MD Helicopters MD 500

MD 500
	An MD 500E
Role	Light utility helicopter
National origin	United States
Manufacturer	Hughes Helicopters; McDonnell Douglas Helicopter Systems; MD Helicopters
First flight	27 February 1963
Introduction	1967
Status	In service
Primary user	Various police agencies; Korean People's Air Force
Produced	1967–present
Number built	4,700
Developed from	Hughes OH-6 Cayuse
Variants	McDonnell Douglas MD 500 Defender; Boeing AH-6
Developed into	MD Helicopters MD 600

The MD Helicopters MD 500 series is an American family of light utility civilian and military helicopters. The MD 500 was developed from the Hughes 500, a civilian version of the US Army's OH-6A Cayuse/Loach. The series currently includes the MD 500E, MD 520N, and MD 530F.

Design and development[]

A Hughes 500 Model 369HS

A Hughes 500 Model 369D

The successful Hughes 500/MD 500 series began life in response to a U.S. Army requirement for a Light Observation Helicopter (LOH).^[3] Hughes' Model 369 won the contest against competition from Bell and Hiller. The subsequent OH-6 Cayuse first flew in February 1963.

The 500 series design features shock-absorbing landing skid struts, a turboshaft engine mounted at a 45-degree angle toward the rear of the cabin pod, a fuel tank cell under the floor and the battery in the nose. The engine exhaust port is located at the end of the cabin pod underneath the tailboom. It has a short-diameter main rotor system and a short tail, giving it agile control response and is less susceptible to weather-cocking.

Hughes won the U.S. Army's LOH contest with its OH-6 helicopter by submitting a very low and aggressive price per airframe (without an engine). Due to rising prices, the U.S. Army later re-opened the contest, where Hughes offered the machine at a more realistic price, but was undercut by the redesigned Bell OH-58 Kiowa (military JetRanger). OH-6 helicopters were still ordered by the U.S. Army, though at a much reduced number.

Hughes/MD 500[]

Prior to the OH-6's first flight, Hughes announced it was developing a civilian version, to be marketed as the Hughes 500, available in basic five- and seven-seat configurations.^[3] A utility version with a more powerful engine was offered as the 500U (later called the 500C).

The improved Hughes 500D became the primary model in 1976, with a more powerful engine, a T-tail, and a new five-blade main rotor; a four-blade tail rotor was optional.^[3] The 500D was replaced by the 500E from 1982 with a pointed nose and various interior improvements, such as greater head- and legroom. The 530F was a more powerful version of the 500E optimized for hot and high work.

McDonnell Douglas acquired Hughes Helicopters in January 1984, and from August 1985 the 500E and 530F were built as the MD 500E and MD 530F Lifter.^[3] Following the 1997 Boeing-McDonnell Douglas merger, Boeing sold the former MD civil helicopter lines to MD Helicopters in early 1999. Military variants are marketed under the MD 500 Defender name.

MD 520N[]

A NOTAR MD 520N

The MD 520N introduced a revolutionary advance in helicopter design, dispensing with a conventional anti-torque tail rotor in favor of the Hughes/McDonnell-Douglas-developed NOTAR system.^[3] Exhaust from a fan is directed through slots in the tailboom, using the Coandă effect to counteract the torque of the main rotor, and a controllable thruster at the end of the tailboom is used for yaw control. Because the fan is enclosed in the tailboom, tail rotor noise—the major source of noise from most conventional helicopters—was significantly reduced. It also eliminated the vulnerable exposed tail rotor blades, eliminating the possibility of persons being injured or killed on the ground and the cause for many confined area maneuvering accidents.

McDonnell Douglas originally intended to develop the standard MD 520N alongside the more powerful hot-and-high optimized MD 530N; both were launched in January 1989 and were based on the conventional MD 500E. The MD 530N was the first to fly, on December 29, 1989, and the MD 520N first flew on May 1, 1990. Development of the MD 530N was suspended when McDonnell Douglas decided that the MD 520N met most customer requirements for the 530N. Certification for the MD 520N was awarded on September 13, 1991, and the first was delivered on December 31 that year.

In 2000, MD Helicopters announced enhancements to the MD 520N, including an improved Rolls-Royce 250-C20R+ engine with 3% to 5% more power for better performance on warm days, and changes to the diffuser and fan rigging, also increased range.

