Twin Otter development continues

 - February 27, 2008, 9:10 AM

Viking Air’s relaunch of the fabled Twin Otter is progressing on schedule, and the first modified airplane incorporating all the planned new features of the production airplane should fly in the fourth quarter. Delivery of the first newly manufactured and recertified Twin Otter to Swiss customer Zimex Aviation is planned for next year’s first quarter.

Viking Air has been manufacturing parts for and supporting the Twin Otter and other de Havilland airplanes for more than 15 years, including manufacturing new wings for the Twin Otter. In February 2006, Viking purchased the type certificates for the DHC-6 Twin Otter and DHC-1 (Chipmunk) through -7 (Dash 7) from Bombardier.
At first, according to Viking president and CEO David Curtis, the company’s focus was on supporting the more than 600 remaining Twin Otters of the 844 that were built until production ceased in 1988. He said that before Viking got the type certificates, people asked Bombardier why it did not return the airplane to production.

Planning for Volume Production
Viking hired consulting firm Conklin & de Decker to study the market for all of the DHC airplanes and ascertain which, if any, might spark marketplace interest large enough to justify reopening a production line. The results, by a large margin, showed that Twin Otter buyers needed 400 airplanes in 10 years–a market “we can look at more seriously,” Curtis and his team concluded.

Viking didn’t jump into manufacturing right away; instead it talked to potential customers to see if they would place firm orders in numbers high enough to make production worthwhile. Viking needed orders for at least 20 airplanes, Curtis said, “to make a go of it.” But buyers ordered twice as many, and now the backlog stands at more than 50 Twin Otters and the next available delivery slot is in 2012. None of those orders are from U.S. operators, according to Curtis. “The aircraft is well known in those [parts of the world] where there’s lack of infrastructure.”

Viking is first modifying a technology demonstrator -300 series Twin Otter, the last model built, with all of the 120 modifications that will be incorporated in the new -400 version. Major changes will include a modern avionics suite and composite doors. Performance figures will remain the same because making changes to them would entail much more certification work, but the new Twin Otter will have a lower empty weight.

Other improvements include a new engine, Pratt & Whitney Canada’s PT6A-34, which is more powerful than the original PT6A-27, but the -34 will be flat-rated to match the -27s takeoff power for better hot-and-high performance. Viking plans to offer PT6A-35 engines and four-blade propellers as an option.

The fuselage is the largest part of the airframe that Viking needs to manufacture. Unfortunately, Boeing, which used to own the de Havilland product line before it sold that division to Bombardier, scrapped the fuselage and other major component jigs for the Twin Otter. The wing jigs and tooling for detail parts were retained, and Viking has used those in its Twin Otter support program.

Viking is using computer design tools to convert all the Twin Otter drawings to digital format, which is then used to produce tooling for the new parts that need to be built. An additional benefit, said Curtis, is that tolerances are now so much better than they were 20 to 30 years ago that “we’re getting a way tighter project. We’re already seeing that the aircraft is going to go together with much more precision than was ever envisioned back in the 1970s and 1980s, when the thing was being built.”

In Canada–unlike the U.S.–Viking doesn’t need to obtain a separate production certificate for volume production. “Because we own the type certificate, the company already has the approval to manufacture the aeronautical product,” Curtis said.
In addition to first customer Zimex, other companies that have signed up for new Twin Otters include Trans Maldivian Airways, Air Seychelles, Air Moorea and leasing company Loch Ard Otters.

While there is a need for new Twin Otters, Curtis said, “The economics of developing a new airplane for that market don’t line up. So we take a platform like the Twin Otter and apply what we know today to an already great design; our non-recurring investment is significant, but it’s not like developing a new product.” The cost of putting the Twin Otter back into production, including the improvements, is about 25 percent of the cost of developing a new airplane, he said.

Viking is building a new facility at its Victoria, British Columbia headquarters to prepare for Twin Otter production.