Country of origin:

Canada

Description:

Light utility transport and third-level airliner

Power Plant:

Two 432 kw (579 eshp) Pratt & Whitney PT6A-20 turboprops

Specifications:

History:

Using basically the same fuselage and wing as the single-engine DHC-3 Otter, the de Havilland DHC-6 Twin Otter was designed with a new nose and tail assembly, the cabin section being extended in length to seat up to 20 passengers. STOL performance was achieved using double-slotted full-span trailing-edge flaps, the outer sections of which also operated differentially as ailerons.

Development began in January 1964, construction of the prototype beginning in November that year. Certification was received in 1966 and the first aircraft was delivered to the Ontario Department of Lands in Canada.

The manufacturer described the Twin Otter as seating up to 19 passengers and providing competitive operation over stage lengths of up to 1,127 km (700 miles). Its ability to perform from short semi-prepared runways permitted service to be provided to localities where air connection had not previously been practical. Much engineering effort was devoted towards keeping the Twin Otter structurally uncomplicated, operationally versatile, and economically practical.

The prototype CF-DHC-X made its first flight at Downsview near Toronto in Ontario on 20 May 1965. Aimed basically at the third-level commuter market, the Twin Otter was sold to many operators around the world, and was operated extensively on floats and skis, particularly on tourist flights in Canada and the Maldives. Turboprop power was chosen in the form of the then-new Pratt & Whitney PT6A developed in Canada by United Aircraft of Canada Ltd.

The first three aircraft were powered by PT6A-6 engines, but the initial production series had the PT6A-20 engine. After 115 aircraft of the Series 100 had been delivered, production changed to the Series 200 in April 1968. This variant had a slightly lengthened nose with a larger baggage capacity. Production of this variant also totalled 115 machines.

The Twin Otter had a flight-crew of two and, in the standard regional airline role, it had seating for 19 passengers. It could also be configured to operate in the executive transport role and as a freighter, aerial ambulance or survey aircraft. Examples were obtained by the US Army with which it became known as the UV-18A.

The Twin Otter has been very popular in Australasia with more than 30 examples being registered over the years. Operators have included Ansett/MAL and Trans Australia Airlines (TAA – later Australian Airlines) in New Guinea prior to that country’s independence, TAA in northern Queensland and East West Airlines for a period. Probably the operator which used the type for the longest period of time was Aero Pelican, based at Belmont, NSW, on the Sydney – Belmont commuter service. This company finally concluded its services with the Twin Otter in 2005, the Belmont airstrip closing and services from Sydney to Newcastle resuming from Williamtown, the Twin Otters being replaced by Jetstreams. Aero Pelican initially operated two, and later three, Series 200 aircraft for some years. In 1981 they were replaced by Series 300 aircraft.

Other operators included Skywest in Western Australia, Qantas subsidiary Sunstate in Queensland, Transtate Airlines, Sunshine Express, Eastland Air, Flightwest, Regional Pacific Air, MacRobertson Miller Airlines, Australian Regional Airlines, Trans West Airlines, etc.

In Australia the Australian Army at Oakey, QLD leased DHC-6 Twin Otters in 1997 for a period and they saw service with No 173 Squadron, which eventually received three, two of these aircraft becoming VH-HPT (c/n 707 – ex VH-USW, VH-SFJ [ntu], 4R-UAA) and VH-HPY (c/n 706 – ex VH-FNZ, P2-RDV, YJ-RVI, F-ODGB). This machine VH-HPY was leased in 1997 but crashed at Bismark Range near Simba, PNG on 28 November 1997 and was not rebuilt. The third aircraft was VH-OHP (c/n 527 – ex VH-VNY, P2-RDM, RP-C-1312, P2-RDM, N9SP, N379WW, C-GDHA) which later became TI-AZV in Costa Rica.

One Twin Otter VH-BMG (c/n 214) was operated for a period from February 1970 by the Australian Bureau of Mineral Resources.

In New Guinea a number of operators used the type, including Talair and Goroka Air. Hevi-Lift leased a Twin Otter in 1999 before obtaining one of its own. Other operators included Milne Bay Air, Airlink of Rabaul, Island Aviation of Rabaul, Southwest Air of Mendi, and Missionary Aviation Fellowship. When Ansett Airlines of Papua New Guinea operated in that region it had a small fleet of Twin Otter Series 300s, and Trans Australia Airlines had a fleet of about 14, most of these being taken over by Territory Airlines after the airline withdrew from New Guinea.

In 1995 a Twin Otter on delivery to Great Barrier Airlines of Auckland ditched near Hawaii and was lost. Operators of the Twin Otter in New Zealand have included Mt Cook Airlines and Coast Air.