De Havilland Canada DHC-6 Twin Otter

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DHC-6 Twin Otter
A West Coast Air Twin Otter floatplane.
Type	utility aircraft
Manufacturer	de Havilland Canada
Maiden flight	20 May 1965
Produced	1965-1988
Number built	844

The DHC-6 Twin Otter is a 20-passenger STOL feederliner and utility aircraft developed by de Havilland Canada. It is often called the most successful aircraft program in Canada's history. The aircraft's fixed tricycle undercarriage, STOL abilities and relatively high rate of climb have made it a successful cargo, regional passenger airliner and MEDEVAC aircraft. In additon, the Twin Otter has been popular with commercial skydiving operations. It is generally limited to carrying 22 jumpers (a relatively large load compared to most other aircraft in the industry); presently, the Twin Otter is used in skydiving operations in Sweden, Australia, USA and Norway and other nations worldwide.

Contents 1 Design and development 2 In use 3 Today 4 Military Operators 5 Specifications (300 series) 5.1 General characteristics 5.2 Performance 6 References 7 Related content

[edit] Design and development

Development of the aircraft began in 1964, with the first flight on 20 May 1965. A twin-engined replacement for the Otter had been planned by de Havilland Canada. Twin engines not only provided safety but also allowed for an increase in payload. While retaining the renowed STOL qualities, the availability of the 500 shp Pratt and Whitney propeller turbine from United Aircraft of Canada in the late '50s made the concept of a twin more feasible. To bush operators, the enhanced reliability and performance of twin engines made it an immediately popular alternative to the single-engined Otter which had been flying since 1951.

The first six aircraft produced were designated Series 1, indicating that they were prototype aircraft. The initial production run consisted of Series 100 aircraft, serial number seven to 115 inclusive. In 1968, Series 200 production began with serial number 116. Changes made at the beginning of Series 200 production included improving the STOL performance as well as adding a longer nose that was equipped with a larger baggage compartment (except to aircraft fitted with floats) and a fitting a larger door to the rear baggage compartment. All Series 1, 100, and 200 aircraft and their variants (110, 210) were fitted with 550 shaft horsepower PT6A-20 engines.

In 1969, the 300 series was introduced, beginning with serial number 231. Both aircraft performance and payload were improved by fitting more powerful PT6A-27 engines. This would prove the most successful variant by far, with 614 Series 300 aircraft and their variants (Series 310, 320, etc.) sold before production ended in 1988.

[edit] In use

Twin Otters could be delivered with floats, skis or tricycle landing gear direct from the factory becoming popular bush planes in Alaska and northern Canada. Many Twin Otters still serve in the far north, but they can also be found in Africa, Australia, Antarctica and other regions where bush planes are preferred. Their versatility and maneuverability have made them popular in areas with difficult flying conditions, including Papua New Guinea. In Norway, the Twin Otter paved the way for the network of short-field airports, connecting the rural areas with the larger towns with outstanding reliability, and remained in service until 2000 on certain routes. Norway was, at one time, the world's largest operator of Twin Otters. During one period of its tenure in Norway, the Twin Otter fleet produced over 96,000 cycles (takeoff, flight and landing) per year.

[edit] Today

After series production ended, the remaining tooling was purchased by Viking Air of Victoria which manufactures replacement parts for most of the early de Havilland line. On 24 February 2006, Viking purchased the type certificates from Bombardier Aerospace for all the original de Havilland DHC 2- DHC 7 designs^[1]. The ownership of the certificates gives Viking the exclusive right to manufacture new aircraft.

On 17 July 2006, at the Farnborough Air Show, Viking announced ^[2]its intention to offer a "Series 400" Twin Otter. Restarting the production would be dependent on the ability to realize enough inital orders.

As of August 2006, a total of 349 Twin Otter aircraft (all variants) remain in air carrier service worldwide. Major operators include: Libyan Arab Airlines (16), Maldivian Air Taxi (17), Trans Maldivian Airways (12), Kenn Borek Air (17) and Scenic Airlines (11). Some 115 airlines operate smaller numbers of the aircraft. ^[3]

[edit] Military Operators

• Argentina (Air Force, Army, Navy), Afghanistan, Australia, Benin, Canada, Chile, Colombia, Ecuador, Ethiopia, France (Air Force, Army), Haiti, Jamaica, Nepal, Norway, Panama, Paraguay, Peru, Sudan, Uganda, United States (US Air Force, US Army)

The only Twin Otters operated by the United States Air Force are stationed at the USAF Academy in Colorado Springs, CO. They are used by the Academy Parachute Team, the Wings of Blue, for year-round parachuting operations.

[edit] Specifications (300 series)

[edit] General characteristics

• Crew: Minimum 1, commonly operated with 2 crew.
• Capacity: 13 passengers (common configuration for Series 100), 19 or 20 passengers (common configuration for Series 200 and 300 models)
• Length: 51 ft 9 in( 15.77 m)
• Wingspan: 65 ft (19.8 m)
• Height: 19 ft 6 in 5.9 m)
• Wing area: 420 ft² (39 m²)
• Empty: between 7,000 lb (3,363 kg) and 8,000 lb (3,628 kg)
• Loaded:
• Maximum takeoff: cargo configuration

Series 100 and 200: 11,579 lb (5,252 kg). Series 300: 12,500 lb (5,670 kg)

• Powerplant:

Series 100 and 200: 2 x PT6A-21 turboprops, 550 hp (410 kW). Series 300: 2 x PT6A-27 turboprops, flat-rated to 620 hp (460 kW) from 680 hp (507 kW)

• US Military Designation: UV-18 / V-18

[edit] Performance

• Maximum speed: 183 knots (338 km/h)
• Ferry Range: 920 nautical miles (1,705 km)
• Service ceiling: 26,700 ft (8,140 m)
• Rate of climb: 1600 ft/min (8.1 m/s)
• Wing loading: kg/m² ( lb/ft²)
• Power/mass: hp/lb ( kW/kg)

[edit] References

• Hotson, Fred W. The de Havilland Canada Story. Toronto: CANAV Books, 1983. ISBN 0-07-549483-3.
• Rossiter, Sean. Otter & Twin Otter: The Universal Airplanes. Vancouver: Douglas & McIntyre, 1998. ISBN 1-55054-637-6.

[edit] Related content

Wikimedia Commons has media related to: DHC-6 Twin Otter

Related development

• de Havilland Canada DHC-3 Otter

Comparable aircraft

• Antonov An-2
• Antonov An-28
• Britten-Norman Islander
• Fairchild Dornier 228
• GAF Nomad
• Harbin Y-12
• IAI Arava
• LET L-410
• Shorts SC.7 Skyvan

Designation sequence

DHC-3 - DHC-4 - DHC-5 - DHC-6 - DHC-7 - DHC-8

 

See also