De Havilland Canada DHC-6 Twin Otter

Summary

Category	Transport aircraft
Origin country	🇨🇦 Canada
First flight	20 May 1965
Year of introduction	1966
Number produced	985 units
Average unit price	$7 million

Description

Development of the aircraft began in 1964 as a twin-engine replacement for the single-engine DHC-3 Otter, designed to retain the DHC-3's STOL capabilities. A key design feature included double-slotted trailing-edge flaps and ailerons that worked in unison with the flaps to enhance STOL performance. The availability of the 550 shaft horsepower (410 kW) Pratt & Whitney Canada PT6A-20 turboprop in the early 1960s made the concept of a twin feasible. The first flight took place on 20 May 1965. From 1965 to 1988, De Havilland Canada built the aircraft, ceasing production after 844 had been produced. Viking Air purchased the type certificate and restarted production in 2008, before re-adopting the DHC name in 2022. In 2023, DHC restarted production of the Series 300, in addition to the Series 400 produced by Viking.

The initial Series 100 aircraft were powered by two 550 shp PT6A-20 engines. The Series 200 incorporated enhancements based on initial operational experience, including improvements to STOL performance, a longer nose with a larger baggage compartment, and a larger door to the rear baggage compartment. The Series 300 introduced more powerful Pratt & Whitney Canada PT6A-27 engines, flat rated to 620 hp, which improved aircraft performance and payload. The Series 400 incorporated Honeywell Primus Apex fully integrated avionics, modernized electrical and lighting systems, composite materials for non-load-bearing structures, and Pratt & Whitney Canada PT6A-34 engines.

Operational capabilities include factory delivery with floats, skis, or tricycle landing gear. The aircraft is used in remote and northern regions, including Canada and Alaska, and areas with challenging flying environments such as Papua New Guinea. It facilitated a network of short-field airports in Norway and was used by commuter airlines in the United States for scheduled passenger operations, including those utilizing dedicated STOLports, and also provided connecting feeder service for larger carriers. Furthermore, the Twin Otter is utilized in Antarctic transportation by programs such as the British Antarctic Survey and the United States Antarctic Program for research and supply flights.

Main Variants:

DHC-6 Series 100: Initial production version powered by two 550 shp Pratt & Whitney PT6A-20 engines.
DHC-6 Series 200: Improved version of the Series 100 with enhancements including a longer nose and larger baggage door.
DHC-6 Series 300: Featured Pratt & Whitney Canada PT6A-27 engines, flat rated to 620 hp, improving performance and payload.
Viking Air DHC-6 Series 400: New production version first delivered in 2010, with Pratt & Whitney Canada PT6A-34 engines and modernized avionics.
DHC-6 Classic 300-G: Updated DHC-6 Series 400 featuring a glass cockpit.

Technical specifications

Version: DHC-6-300
Maximum speed	315 km/h (196 mph)
Wing area	39 m² (419.8 sqft)
Wingspan	20 m (65.6 ft)
Height	6.0 m (19.6 ft)
Length	15.8 m (51.9 ft)
Service ceiling	7620 m (25000 ft)
Empty weight	3175 kg (7000 lbs)
Max. takeoff weight	5670 kg (12500 lbs)
Climb rate	8.1 m/s (26.6 ft/s)
Powerplant	2 × turboprops Pratt & Whitney Canada PT6A-27 delivering 410 kW