The case for twin- versus single-turboprop light transport aircraft is being forcefully argued by Vulcanair, which is relaunching its Viator aircraft here at the Dubai airshow. Convinced that the total fuel burn of two Rolls-Royce 250 B17C engines flat-rated at 328 shp is comparable to that of a larger single turbine in the 600-shp range, the Italian manufacturer believes that performance and safety will tip the scales in its favor.

Vulcanair has inherited a number of highly respected aircraft designs from previous owners, although some have not yet sold in significant numbers. Consequently, the elegant designs of Stelio Frati are often widely admired but rarely produced in quantity.

An exception is the P68 twin piston-engine aircraft, which has continued in production, albeit intermittently since 1978. However, the twin-turboprop-powered AP68TP 600 Viator derivative has fared less well, a fact that Vulcanair plans to change.

The company has spent the last two years studying the market for utility aircraft and has concluded that avgas is becoming increasingly difficult to source as well as becoming expensive. At the same time it contends, the new breed of higher-powered multifuel piston engines have neither proved their reliability, nor become widely available.

Although there is a widespread perception that all twin-engine aircraft are more expensive to operate than single-engine aircraft, customer inquiries suggest that there is still an unsatisfied demand. Hence the decision to relaunch the Viator and start accepting orders here at the show.

Like the basic P68 model, the Viator is of all-metal unpressurized construction but unlike the earlier design, it has a retractable undercarriage, which helps toward the maximum speed of 220 knots. The extended fuselage can accommodate nine passengers and two pilots, but a large aft door facilitates cargo access and egress.

The larger door also helps when the Viator is used as an air ambulance when litters must be loaded, while parachutists can safely jump from behind the propellers. But increased speed has not been achieved at the expense of higher maintenance costs.

In fact the Viator has been designed to have a long service life with minimum maintenance requirements. In addition to benefits derived from its simple rugged structure, the Viator has a high prop tip clearance that considerably reduces foreign object damage. Also, the nose cone opens downward to allow quick access to hydraulics and avionics, cutting inspection and maintenance time considerably.

Versatility has been built in to the Viator so that customers may opt for a front and/or rear camera hatch that can also be used for dropping emergency packs. Other special mission applications for the Viator include border or offshore patrol and surveillance carrying two sensor operators at display consoles in addition to two pilots.

Fitted with a nose-mounted forward-looking infrared camera and a belly-mounted radar antenna, the Viator can be dedicated to maritime patrol duties. In that guise the aircraft has an endurance of five hours flying at 5,000 feet at 160 knots.

The rugged landing gear and excellent short-field performance enables the Viator to be operated from unprepared strips and make use of remote and seldom used airfields. To clear a 50-foot obstacle, the Viator needs only 2,034 feet to take off and a landing distance of 2,297 feet.

Planned improvements to the Viator include an updated avionics suite for which a glass cockpit will be offered shortly. A modern oxygen system will also be available to facilitate high-altitude flying.

The Viator is being offered at an introductory price of $1.17 million and appears to be well positioned to compete with single-engine turboprops.