 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "De Havilland Canada Dash 7" – news ·newspapers ·books ·scholar ·JSTOR(July 2018) (Learn how and when to remove this message) |
| Dash 7 | |
|---|---|
 Brymon Airways Dash 7 in 1983 | |
| General information | |
| Type | STOLregional airliner |
| National origin | Canada |
| Manufacturer | de Havilland Canada |
| Status | In limited service |
| Primary users | Various airlines |
| Number built | 114 |
| History | |
| Manufactured | 1975–1988 |
| Introduction date | February 3, 1978 |
| First flight | March 27, 1975 |
| Developed into | De Havilland Canada Dash 8 |
Thede Havilland Canada DHC-7, popularly known as theDash 7, is aturboprop-powered regionalairliner withshort take-off and landing (STOL) performance. Variants were built with 50–54 seats. It first flew in 1975 and remained in production until 1988 when the parent company,de Havilland Canada, was purchased byBoeing in 1986 and later sold toBombardier. In 2006 Bombardier sold thetype certificate for the aircraft design toViking Air, which was later reorganized asDe Havilland Canada.
In the 1960s, de Havilland Canada was already well known worldwide for their series of high-performance STOL aircraft, notably the very popularDHC-2 Beaver andDHC-6 Twin Otter. However, these aircraft were generally fairly small and served outlying routes, as opposed to the busierregional airliner routes which were already well served by larger, higher-performance turboprop aircraft such as theFokker F27,Fairchild F-27,Convair 580,Convair 600 andHawker Siddeley 748.
The de Havilland Canada company personnel felt they could compete with these designs in a roundabout way. With their excellent STOL performance, their designs could fly into smaller airports located in city centres and smaller, outlying, more austere airports having runways that the other aircraft could not easily use (unpaved, unimproved). The original specification called for an aircraft that could carry 40 passengers and operating from runways only 2,000 ft long (610 m),[1] and designed for, with a full load of passengers, the ability to fly 700 nautical miles (1296km),[1] or a range of 805 statute miles.[Note 1]
With new noise restrictions coming into effect throughout the 1970s,[1] an aircraft tailored for this role would also have to be very quiet. Propeller noise is a factor of blade length and chord and the speed at which it rotates. To meet these new regulations, the new design used much larger (oversized) propellers geared to rotate at a lower speed than is normally designed. Much of the problem sound from a typical propeller is generated at the tips of the blades which are rotating at or just beneath the speed of sound. By using oversize propeller blades, there is no need to have the blade tip reaching near the speed of sound, and the rotating speed can therefore be reduced without sacrificing thrust. In reducing the speed, this noise is reduced substantially. The Dash 7 often landed at only 900 rpm, and took off at only 1,210 rpm.
In other respects, the new DHC-7 was essentially a larger, four-engine version of the Twin Otter: the general layout remained similar, with a highaspect ratio, high-mounted wing, and similar details of the cockpit and nose profile. Changes included the addition of cabin pressurization (requiring a switch to a fuselage with a circular cross-section), landing gear that folded forward into the inner engine nacelles, and a large T-tail intended to keep the elevator clear of the propwash during take-off (the Twin Otter'sempennage was acruciform arrangement).
The Twin Otter incorporated "flaperons" that drooped the ailerons as part of the flaps, but these were not included in the Dash 7 due to weight and complexity. Instead, the ailerons were reduced in size to allow more flap area, and were augmented with two sets of roll spoilers, orspoilerons. The inboard roll spoilers operate at all speeds. while the outboard roll spoilers only operate at speeds less than 130 KIAS to allow for more roll control at slower speeds. Upon touchdown, both the inboard and outboard roll spoilers extend in unison to aid in destroying lift created by the wing. Each wing also includes two ground spoilers which only extend on touchdown. Most of the trailing edge is spanned by a complex, doubleFowler flap arrangement for high lift at low speed. During a typical STOL landing, flaps are selected to the 45° position, generating more lift and drag, thus allowing for steeper descents and lower approach speeds. Depending on weight, the VREF speed with flaps at 45° is between 70 and 85 knots. On touchdown, through "squat switches" in the main gear, the flaps automatically retract to the 25° position, thus reducing lift once on the runway and producing better braking performance. The flaps also retract to 25° when engine power is increased during ago-around procedure. The four-engine layout aids lift at low speeds due to the wide span of the propellers blowing air over the wing ("propwash"). Whenreverse thrust is selected on landing, the props reverse pitch, push air forward, and slow the aircraft very effectively along with the antiskid main wheel brakes. More importantly, if an engine fails, the asymmetric thrust is much less than on a twin-engine layout, thereby increasing safety and allowing for a lower minimum control speed with an engine inoperative.
