de Havilland Canada attempted to market the Buffalo for civil use as the "Transporter", but the demonstration aircraft crashed at the 1984 Farnborough Airshow and the project was abandoned. DHC-6 Twin Otter One of Canada's most successful commercial aircraft designs with more than 800 built, the Twin Otter remains popular for its rugged construction and STOL capabilities. Development dates back to January 1964, when DHC commenced work on a twin turboprop variant of the DHC-3 Otter as a STOL commuter airliner and utility transport. The wings were lengthened, the rear fuselage, tail, and nose were redesigned, and seating capacity was increased to 18. Design features included double-slotted trailing-edge flaps and flaperons (ailerons that act in unison with the flaps) to boost STOL performance. The type's first flight on 20 May 1965. After receiving certification in mid-1966, the first Twin Otter variant, the Series 100, entered service with the Ontario Department of Lands and Forests. The Series 200, introduced in April 1968, had an extended nose and reconfigured rear cabin storage compartment, greatly increasing cargo space. The Series 300, introduced in 1969, had more powerful engines, allowing a 450-kg (1,000-lb) increase in takeoff weight and a 20-seat interior. All models can be fitted with skis or floats. DHC production ceased in late 1988, but in 2010, Viking Air restarted Twin Otter production with the introduction of the Series 400. Production was suspended during the COVID-19 pandemic; in July 2022, the company announced that it was reviewing the programme and supply chain, with a decision on when to resume production expected "in the near future". DHC-7 Dash 7 The four-engined DHC-7, popularly known as the Dash 7, was designed as a STOL 50-seat regional airliner capable of operating from strips as short as in length. It was meant to serve small city airports, where noise abatement requirements were particularly strict, and featured four slow-turning propellers to cut noise. To enhance its STOL performance, the Dash 7 employs many aerodynamic devices, such as double-slotted wing flaps that span about 75% of the trailing edge of the wing and four spoilers per wing; on landing, the flaps partially retract and the spoilers fully deploy to maximize braking. Financial backing from the Canadian government allowed the launch of the DHC-7 program in the early 1970s, resulting in the maiden flight on 27 March 1975. The type was certificated on 2 May 1977 and entered service