Another player has joined those offering engine upgrades on the Cessna Caravan. Earlier this summer, Blackhawk Modifications (Booth No. C6516) received FAA supplemental type certificate (STC) approval for its conversion that replaces the aircraft’s stock 675-shp Pratt & Whitney Canada PT6A-114A with an 850-shp PT6A-42A. The company is ramping up to do three conversions per month and estimates installation time at two weeks.
Blackhawk now joins Alaska-based Aero Twin and Texas Turbines in offering an STCed turbine retrofit for the Caravan. The former use the Honeywell TPE331-12JR engine and develop 850 to 950 shp. Both the Honeywell installations and the Blackhawk retrofits include the capability for flight–into-known-icing approval.
Aero Twin was the first to receive STC approval for the TPE331 and offers it rated at 850 shp for the Caravan and 950 shp for the Grand Caravan. The $720,000 conversion includes the engine, new propeller, a battery tender and a new standby vacuum pump. The old engine, propeller and other parts are returned to the customer. “It is easier and cleaner if the customer does all of that themselves,” said Brian Goode, the company’s sales director.
Jason Kepler, Aero Twin’s chief engineer, said his company’s engine installation, canted to the left and down, virtually eliminates P-factor on takeoff rolls. “You basically take off with your feet on the floor even though you have 950 horsepower.” Kepler also noted that the single power lever and automatic torque and temperature limiting sensors on the engine significantly reduce pilot workload on takeoff. “You don’t have to be staring at your torque gauge all the way down the runway.”
Texas Turbines received its STC for its “Supervan 900” conversion in 2008 and has sold approximately 20 to date, said company president Bobby Bishop. Installations take place at Texas Turbines or at authorized dealers in the U.S. and abroad, including Banyan Air, Intercontinental Jet, Wipaire, CJ Aerospace (Australia) and Air Alliance (Germany). Bishop said conversion customers run the gamut from high-net-worth individuals to commercial operators to sky diving schools, the latter representing approximately 50 percent of his business to date. The $570,000 conversion cost is based on the exchange of a stock run-out PT6A-114A and includes an engine core credit of approximately $100,000.
Bishop said the Honeywell engine had distinct advantages over the stock Pratt in the 208 including a 7,000-hour TBO, halving runway requirements; four to six fewer gallons per hour fuel burn at the same speed; 12 to14 knots faster with the same fuel flow,or 35 to 40 knots faster “if you don’t care about fuel.”
Blackhawk spent $3 million and 35,000 man-hours developing the P&W conversion which costs $605,000, assuming engine core trade-in. It includes a new composite cowling, twin Frakes exhaust stacks, new oil cooler, new engine gauges, a new 100-inch Hartzell four-blade propeller and enrollment in the Camp Systems maintenance tracking system. The new oil cooler is 40 percent larger than the one it replaces, particularly useful in hot climates where stock Caravans idling with their prop in feather can easily exceed maximum oil temperatures, particularly in the Middle East.
The converted aircraft also is approved for flight-into-known-icing conditions. “With the stock engine, when you load up with ice, you are going to start drifting down,” Blackhawk president Jim Allmon said. “We tested this airplane for an hour with over five inches of ice on it. The slowest speed that we could maintain at full power was 170 knots.” As part of the test regime it also did 115 spins.
Blackhawk initially has 20 orders for the conversion, with heavy interest coming from the skydiving market. Allmon said the conversion in the 208B will allow skydive operators to carry an additional three to four jumpers per hop and fly an extra one or two jump runs per hour. “One skydive operator told me that his [converted] airplane would make enough money in one season” to pay for the cost of conversion. “His income will almost double,” Allmon said.
All of the conversion providers noted that the retrofit could be done only to legacy aircraft as Garmin has yet to provide engine parameter data on its G1000 avionics system in newer Caravans. They also all said that they expect demand for their conversions to increase substantially once the 208B Grand Caravan is certified for float operations.