the anticipation that an extended production cycle would eventually prove financially viable.[7][8]

In 1968 Hughes submitted a bid to build a further 2,700 airframes. Stanley Hiller complained to the U.S. Army that Hughes had used unethical procedures; therefore, the Army opened the contract for rebidding by all parties. Hiller did not participate in the rebidding, but Bell did, with their redesigned Model 206. After a competitive fly-off, the Army asked for sealed bids. Hughes bid $56,550 per airframe, while Bell bid $54,200. Reportedly, Hughes had consulted at the last moment with his confidant Jack Real, who recommended a bid of $53,550. Hughes, without telling him, added $3,000 to the bid and thus lost the contract.[5][6]

Japanese OH-6

In Japan, 387 OH-6s were produced under license 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.[9] On 23 March 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). Subsequently, on 7 April 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).[10]

In 1964 the U.S. Department of Defense issued a memorandum directing that all U.S. Army fixed-wing aircraft be transferred to the U.S. Air Force, while the U.S. Army transitioned to rotor-wing aircraft. The U.S. Army's fixed wing airplane, the O-1 Bird Dog, which was utilized for artillery observation and reconnaissance, would be replaced by the OH-6A helicopter.[11] The aircraft entered service in 1966, arriving in the Vietnam War thereafter. The pilots dubbed the new helicopter Loach, a word created by pronunciation of the acronym of the program that spawned the aircraft, LOH (light observation helicopter).

"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 5–6 December 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 as the now-standard 500s.[12]

160th Special Operations Aviation Regiment

Following the April 1980 failure of Operation Eagle Claw (the attempted rescue of American hostages in Tehran), 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 160

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 MH-60 and the MH-47. As a separate part of the project, armed OH-6As were being developed at Fort Rucker, Alabama.[13]

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 1,000 nautical miles (1,900 km). The armed OH-6 aircraft from Fort Rucker joined the training program in the fall of 1980.[14]

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.

On 1 October 1986, to help meet the increasing demands for support, the 1-245th Aviation Battalion from the Oklahoma National Guard, which had 25 AH-6 and 23 UH-1 helicopters, was placed under the operational control of the 160th. The 1-245th AVN BN enlisted 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. The following 2 week mission was to Yuma for night operation training. The AH/MH little birds were lifted by, 1 C-5, 2 C-130 along with all support kits for the Battalion. Crews trained side by side with the 160th for all operational concepts. The 1-245 modified infantry night vision goggles and worked to develop the necessary skills for rapid deployment with little birds and C-130's.[15]


A TH-6B Cayuse helicopter takes off for a training flight from NAS Patuxent River, Maryland

Prototype version.
Light observation helicopter, powered by a 263 kW (317 shp) Allison T63-A5A turboshaft engine.
Experimental version.
Re-engined version, powered by a 298 kW (420 shp) Allison T63-A-720 turboshaft engine.
Proposed version, powered by a 313.32 kW (400 shp) Allison 25-C20 turboshaft engine, fitted five rotor blades.
Light observation helicopter based on the OH-6A Cayuse for the JGSDF. Built by Kawasaki Heavy Industries under license in Japan.
Light observation, scout helicopter based on the Hughes Model 500D for the JGSDF. Built by Kawasaki Heavy Industries under license in Japan.[16]
Special Operations electronic warfare, command post version.
Special Operations version.
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.[17]
Modified OH-6A to carry weapons and operate as a light attack aircraft for the 160th SOAR(A).
Special Operations version.

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


Military and government operators

Japanese OH-6D of the JGSDF

United States

Former operators

A Danish OH-6 Cayuse helicopter lifts off from a landing zone

 Dominican Republic
Flag of Denmark.svg Denmark
 Republic of China (Taiwan)
United States


General characteristics

  • Crew: 2
  • Length: 30 ft 10 in - 32 ft 2 in (9.4 m - 9.8 m)
  • Rotor diameter: 27 ft. 4 in (8.33 m)
  • Height: 8 ft 6 in - 11 ft 2 in (2.6 m - 3.4 m)
  • Empty weight: 1,975 lbs (896 kg)
  • Max. takeoff weight: 3,549 lbs (1,610 kg)
  • Powerplant: 1 × One Allison T63-A-5A or T63-A-700 turboshaft, 317 hp (236 kW)


