Caravan-On-Steroids Sports 900 SHP And A Texas Performance Attitude To Match

It is hard to believe the Cessna Caravan first rolled off the assembly line 25 years ago. By 2005, the total operating fleet worldwide had mushroomed to some 1,500 aircraft, amassed more than 8 million flight hours at a rate of more than 71,000 hours per month, and FedEx claimed to be operating its aircraft at a 99% dispatch rate.

The Caravan has certainly earned the right to call itself one of the most successful general aviation designs, but as well all know, aircraft ownership comes with a price. To make money you have to spend money, and the Caravan is no exception to the rule. With a 3,600 hour TBO, the Pratt and Whitney powerplant eventually needs to be overhauled or replaced. Depending on the condition of the engine, an overhaul can cost anywhere from $200,000 to $300,000 minus the core credit. If you want to go new, the replacement can set you back a cool $400,000.

There is another aspect of the Caravan that also comes to play in deciding what to do with the engine. 675 shp is no slouch for a single-engine aircraft, but many Caravan operators fly this aircraft in what can only be described as challenging conditions. After all, the aircraft was originally designed as a bush aircraft. In high density altitude and high temperature conditions, or in distance-challenged takeoffs, the aircraft can leave operators wishing they had an option for that little extra "oomph" that might make the difference between a successful takeoff and lopping off the tops of trees in the Amazon jungle.

Over the years a number of suppliers have come up with upgrades to improve the aircraft's performance. Blackhawk Modifications recently announced their PT6A-42A upgrade to 850 shp, and AOG Air Support offers its AOG Hot Wings wing design modification.

Texas Turbine Conversions decided to enter the fray and design a completely new firewall-forward package, but they chose to use the Honeywell TPE-331-12JR engine and a Hartzell 110" four-blade propeller, as well as a some panel, electrical and other minor modifications.

Aero-News interviewed Texas Turbine Conversions' Bobby and Kim Bishop, the husband and wife team behind the company, to get the details of this program and the value proposition they offer to their customers.

Since the company does not overhaul engines, its upgrade is only for new TPE-331 engines. The -12JR is rated at 1,100 shp but for this installation they are derated to 900 shp. The conversion package is priced at $645,000, not counting core credit. Because PT6A-114 and -114A cores are in high demand, they can fetch between $100,000 and $400,000 depending on condition.

For the purposes of this analysis, we assume a run-out engine at the bottom of the range. That said, simple arithmetic brings the net cost of the package (not counting down time, ferry, etc.) to roughly $545,000.

The result of testing has revealed that you not only get more power out of the conversion, you get a fuel consumption savings at cruise power settings of about three to four gallons per hour. If we compare TBO to TBO, that means that over what should be the useful life of a PT-6A-114 with a 3,600 hour TBO, the operator should save around 10,800 to 14,400 gallons of fuel.

To place a valuation on that, Aero-News chose the price of Jet-A at KINK (Wink, Texas), a popular fuel stopover for east- and west-bound aircraft, currently $3.72 per gallon, resulting in savings of $40,176 to $53,868. This is a simplistic calculation, but you get the idea. Spot prices for jet fuel peaked in June 2008 at more than three times current pricing, and if it happened before, it can happen again.

However, TBO comparisons don't stop there. The TPE-331-12JR has a TBO of 7,000 for commercial operators and 5,000 hours for non-commercial operators. That represents almost 100% additional useful life for the engine for commercial shops, and therefore 100% more time to make money with the equipment before you have to lay out another chunk of cash and four weeks of down time.

To the pilot, performance is the bottom line, and here the Texas Turbine Conversions package truly excels. Noise levels are higher on the ground because of the well-known high pitched noise of the Honeywell engine, but noise levels in climb, cruise and descent are reduced some three decibels because the prop operates at a slower 1,591 rpm. Cabin noise is also lower, for the same reason. Basic takeoff performance is reduced from 1,405 feet to 1,054 feet, and distance to clear a fifty foot obstacle is reduced by an impressive 25% to 30%, from 2,420 feet to 1,875 feet. The conversion improves climb performance by over 60% at lower altitudes and over 100% at 10,000 feet. According to the company, it takes just under thirteen minutes to climb to 14,000 feet MSL on a 35°C/95°F day at a takeoff weight of 9,000 pounds. Climb performance at gross weight and ISA increases from 975 to 1,510 feet/minute. Cruise speed at equivalent flow settings improve by as much as 15 knots.

What this all translates to, according to customers who are operating the aircraft, is faster turnarounds, along with a 312 pound increase in gross weight, 100 pounds of those coming from the engine conversion and the rest tacked on to useful load. The lower fuel consumption translates to longer endurance and a max range of 1,000 nautical miles as opposed to 915 for the stock Caravan.

All in all, this has all the signs of a very profitable value and performance proposition for operators who can use this kind of performance, and that translates to a direct positive impact on the bottom line. So far the company has received certification for the 208B on wheels. They are finishing the testing on the 208 amphibious and wheels Caravans, and expect to receive the paperwork from the FAA in the first quarter of this year.

Certification for the 208B on floats is expected in the fourth quarter of 2009.

FMI: www.texasturbines.com