Operational history[]

El Salvador[]

During the Salvadoran Civil War, the Salvadoran Air Force operated six MD 500Ds, which were supplemented later by nine MD 500Es supplied by the United States in 1983. These were used as gunships, armed with 7.62 mm Miniguns and unguided rockets, as well as being used for reconnaissance and liaison duties. One MD 500D and two MD 500Es were lost to SA-7 missiles in 1989 and 1990. By the end of the conflict, only one MD 500D and six MD 500Es were in operational condition.^[4]

North Korea[]

In 1985, North Korea managed to circumvent US export-control barriers by covertly purchasing 87 civilian-type Hughes MD 500s from a West German export firm, before the US government learned of the illegal action by North Korea and moved to stop further deliveries to the country. There are reports indicating that at least sixty of the helicopters delivered to North Korea were modified to serve as helicopter-gunships. As South Korea produces the MD 500 domestically (under license) for use by its own armed forces, the modified helicopters operated by North Korea were deemed useful in conducting covert or deceptive operations against South Korea (such as incursions past the border).^[5]

The modified MD 500 helicopters were finally revealed by North Korea and seen by the US and European countries during North Korea's Victory Parade held on 27 July 2013 in Pyongyang, to commemorate the 60th anniversary of the end of the Korean War in 1953. Images and analyses done regarding North Korea's MD 500 helicopters show that they have been modified significantly to serve as light attack helicopters, such as modification work on the helicopters for them to be mounted with Soviet-designed AT-3 Sagger anti-tank wire-guided missiles.^[6]

Variants[]

369: Military prototype designated YOH-6A.
369A: Military production designated OH-6.
MD 500C (369H): Improved five-seat commercial variant powered by an Allison 250-C18B rated at 317 shp (236 kW); certified in 1966.
Kawasaki-Hughes 369HS: Built under license by Kawasaki Heavy Industries in Japan alongside OH-6J.
MD 500M Defender (369HM): Military export version as the MD 500 Defender; certified in 1968.
MD 500C (369HS): Improved four-seat commercial variant by an Allison 250-C20 rated at 400 shp (298 kW); certified in 1969.
MD 500C (369HE): A 369HS with higher standard interior fittings, Certified in 1969.
MD 500D (369D): New commercial version from 1976 powered by an Allison 250-C20B rated at 420 shp (313 kW); certified in 1976.
MD 500E (369E): Executive version of the 500D with recontoured nose; certified in 1982.
NH-500E: Italian-built version of the 500E. License-produced by before merging with Agusta.^[2]
MD 500N: NOTAR (NO TAil Rotor) version of the 500E, certified in 1991. Powered by Rolls Royce (formerly Allison) 250-C20R/2 rated at 450 shp.
MD 530F (369F): Hot and high version of the 500E powered by a Rolls Royce (formerly Allison) 250-C30HU rated at 650 shp (485 kW), certified in 1984.

Unmanned Little Bird Demonstrator and AH-6: A civilian 530F modified by Boeing Rotorcraft Systems to develop UAV technologies for both civilian and military applications.^[7]

Military[]

For military variants, see McDonnell Douglas MD 500 Defender and Hughes OH-6 Cayuse.

Operators[]

Kern County Sheriff's MD 500E

The MD 500 is widely operated by private individuals, companies and law enforcement agencies around the world.

Belgium

Federal Police^[8]

Colombia

National Police of Colombia^[9]

Costa Rica

Air Vigilance Service^[10]

Ecuador

National Police of Ecuador^[11]

Finland

Utti Jaeger Regiment^[12]

Honduras

Honduran Air Force^[13]

Hungary

Hungarian Police^[14]

Indonesia

Pelita Air
Indonesian Air Force - 12 ex-Pelita Air Hughes 500C were given to the Air Force in 1982. Retired from service.^[15]^[16]

Italy

State Forestry Corps^[17]

Kenya

Kenya Air Force

North Korea

Korean People's Air Force^[18] - Total 87 were smuggled to North Korea.

United States

Academi^[19]
Columbus Division of Police^[20]
Fresno County Sheriff's Department^[21]
Glendale Police Department^[22]
Hawaii County Fire Department^[23]
Houston Police Department^[24]
Kansas City Police Department^[25]
Las Vegas Metropolitan Police Department^[26]
Pasadena Police Department^[27]
Prince George's County Police Department^[28]
Riverside Police Department^[29]
San Diego County Sheriff's Department^[30]
St. Louis Metropolitan Police Department^[31]
St. Louis County Police Department^[32]

Specifications (MD 530F)[]

Data from MD500E PERFORMANCE SPECIFICATIONS,^[33] The International Directory of Civil Aircraft^[3]

General characteristics

Crew: 2
Capacity: 3 passengers
Length: 32 ft 7 in (9.93 m)
Height: 8 ft 9 in (2.67 m)
Empty weight: 1,591 lb (722 kg)
Max takeoff weight: 3,550 lb (1,610 kg)
Powerplant: 1 × Allison 250-C30 turboshaft engine, 650 shp (480 kW)
Main rotor diameter: 27 ft 4 in (8.33 m)
Main rotor area: 587.5 sq ft (54.58 m²)
Blade section: - NACA 0012^[34]

Performance

Maximum speed: 152 kn (175 mph, 282 km/h)
Cruise speed: 135 kn (155 mph, 250 km/h)
Range: 232 nmi (267 mi, 430 km)
Service ceiling: 18,700 ft (5,700 m)
Rate of climb: 2,070 ft/min (10.5 m/s)

Specifications (MD 500C)[]

Data from ^[35]