DHC-6 Twin Otter

DHC-6 Twin Otter

The De Havilland Canada DHC-6 Twin Otter is a two-engine turboprop regional airliner and utility transport, seating up to 19 passengers. One of its specialties is its capability to takeoff and land on short runways. The aircraft was originally produced by De Havilland Canada (now Bombardier) but is currently being built by another Canadian company, Viking Air.

The Twin Otter is an aircraft which can be used in many roles: regional airliner, corporate shuttle, small cargo aircraft, infrastructure support, medical evacuation, paradropping, search and rescue and more. It can operate in the extreme cold of Alaska, Canada and Antarctica, but also in hot deserts. It feels at home in mountainous areas, but can also fly between the islands of an archipelago.

De Havilland Canada began the development of the DHC-6 in 1964 as a twin-engined replacement for the 1950s DHC-3 Otter, a STOL utility aircraft powered by a single piston engine. As power source for the new aircraft DHC chose the 550 shp (410 kW) Pratt & Whitney Canada PT6A-20 turboprop and installed two of them on the wing. The use of turboprop engines quite improved the performance and reliability compared with the DHC-3.

The Twin Otter has a high wing with double-slotted trailing edge flaps and ailerons that work together with the flaps to give it its excellent short takeoff and landing (STOL) characteristics. It can land on grass, gravel, dirt, snow, ice and water. Passengers sit three-abreast (2+1) in an unpressurised cabin. The landing gear is non-retractable.

DHC produced six prototype aircraft designated Series 1. The first production version was the Series 100, of which 109 have been built. In 1968, DHC started production of the improved Series 200 with even better STOL characteristics, a bigger aft cargo door and a longer nose with a larger baggage compartment inside. 115 Srs 200 aircraft were built. All Series 1, 100 and 200 aircraft and their subvariants were fitted with the 550 shaft-horsepower PT6A-20 engines.

Production of the next and most successful version, the Series 300, started in 1969. The Series 300 was fitted with more powerful PTA6-27 engines to improve performance and payload capabilities. De Havilland Canada built 614 Series 300 aircraft until production of the Twin Otter ended in 1988. De Havilland Canada built a total of 844 aircraft.

Twin Otters are ideally suited for operations in thinly populated regions like Alaska and Canada, large parts of Africa and Australia. Several aircraft are employed to support research projects on Antarctica. Twin Otters were and sometimes still are in use with commuter airlines and the regional divisions of major airlines.

Viking Air

Twin Otter tooling was taken over by the Canadian company Viking Air, which started to produce replacement parts for all out-of-production De Havilland Canada aircraft types. In february 2006, Viking also acquired the type certificates from Bombardier Aerospace for all DHC out-of-production aircraft, from DHC-1 through DHC-7 (Dash-7).

This allowed Viking to restart production of the Twin Otter in 2007. Viking developed a much improved version, the Twin Otter Series 400, fitted with more powerful Pratt & Whitney Canada PT6A-34 tuboprops and a modernised cockpit. Composite materials are used in some parts of the airframe.

Viking Air rolled out a Series 400 technology demonstrator on 25 September 2008, which first flew on 1 October 2008 from Victoria Airport. The first really new Twin Otter Series 400 made its maiden flight on 16 February 2010.

The new generation Twin Otter is built at a new plant in Calgary. Production is running at 18 aircraft a year, down from 24 in 2014. The aircraft are delivered with a non-retractable tricycle landing gear (with extra large tyres if necessary), straight floats, amphibious floats, skis or wheel-skis.

The Guardian 400 is a patrol aircraft for military and government purposes (Photo: Viking Air). It can be fitted with a nose-mounted electro-optical sensor turret, a belly-mounted 360 degrees search radar and/or a searchlight on one of up to four pylons.

In total, over 900 Twin Otters have been built, including more than 100 by Viking Air. Around 500 of 'legacy' Twin Otter aircraft are still in service.

DHC-6 Series 300 Twin Otter Specifications

Wingspan: 19.8 m (65 ft 0 in). Length: 15.77 m (51 ft 9 in). Height: 5.90 m (19 ft 4 in).
Empty weight: 3,363 kg (7,415 lb). Max. take-off weight: 5,670kg (12,500 lb).
Accommodation: 19 passengers. Range: 1,434 km (775 nm). Cruise speed: 278 km/h (150 kts).
Engines: two Pratt & Whitney Canada PT6A-27 turboprops (507 kW - 680 shp).

Twin Otter Srs 400 Specifications

Wingspan: 19.8 m (65 ft 0 in). Length: 15.77 m (51 ft 9 in). Height: 5.94 m (19 ft 6 in).
Empty weight: 3,121 kg (6,881 lb). Max. take-off weight: 5,670kg (12,500 lb).
Accommodation: 19 passengers. Range: 1,480 km (799 nm). Cruise speed: 278 km/h (150 kts).
Engines: two Pratt & Whitney Canada PT6A-34 turboprops (560 kW - 750 shp).