Ag aviation embraces V8 power

by Bill Lavender

by Bill Lavender One of the great aspects of publishing AgAir Update is the opportunity to fly various, often very unique, ag aircraft. With all my evaluation flights, I've tried to make it clear there is no single evaluation flight that can take the place of operating the aircraft 50 or more flight hours.

An evaluation flight that has been in the making for over two years finally came to fruition, the Orenda-powered Air Tractor AT-401. This all-new 600 horsepower V8 powerplant by Orenda Recip, Inc., a Magellan Aerospace Company subsidiary located in Ontario and Nova Scotia Canada, has promised to deliver turboprop performance at a reciprocal engine price. In the right context, I believe that to be true. Before we examine the flight, let's take a brief look at the history of the Orenda engine.

The Orenda engine's birth was as the Thunder engine, a project started in California. Eight years ago Orenda bought the design and manufacturing rights for the engine and began an extensive computer-assisted design (CAD) redesign. Incorporating liquid-cool and turbocharger technology, along with six-bolt main bearings and cast iron cylinder sleeves, the Orenda engine promises to offer durability while being affordable.

The Orenda OE600A engine was certified by Transport Canada on March 19, 1998 and FAA certification was issued in March 1999. In addition to several other agricultural aircraft planned, including the Thrush, Orenda's current aircraft application include the King Air C90, Z-400 Rhino utility aircraft, Explorer 500R utility aircraft, DHC-2 Beaver, N5A Hongdu agricultural aircraft and the Turkish Aerospace ZIU agricultural aircraft. The Orenda powered DHC-3 Otter was certified in January 2000.

With the Air Tractor 400 series, at $150,000 USD, installed turnkey/ready to fly, price-wise the ag aviation operator's capital costs lie somewhere between the overhaul costs of a typical ag-aircraft piston and turboprop engine.

Orenda's closest competitor for an airframe revamp is a turboprop conversion at approximately $50,000 more. While its least expensive competing option is a $30,000 plus overhaul of an existing radial installation, without an upgrade in performance. The Orenda engine is advertised to have a certified TBO of 1,500 hours, to be extended to 2,500 hours. Although the Orenda engine has not yet been in service long enough to reach its certified TBO of 1500 hours, a de Havilland Otter in Canada is quickly approaching TBO, while the Air Tractor I flew had accumulated almost 200 hours, all maintenance free.

The Orenda engine is manufactured from all-new certified aviation components using the latest technologies. Engineered for the STC by Orenda, the mating of the Orenda engine to the AT-401 simply could not have been done any better. The AT-401 STC was issued December 2001, and the multiple Air Tractor 400 series aircraft STC was issued June 2002. Neatly tucked under the sleek aerodynamic cowling of the AT-401, a pilot could easily mistake it for some new design turbine-powered Air Tractor.

When arranging the flight evaluation, I was contacted by Orenda's Derek Parker, Sales and Marketing manager. He explained the Orenda Air Tractor would be at Bob Davis Flying Service in Illinois. I knew the Orenda had all the promise of a good, quality installation. All that was left was to fly it and see just what it could do.

Upon arrival at Bob Davis's, I immediately understood one of the reasons why Orenda elected to have Bob Davis market the Orenda installation in the U.S. Bob has one of the cleanest operations that I have had the pleasure to visit. With its drive-thru, covered loading facility and containment system, it was obvious Bob runs a first class operation.

Bob Davis was one of the first, 12 years ago, to have his containment facility certified by the state of Illinois. He also owns Davis Aviation, with a second location in Tennessee, which holds the Bonaire 550 upgrades, offering the Continental IO-550 conversion for the Cessna 188 series ag aircraft. Davis Aviation also offers various engine and propeller upgrades for aircraft such as the Cessna 185, 206, T206, 207 and T207, as well as "heavy duty" engine mount upgrades for the Cessna 180 and 182.

Always thinking ahead, Bob Davis became involved with the Orenda project four years ago when he provided the Air Tractor airframe as a prototype for the Orenda engine installation. With Bob's 28 years experience in the ag aviation industry and an STC holder himself, Orenda has made a wise choice to seek his assistance.

The Orenda engine is rated at 600 horsepower, of which 500 are max-continous. It weighs approximately the same as the R-1340 engine, however has the aerodynamics of a turbine engine aircraft. I was told to use full power for takeoff, with no restrictions. It was an 80¡F day, thus there was no concern about over boosting the manifold pressure. The preferred power settings for working are 40 inches of manifold pressure at 2,000 prop rpm with a load and anything less for a lighter load. The 2,000 prop rpm equals 4,000 engine rpm with the 2:1 gear box reduction. Using 40/2,000 for a power setting is utilizing about 400 horsepower and burning about 45 gallons of 100 LL av gas per hour according to the fuel flow meter. Eagle Aviation in Arizona has been reporting fuel consumption with their Orenda-powered Air Tractor at 36 gallons per hour.

