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Beaver revival

British Columbia-based Advanced Wing Technologies (AWT) has unveiled a new wing for the de Havilland DHC-2 Beaver which enables a 340kg payload increase and improves speed, range and short-take-off-and-landing performance.

The new wing dramatically benefits the Beaver today, but it is the long-term potential which is causing as much excitement among operators and conversion specialists alike. The wing, dubbed the AW 6000, is expected to be the catalyst for a large range of upgrades covering everything from wide-scale re-engineing with turbine or modern reciprocating powerplants to a fuselage stretch.

The wing was demonstrated for the first time to operators at the de Havilland Beaver 50th anniversary convention and trade show in Victoria, British Columbia and it is emerging at an important time for the Beaver. After successive years of a shrinking fleet, the number of aircraft in operation stabilised in the early 1990s and has since continued to grow, with more aircraft in service now than in 1987, and even scrapped and abandoned airframes in great demand. Prices have skyrocketed from around $40,000 in the late 1980s to more than $300,000 today.

Nasa technology

The AW 6000 incorporates a variety of NASA aerofoil technologies, and has been under development since 1985 when two US-based companies, Aeronautical Technical Services and Flight Structures International, began study work under contract to Modern Wing of Canada. The design studies were based on a concept developed by aerospace engineers Bill Foyle and John Hill. After initial design work was completed, the project "-sort of sat in limbo", until revived with new capital in 1995, says AWT vice-president, Tony Rogers. Flight-testing began on a demonstrator in 1996, and the landplane version received Transport Canada certification in July 1997. "We're pursuing certification with the FAA [US Federal Aviation Administration]on wheels before we can get our certification for the float-equipped version," he adds.

AWT is hoping for FAA certification "by the end of the year". Four wingsets are in production. The company is setting up the AW 6000 line at a new 2,300m2 (24,000ft2) manufacturing site in Richmond, British Columbia, where it plans to move in November from Vancouver Airport. Production will be set at between four and six shipsets a month, depending on demand, says Rogers. Overall, AWT expects a demand for around 200 shipsets over the next five years.

Combined with EDO 4930 floats, the wing enables the Beaver's gross weight to be increased by almost 450kg, to 2,700kg. AWT estimates that the rewinging, priced at a minimum of C$110,000 ($80,000), depending on customer choice, will quickly pay for itself. Based on sorties of 1-3h and an average utilisation of 500h a year, the company estimates that the new wing has the potential to increase revenue by between $24,000 and $120,000 a year.

The aft-loaded wing has a 17% thickness ratio compared to the standard wing's 16%. The effect of the slightly deeper section, plus the change to a "wet" wing fuel-tank system and a 1.2m span increase, is a huge leap in capacity from 360litres to 590litres, resulting in a 70% range increase. The main aerodynamic improvements include an improved Fowler flap, a leading-edge cuff to counter the abrupt flow separation found over the original outboard wing section, and flow energisers at the wing root to generate vortices at high angles of attack. Other changes include a large strake in front of the horizontal tail and stall strips.

Companies attracted to using the new wing include Cambell River-based Sealand Aviation, which is studying a 1m stretch of the Beaver achieved by inserting an extension in the fuselage aft of the trailing edge.

Turbine conversions

The potential of the AW 6000 has also attracted companies offering turbine conversions for the Beaver, among them Vazar Aerospace of Bellingham, Washington. The company is in the middle of certifying 23 variants of the Pratt & Whitney Canada PT6A turboprop covering the 370-560kW (500-750shp) range for installation on the Beaver in addition to holding a certificate for an Allison C250-B17F retrofit.

Flying with the new wing also improves safety, says AWT representative pilot Dave Crerar, who demonstrated the rewinged aircraft to Flight International. A downwind take-off from Victoria harbour was achieved at just 44kt (80km/h) and subsequent rate of climb with 10í flap, 2,000rpm and 760mm of boost was a spritely 650ft/m (3.3m/s).

Some previously dangerous characteristics have been eliminated, such as the Beaver's tendency to roll inverted if stalled in landing configuration with full flap and full go-around power applied. Another manoeuvre, dubbed the "oh my God, there's a moose!" turn, has also been rendered safe. Entering the turn at 100kt, the pilot pulls 3g as the aircraft begins a 60í bank right turn. "Normally, a Beaver would stall, flip into a spin and you die," says Crerar, who recovers the aircraft before making a landing with a full stop after just 120m (400ft).

With recovered and rebuilt DHC-2s being added to the fleet, and improvements such as the AW 6000, it seems likely that many Beavers are heading towards their 100th anniversary.

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