Bombardier / DHC Dash 7
Bombardier / DHC Dash 7
The De Havilland Canada Dash 7 (officially designated 'DHC-7') is a four-engine turboprop regional airliner, seating up to 50 passengers. Its specialty is its capability to operate to and from airports with short runways.
De Havilland Canada developed the Dash 7 in the early 1970s. DHC was well-known as a designer and builder of STOL-aircraft (STOL = Short Take Off and Landing). The idea behind the Dash 7 was an aircraft with the same 50-seat capacity as the Fokker F27 and Hawker Siddeley HS748, but with much better STOL-capabilities to serve airports which were inaccessible for its competitors. DHC had in mind small airports in city centres and outlying airports with unpaved runways.
The Dash 7 performed its maiden flight on 27 March 1975. Certification followed in May 1977 and Rocky Mountain Airways was the first airline to start flying with the type on 3 February 1978.
The Dash 7 indeed has impressive STOL-characteristics, achieved by an advanced high-mounted wing fitted with double slotted trailing edge flaps over the entire span which much increase the wing area at takeoff. Extra lift is generated by the airflow from the propellers over the wing, which features spoilers to help shorten the landing distance. The aircraft has a T-tail to keep the elevator clear of the propeller slipstream during takeoff. The landing gear folds forward into the inner engine nacelles. The pressurised fuselage has a circular cross section and offers four-abreast seating (2+2).
For operations to city centre airports, the Dash 7 had to become a good - silent - neighbour. To achieve this De Havilland Canada installed oversized propellers which turn at lower speeds than usual in order to prevent the tips nearing the speed of sound, when propellers usually become noisy.
De Havilland Canada developed only a small number of versions. The basic passenger aircraft is the Dash 7 Series 100. The Srs. 101 is a passenger/freighter variant and the Srs. 103 a Combi. An improved main version is the Series 150, with an higher takeoff weight and more fuel capacity to increase range. The Series 151 was a freighter variant.
The Dash 7 was not a commercial success. The aircraft was often flying to large airports where its unique STOL-capabilities weren't necessary. At some airports the runways were lengthened to enable other aircraft types to land there too. An example is London City Airport, which was designed with the Dash 7 as the only aircraft to operate from there in mind, but later the runway was lengthened and today the BAe 146, the Embraer E-Jets and even the Airbus A318 operate from this airport. Operators also faced high maintenance costs because the Dash 7 with its four Pratt & Whitney PT6A engines required more maintenance than twin-engine aircraft.
Production ended in 1988, after Boeing took over De Havilland Canada. In 1992 the US aerospace giant sold the company to Bombardier. The type certificate for the Dash 7 design went to Viking Air, a Canadian aircraft manufacturer which restarted production of another De Havilland Canada aircraft type, the DHC-6 Twin Otter.
De Havilland Canada built 113 Dash 7s, including a number of aircraft delivered to military forces. In 2018 around ten aircraft are still in airline service.
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DHC Dash 7 Specifications
Wingspan: 28-35 m (93 ft 0 in). Length: 24.58 m (80 ft 8 in). Height: 7.98 m (26 ft 2 in).
Empty weight: 12,560 kg (27,690 lb). Max. take-off weight: 20.000 kg (44,000 lb).
Accommodation: 50 passengers. Range: 1,279 km (690 nm). Cruise speed 400 km/h (215 kts).
Engines: four Pratt & Whitney Canada PT6A-50 turboprops (835kW - 1220 shp).