Douglas A/B-26 Invader
Twin Otter
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Douglas A/B-26 Invader Twin Otter |
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DHC-6 Twin Otter utility aircraft de Havilland Canada May 20, 1965 1966 1965–1988 844 $2,000,000 USD The DHC-6 Twin Otter is a 20-passenger STOL (Short Takeoff
and Landing) utility aircraft developed by de Havilland Canada. The aircraft's fixed tricycle undercarriage,
STOL abilities and high rate of climb have made it a successful cargo, regional passenger airliner and MEDEVAC aircraft. In
addition, the Twin Otter has been popular with commercial skydiving operations. Development of the aircraft began in 1964, with the first flight
on May 20, 1965. A twin-engined replacement for the single-engined Otter had been planned by de Havilland Canada. Twin engines
not only provided improved safety but also allowed for an increase in payload while retaining the renowned STOL qualities.
Design features included double slotted trailing edge flaps and ailerons that work in unison with the flaps to boost STOL
performance. The availability of the 550 shp (410 kW) Pratt and Whitney Canada PT6A-20 propeller turbine engine
in the early 1960s made the concept of a twin more feasible. To bush operators, the enhanced reliability of turboprop power
and the enhanced performance of a twin-engined configuration made it an immediately popular alternative to the single engine,
piston-powered 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, adding a longer nose that was equipped with a larger baggage compartment (except
to aircraft fitted with floats) and fitting a larger door to the rear baggage compartment. All Series 1, 100 and 200 aircraft
and their variants (110, 210) were fitted with the 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 was a 680 hp
(510 kW) engine that was flat-rated to 620 hp (460 kW) for use in the Series 300 Twin Otter. The Series 300
proved to be the most successful variant by far, with 614 Series 300 aircraft and their sub-variants (Series 310 for United
Kingdom operators, Series 320 for Australian operators, etc.) sold before production ended in 1988. After series production ended, the remaining tooling was purchased
by Viking Air of Victoria, British Columbia, which manufacture replacement parts for all of the out of production de Havilland
Canada aircraft. On February 24, 2006 Viking purchased the type certificates from Bombardier Aerospace for all the out of
production de Havilland DHC-1 through DHC-7 aircraft. The ownership of the certificates gives Viking the exclusive right to
manufacture new aircraft. On July 17, 2006, at the Farnborough Air Show, Viking Air announced
its intention to offer a "Series 400" Twin Otter. On April 2, 2007 Viking announced that with 27 orders and options in hand,
it was restarting production of the Twin Otter with a more powerful Pratt & Whitney Canada PT6A-34/35 engine. As of November 2007, 40 firm orders and 10 options have been
taken and a new assembly plant has been established in Calgary, Alberta with customer deliveries commencing summer 2009. Zimex
Aviation of Switzerland will receive the first aircraft. On September 25, 2008, the Series 400 Technology Demonstrator
achieved "power on" status in advance of an official rollout. First flight of the Series 400 technical demonstrator, C-FDHT,
took place October 1, 2008 at Victoria Airport. Two days later, the aircraft departed Victoria for a ferry flight to Orlando,
Florida, site of the 2008 National Business Aviation Association (NBAA) Conference and exhibition. Major changes introduced with the Series 400 include Honeywell
Primus Apex fully integrated avionics, deletion of the AC electrical system, deletion of the beta backup system, modernization
of the electrical and lighting system, and use of composites for non-load-bearing structures such as doors. Twin Otters could be delivered directly from the factory with
floats, skis or tricycle landing gear fittings, making them adaptable bush planes for remote and northern areas including
Canada and the United States, specifically Alaska. 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 the optimum means of travel. Their versatility and
maneuverability have made them popular in areas with difficult flying environments, 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. Widerøe of 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 achieved over 96,000 cycles
(takeoff, flight and landing) per year. Twin Otters are a staple of Antarctic transportation. Four Twin
Otters are employed by the British Antarctic Survey on research and supply flights, and several are employed by the United
States Antarctic Program via contract with Kenn Borek Air. On 24–25 April 2001, two Twin Otters performed the only winter
flight to Amundsen-Scott South Pole Station to perform a medical evacuation. As of August 2006, a total of 584 Twin Otter aircraft (all variants)
remain in service worldwide. Major operators include: Libyan Arab Airlines (16), Maldivian Air Taxi (17), Trans Maldivian
Airways (15), Kenn Borek Air (33) and Scenic Airlines (11). Some 115 airlines operate smaller numbers of the aircraft including
Yeti Airlines in Nepal and in the United Kingdom the FlyBe francise operator Loganair which uses the aircraft to service the
island of Barra in the Hebrides islands. This scheduled service is unique as the aircraft lands on the beach and the schedule
is partly influenced by the tide tables. Ontario's Ministry of Natural Resources is also a long-time operator
of the Otter. Transport Canada still owns three DHC-6 Twin Otters, but they
now see very limited flying time, as their role in Coastal Surveillance has been replaced by a fleet of DHC-8 aircraft. The Twin Otter has been popular with commercial skydiving operations.
It is able to carry up to 22 skydivers to over 13,500 ft (a large load compared to most other aircraft in the industry); presently,
the Twin Otter is used in skydiving operations in many countries. The United States Air Force operates three Twin Otters for
the United States Air Force Academy's skydiving team. General characteristics Performance
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