As with almost all my evaluation flights, I like to make the first flight empty. After that exhilarating ride, I returned to fill the hopper with 200 gallons of water, and again the third time with a full tank of 350 gallons.

Upon landing, I noted a slight float with the throttle retarded all the way to the stop. Although the prop is full feathering, it does not have a beta function that would help with extreme short field landings. In any case, I had no problem landing in a no wind condition on about a third of Bob Davis's 2,600-foot sod strip.

Takeoffs were exceptional. Empty, of course, was like any ag plane, holding on to a homesick angel. Not much difference with 200 gallons, maybe a couple of hundred more feet on the roll out before rotation. Even with 350 gallons, the aircraft took off confidently, breaking ground before mid-way (1,300 feet) and climbing comfortably. There's no denying, you could feel the 350 gallons were in the hopper. I had to be a little more gentle with the controls, probably as much from my lack of experience in an AT-401 as much as anything (old Thrush pilot). The response of the aircraft was comparable to a turbine AT-402. Airspeed would pick up quickly upon entry into the field, and bleed off slower on the breakout from the field than with the radial version AT-401. With the sleek aerodynamics of the Orenda installation, this is to be expected. If there was any measurable difference in the performance of a normally operated turbine (using 400 shp), it would be due to the extra weight of the Orenda. However, I found the torque of the engine was such that takeoff performance was similar to a PT6A-15 engine powered AT-402. In essence, the turbine versions of the AT-400 series aircraft are very similar in performance to the Orenda, with the exception of the 750 shp PT6A-34. The performance of the Orenda compared to the radial version AT-401 is notably better.

It's a numbers game, comparing the Orenda with other AT-400 series aircraft. The numbers get decidedly better if one assumes Orenda will receive the TBO extension to 2,500 hours. Orenda's numbers are 50% less capital investment and 30% reduction in operating cost. My assumption is they are comparing the conversion of cost of the Orenda with that of a new PT6A engine and prop; probably a fairly accurate claim.

The 30% reduction of operating cost has to come from primarily the overhaul cost per hour operated. To overhaul the Orenda, in today's dollars, at 2,500 hours, is estimated to be about $30,000, or about $12 per operating hour. Orenda doesn't anticipate any significant maintenance cost between overhauls, with the exception of oil, filters and spark plug changes. Therefore, the savings realized would have to come from an amortization of operating expense between overhauls to a per hour amount. The turbine engine's hourly operating expense is closer to $25- $35 dollars per hour between IRANs (Inspect and Repair As Necessary).

Of course, there should be a savings in insurance cost, as the hull value of the aircraft would be less than with a turboprop installation. Also, cost of money would be less with less capital investment into the conversion. So, why would anyone not buy an Orenda engine for an upgrade in performance for their AT-401, and reduced operating costs compared to a turboprop? The performance is comparable, and the apparent operating cost are less. There's still the issue of reliability and support.

Orenda is experiencing good revues from the engines that are in service. However, the PT6A engine has many years of proven performance. Once achieving a track record similar to the PT6A, Orenda will have reached a significant benchmark.

An Orenda-powered Air Tractor AT-401 has been successfully operating commercially at Eagle Aviation in Mojave Valley, Arizona since early August of this year. Eagle Aviation's Bill Dare has been conducting ag ops (spray and fertilizer) in ambient temperatures of 110¡F with all the temps of the engine in the "green". Bill Dare's biggest complaint is that "the aircraft is too fast". He says, "It's a rocket!" Operating and landing speeds are equivalent to a turbine powered Air Tractor.

As for support, already, Orenda is negotiating with several companies in the U.S. to operate as service centers for the engine conversions. For the immediate future, Orenda is installing the conversions, maintaining tight quality control for its product.

Any time an operator has more than one choice for a powerplant for his aircraft, he is in a better position to make his operation profitably. Each operation has its own unique needs, thus dictating which engine is best. For many, the Orenda engine will fill their needs and increase their profit margin. Orenda is world renown and has the financial stability and reputation to support the engine. Converting the AT-401 to the Orenda engine should be a viable option for many ag operators, worldwide, permitting turbine performance at an affordable cost.