  • Maximum speed: 152 knots (175 mph, 282 km/h)
  • Cruise speed: 135 knots (155 mph, 250 km/h)
  • Range: 232 nm (430 km (267 mi))
  • Service ceiling: 15,994 ft (4,875 m)
  • Rate of climb: 2,067 ft/min (10.5 m/s)


See also


  1. Holley and Sloniker state that Hughes underbid the competition to buy into the contract.
  1. Francillon 1990, p. 248.
  2. Holley and Sloniker 1997, p. 8.
  3. "Type Certification Data Sheet NO. H3WE". U.S. Department of Transportation Federal Aviation Administration. 10 May 2002.$FILE/H3WE.pdf. Retrieved 28 January 2012. 
  4. "Centennial of Flight Commission". Hughes Aircraft. 2003. Retrieved 28 January 2012. 
  5. 5.0 5.1 Cefaratt 2002, p. 77.
  6. 6.0 6.1 Real, Jack. "The Real Story." Vertiflite, Fall/Winter 1999, pp. 36–39.
  7. Real, Jack G.; Yenne, Bill (2003). The Asylum of Howard Hughes. Xlibris. ISBN 978-1-4134-0876-8. 
  8. Day, Dwayna Q. (28 January 2008). "Monster chopper". The Space Review. Retrieved 20 April 2012. 
  9. "History of Rotorcraft World Records, List of records established by the 'YOH-6A'."[dead link] Fédération Aéronautique Internationale (FAI). Retrieved: 11 January 2011.
  10. "Rotorcraft World Records, Absolute Rotorcraft World Records."[dead link] Fédération Aéronautique Internationale (FAI). Retrieved: 11 January 2011.
  11. Adcock 1998, p. 32.
  12. Chiles, James R. (February–March 2008). "Air America's Black Helicopter". Air & Space Smithsonian. pp. 62–70. ISSN 0886-2257. Retrieved 20 April 2012. 
  13. Durant and Hartov 2006, pp. 48–49.
  14. Durant and Hartov 2006, p. 56.
  15. Durant and Hartov 2006, p. 57.
  16. "Jane's Aircraft Upgrades, MD Helicopters (Hughes) Model 500 (Military Versions)". 24 November 2011. Retrieved 29 April 2013. 
  17. "U.S. Navy Fact Sheet TH-6B helicopter". United States Navy. 20 February 2009. Retrieved 28 January 2012. 
  18. "World Air Forces 2013". Flightglobal Insight. 2013. Retrieved 28 February 2013. 
  19. "Arma Aerea de la Armada Espanola". Retrieved 26-February-2013. 
  20. "Atlanta Police return to the air". Retrieved 28-February-2013. 
  21. "Chilton County Sheriff acquires OH-6". Retrieved 28-February-2013. 
  22. "N911GB". Retrieved 28-February-2013. 
  23. "Gainesville Police OH-6A". Demand media. Retrieved 28-February-2013. 
  24. "Dominican Republic Air Force Unit History". Retrieved 26-February-2013. 
  25. "Hughes OH-6A Cayuse DRAF". Retrieved 26-February-2013. 
  26. "Flyvevåbnet 369 HM". Retrieved 26-February-2013. 
  27. "日本のヘリコプター半世紀(1960年代)". Retrieved 28-February-2013. 
  28. "japanese maritime self defence force OH-6J". Retrieved 28-February-2013. 
  29. "JSDMF OH-6J". Demand media. Retrieved 28-February-2013. 
  30. "Historical Aircraft". Retrieved 26-February-2013. 
  31. "The last of an old warrior". Retrieved 28-February-2013. 
  32. "CBP retires the "Loach" after 32 years". Retrieved 26-February-2013. 
  33. "US Navy TH-6B Cayuse". Retrieved 26-February-2013. 
  • Adcock, Al (1988). O-1 Bird Dog In Action - Aircraft No. 87. Squadron Signal Publications number 87. ISBN 978-0-89747-206-7. 
  • Cefaratt, Gil (2002). Lockheed: The People Behind the Story. Turner Publishing Company. ISBN 978-1-56311-847-0. 
  • Durant, Michael J.; Hartov, Steven; Durant, Michael (2007). The Night Stalkers. Penguin Group. ISBN 978-0-399-15392-1. 
  • Francillon, René J. (1998). McDonnell Douglas Aircraft Since 1920. Naval Institute Press. ISBN 978-0-87021-428-8. 
  • Holley, Charles; Sloniker, Mike (1997). Primer of the Helicopter War. Nissi Publishing. ISBN 978-0-944372-11-1. 

External links

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