Development started in 1972 and the prototype first flew on March 27, 1975. Testing went smoothly, and the first delivery took place toRocky Mountain Airways on February 3, 1978. The Dash 7 enabled Rocky Mountain Airways to operate scheduled passenger air service from Denver into the AvonSTOLport in Colorado which was controlled by the airline. The Avon STOLport was located in a mountain valley in close proximity to theVail, CO ski resort. Another close-in ski resort airfield served by Rocky Mountain Airways with Dash 7 flights from Denver wasSteamboat Springs Airport in Colorado. With a relatively short runway length of 4,452 feet and an airfield elevation of 6,882 feet, the Dash 7 was well suited for operations from this airport located in the Rocky Mountains. Flying asContinental Express via acode sharing agreement withContinental Airlines, Rocky Mountain Airways also operated the Dash 7 into theTelluride Airport located in theSan Juan Mountains of southwest Colorado with this mountain airport having an airfield elevation of 9,078 feet thus making it one of the highest airports in the U.S.[3]
Kapalua Airport on the island ofMaui,Hawaii was built byHawaiian Airlines with a 3000-foot runway, specifically for Dash 7 operations. Scheduled passenger flights with new Dash 7 turboprops began on March 1, 1987. In 1993, this private airport was acquired by the state of Hawaii.
One hundred Dash 7 turboprops were delivered by 1984, when the production line was put on hold in favour of theDash 8. Another 13 were delivered between 1984 and 1988, when the production lines were removed when Boeing bought the company. The last Dash 7 was bought byTyrolean Airways.[4]
The original Series 100 represents the vast majority of the aircraft delivered, and came in two models; the DHC-7-102 passenger version and -103combi with an enlarged cargo door. These were followed by the Series 110 which met British CAA requirements, including the -110 and -111, and finally the Series 150 which included additional fuel capacity and an improved interior in the -150 and -151. Plans were made for a Series 200 with the new PT6A-50/7 engines which improved hot-and-high power, but these plans were shelved when Boeing ended production of the design.
The mixture of features on the Dash 7 met with limited commercial success. Most commuter airline turboprop operators used the aircraft as feeder liners into large airports, where the STOL performance was not considered important. In comparison to other feeder liners, the Dash 7's four engines required twice the maintenance of a twin-engine model, thereby driving up operational costs. Finally, those airports that did require a high-performance STOL operation were generally small and well served by the Twin Otters; had an airport needed a larger plane to serve its customer base, they would have built a longer runway. One exception to this was operations atLondon City Airport, which upon opening in 1987, was capable of handling few other aircraft types besides the Dash 7 due to its relatively short runway and steep approach. The runway at London City was subsequently lengthened, and the approach angle reduced somewhat and since accepts airliners such as theAirbus A220,Airbus A318,British Aerospace BAe 146 andEmbraer 190 types. Noise criteria remain strict in comparison with other international airports.
The Dash 7 also gained a number of military orders. The first of these was for two aircraft for theCanadian Armed Forces, which needed them to transport high-ranking passengers and freight around Europe. These aircraft received the CF designation CC-132 and were delivered to412 Transport Squadron atCanadian Forces Base Lahr, inWest Germany.[5]
TheUnited States Army operates several Dash 7 aircraft as surveillance platforms with the designation EO-5C (RC-7B before 2004)[6] under the Airborne Reconnaissance Low program.
Transport Canada operates a single DHC-7-150IR aircraft to conduct maritime surveillance, pollution monitoring, and ice patrols as part of the Transport Canada National Aerial Surveillance Program. The aircraft's home base isOttawa. During the summer, this aircraft conducts patrols throughout the Canadian Arctic, Alaska, and Greenland. During the fall and winter, this aircraft conducts patrols of the Great Lakes and east or west coasts of Canada as required.
The design of a much more conventional twin-engine design commenced at de Havilland in 1978, resulting in the extremely popularDash 8. The DHC-7 production line eventually delivered 114, of which six have been lost and one scrapped. Many of the rest remain in service.[7][8]
The American bandWilco released a song called "Dash 7" on their 1995 albumA.M.[citation needed]
The de Havilland Canada DHC-7 has been involved in six accidents (and 10 incidents overall) with a total of 68 fatalities.[7]
As of September 2024, a total of 19 Dash 7 aircraft (all variants) remain in service.[19]
TheBritish Antarctic Survey operates a single Dash 7 in support of its research programme inAntarctica. The aircraft undertakes regular shuttle flights between eitherStanley on theFalkland Islands, orPunta Arenas, Chile, and theRothera Research Station onAdelaide Island. It also operates to and from the ice runway at theSky Blu conducting coastal pollution and ice patrols across the Canadian Arctic.
Data from Jane's All The World's Aircraft 1982–83[23]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
Related lists
