Workhorse turboprops

Sales continue to outpace those of jets, based on strong economics, large cabins and flexible mission profiles.

Quest Kodiak

Quest Aircraft manufactures the Kodiak—a 6 to 8-pax single-engine turboprop utility aircraft. The Sandpoint ID-based company hopes the rugged aluminum structure combined with superior STOL performance and high useful payload will benefit utility operators worldwide.

Powered by a PT6A-34 rated at 750 shp, the Kodiak has a full fuel load capability of 1085 lbs and can takeoff in less than 1000 ft. A Garmin G1000 integrated avionics suite with SVS is standard equipment. New interior options—the Tundra and Timberline—were an­nounced in 2011.

Available in 2013, these interiors feature Kydex panels with composite materials contributing to a further weight reduction that will increase the Kodiak's useful load.

Kodiak is available as either an amphibian or land-based aircraft. Large fleet operators include Mis­sion Aviation Fellowship and the US Fish and Wildlife Service, which operates a fleet of 10 Kodiak amphibians.

Pacific Aerospace 750XL

New Zealand-based Pacific Aero­space produces the PAC 750XL—a utility aircraft with extreme STOL (XSTOL) capabilities. The PAC 750XL is used around the world to carry large payloads in rugged conditions. Many aircraft are used to support non-government organizations such as the UN World Food Program.

The 750XL can take off in 800 ft while lifting a 4000-lb payload. As with the Kodiak, the reliable PT6A-34 powers this 8-pax utility aircraft. A large cargo pod is rated to carry up to 1000 lbs of additional cargo.

Viking Twin Otter 400

After Bombardier's purchase of de Havilland Canada (DHC) in 1998, Viking Aircraft purchased the rights to legacy DHC aircraft, including the Beaver, Otter and Twin Otter.

In 2007, Viking made the decision to relaunch production of the DHC6 Twin Otter—an aircraft with a 40-year history and the most successful 19-seat aircraft ever built. Viking embarked on a complete makeover of the Twin Otter by incorporating more than 800 design changes to improve the aircraft's safety and value.

A flightdeck update replaced analog instruments with Honeywell's Primus Apex system, which includes large LCD screens for the PFDs and MFD. Rebranded as the Series 400, the Twin Otter now has a fully updated electrical system, multiple composite structures to reduce weight and upgraded PT6A-34 engines.

Like other utility turboprops featured, the Twin Otter can operate on land or water. Viking certified the Series 400 in 2010 and has exported it to operators around the globe.

Emerging designs

Evektor EV55 Outback

Czech GA manufacturer Evektor launched the EV55 to compete with the Caravan and replace older piston twins such as the Cessna 400 and PA31 series. The prototype EV55 Outback first flew in Jun 2011 and is engaged in a busy certification program.

In Mar 2012, the Kunovice-based OEM selected the CMC SmartDeck integrated avionics package for the 9-pax aircraft. Developed originally by L3, SmartDeck is slated to fly on EV55 s/n 003—the first production conforming aircraft—in 2013.

Powered by 2 PT6A-21 engines (536 shp), the unpressurized EV55 will be able to cruise at 220 kts at 10,000 ft.

As the name implies, the Outback has STOL performance and can operate from unimproved 2000-ft strips. Evektor hopes to certify the EV55 by 2015. In Oct 2012, AeroGeo, a Russian geophysical exploration company, signed an MOU for 29 Outbacks in a deal valued at $61 million.

Kestrel K350

Kestrel K350 is a 6-seat all-composite aircraft based on the former Farnborough F1 proof-of-concept aircraft originally designed by Richard Noble, a speed fanatic. Having resurrected the program, the Kestrel is now slated to be Alan Klapmeier's next big project, following the highly successful Cirrus SR20/22.

On Klapmeier's arrival at Kestrel, he went to work refining the design of the aircraft and moving the company headquarters from Bruns­wick ME to Superior WI—with the help of a $30-million tax incentive.

Target cruise speeds will top the charts of all single-engine turboprops at 325 kts. The 1000-shp Honeywell TPE331-14GR has replaced the original PT6A, and a full airframe parachute system is a likely addition. According to Klap­meier, the aerodynamics are now frozen and further system selection, including avionics, is ongoing.

Defining workhorses

"Workhorse" is an overused cliché—one that is used all too often to describe turboprop aircraft. All corporate aircraft have to earn their keep one way or another, as business tools that ultimately increase a company's productivity and value.

Claims of turboprops' superior runway performance over that of jets are also often inaccurate. With the exception of the utility aircraft that offer true STOL capabilities, most turboprops have runway performance on par with and sometimes worse than the straight-wing Cessna Citations or the Embraer Phenom 100/300.

Given that aircraft design involves compromises, each flight department has to evaluate which aircraft is the best fit for its operation.

Beyond these analytical comparisons, there are a number of intangibles such as product support to consider when selecting an aircraft. Turboprops are unique in offering superior economics on shorter flights. As a byproduct, they are also relatively environmentally friendly. This could be considered turboprops' sweet spot.

Stuart Lau is a consultant. He leads the IHST HFDM Working Group and acts as an IHST liaison to the Global HFDM Steering Group. He is also a pilot for a large international airline and a safety and accident investigation committee member. Lau has been associated with Pro Pilot since 1996.


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