David Eyre 
Photo © Viking Air
25 November 2011: Perth-based aviation company AVWest is about to take delivery of its new Viking Air DHC-6 Twin Otter 400, VH-ZZH (construction number 851, test reg C-FUVA). The aircraft was ordered on 15 April 2010 and will be delivered fitted with amphibious floats. It was added to the Australian aircraft register on 17 November 2011.
The DHC-6 Twin Otter was originally designed and built by De Havilland Canada as a larger, twin-engined replacement for the 11-seat De Havilland DHC-3 Otter. The Otter was powered by a single Pratt & Whitney R-1340 radial piston engine, and two engines were preferred for increased safety and performance.
Development of the Twin Otter started in 1964, using two Pratt and Whitney Canada PT6A-20 turboprop engines of 550shp (410kW). The prototype DHC-6 Twin Otter first flew on 20 May 1965, and was immediately popular with bush operators due to its excellent STOL performance, reliability and solid construction. The Twin Otter carries 19 passengers and can land on an airstrip only 366 metres long. The Twin Otter was sold to operators all over the world, operating in all kinds of extreme conditions.
During the 1980s, the Canadian government decided to sell De Havilland Canada, and in 1986, DHC was sold to Boeing. Boeing allegedly used this purchase in an attempt to win an Air Canada airliner order. Boeing guaranteed the Canadian Government that it would not cease production of any DHC products, but within two years had ceased production of the DHC-6 Twin Otter and the DHC-7 Dash 7. Only the DHC-8 Dash 8 continued in production. Production of the De Havilland DHC-6-300 Twin Otter Series 300 ended in 1988, even though the aircraft was still successful, after the 844th aircraft was delivered. When the Air Canada order went to Airbus in 1988, Boeing immediately decided to sell De Havilland Canada, and the company was sold to Bombardier in 1992.
Viking Air, based at Victoria, British Columbia, Canada had been refurbishing Twin Otters for over 36 years. In 2005, Viking Air purchased from Bombardier the production tooling for the DHC-1 Chipmunk, DHC-2 Beaver, DHC-3 Otter, DHC-4 Caribou, DHC-5 Buffalo, DHC-6 Twin Otter, and DHC-7 Dash 7. All of these types were no longer in production. On February 24, 2006 Viking purchased the type certificates for all of these types – this gave them the rights to build new aircraft.
Whilst Viking could have designed a new aircraft, it would have cost three times as much as modernising the Twin Otter. After refining the design to use more powerful Pratt & Whitney Canada PT6A-34 (or -35 engines), and modern avionics, on 2 April 2007, Viking announced that it had obtained 27 orders and options, and was restarting production of the Twin Otter.
Viking converted a DHC-6-300 to be the Twin Otter 400 Technology Demonstrator, and this made its first flight on 1 October 2008 at Victoria International Airport. On 16 February 2010, the first new production Twin Otter Series 400 (cn 845) made its first flight – this was delivered to Zimex Aviation of Switzerland .
The Twin Otter is still popular with its operators – around 600 of the 844 built are still in service, and the second-hand Twin Otters are still worth almost as much as a new production aircraft ($4.5 million). The new Twin Otter 400 is also popular, with orders for 55 aircraft received by September 2011, and a production backlog through to 2016. Viking has built 10 new aircraft, and delivered 7, and is increasing production rate to an initial 18 aircraft per year, and later to 24 per year.
