Military pilots are trained for and thus accustomed to flying airplanes with thrust enough to slap the eyeballs back into their sockets. Blackhawk’s new XP140 conversion for the staid Cessna Caravan doesn’t quite deliver that kind of punch, but there’s a hint of it from the lofty left seat.
Blackhawk has had great success in plying the niche of Pratt & Whitney PT6A-powered airplanes that the factory just didn’t get quite right for lack of available power or just marketing considerations.
Blackhawk’s latest project replaces the OEM PT6A-114 or -114A (600 or 675 HP respectively) with a -140 free turbine rated at 867 HP. While the conversion isn’t cheap, Blackhawk is selling into a market where the airplanes earn their keep with revenue flights and the additional performance rings the cash register.
The Upgrade Market
Engine mods and upgrades have been mainstays of the GA aftermarket since shortly after Charlie Taylor built the last Flyer engine. As the piston market cooled in the 1990s, the turbine aftermarket heated up with several companies offering mods to popular airplanes like the King Air series, Cessna’s turbine twins, Piper’s Cheyennes and more recently, the Cessna 208 Caravan.
Waco, Texas-based Blackhawk came into the market in 1999 and now offers PT6A upgrades for the Beechcraft King Air 90 and 200 series, the Conquest I and the Piper Cheyenne. When we visited Waco last December, Blackhawk was working on a PT6A-67A mod for the King Air 350.
For the Caravan, Blackhawk offers two options, both available for the 208A and 208B models. Its first foray was the XP42A, which swaps the airplane’s existing -114 or -114A for the 850-HP PT6A-42A. Because that engine is larger and has a different footprint than the powerplant it replaces, the XP42A conversion gets a new fiberglass cowling as part of the conversion kit. It also gets a new four-blade Hartzell prop, a new mount and engine exhaust outlets.
The follow-on product, which achieved STC approval last year, is the XP140, which includes a slightly more powerful engine, but one which will easily fit into the existing cowl with minimal modifications to the airplanes.
“No modification is really a bolt-up, but this one comes as close as any I’ve seen,” said Bob Kromer, Blackhawk’s senior vice present for engineering. The XP140 retains the original cowling and requires only a single exhaust. Rather than a four-blade prop, it gets a new three-blade model.
Exchange Motors
Kromer told us that with more than 2500 Caravans flying, there are many hundreds motoring around with tired PT6A-114/114A engines in need of overhaul. Since these are almost universally working airplanes, Blackhawk’s pitch to these owners is why spend money on an overhaul to get the same performance when you can spend a little more and improve performance dramatically.
“A little more” is relative. Caravans on the used market vary widely in price. A 15-year-old airframe with a run-out engine in presentable condition retails for between $600,000 and $700,000. The XP140 engine kit, all inclusive, sells for $604,000, plus another $25,000 in labor to install it.
To sweeten the deal, buyers are offered a $50-per-hour credit for engine cores that are below the 3600-hour TBO. The 600-HP -114 gets $34 per hour in credit. “If you flew your engine to 3600 hours, there are no credits for your exchange and that’s built into the price. If you’ve got an engine with 500 hours on it, it’s worth money as a credit,” Kromer said. (The cores go back to Pratt for overhaul.)
Kromer tells owners that adding another $200,000 for paint and avionics upgrades will bring the total to about $1.4 to $1.5 million, or a million less than a factory-new equivalent.
Cessna currently offers two versions of the 208, the Caravan and the Grand Caravan EX. The Caravan is the smaller of the two, at 37 ft. 7 in. in length with a gross takeoff weight of 8000 pounds. It uses the 675-HP PT6A-114A Cessna switched to in 1990 from the 600-HP -114. The Grand Caravan EX is 41 ft. 7 in. long with a max takeoff weight of 8807 pounds. The Grand Caravan EX, which became available in 2013, has the same PT6A-140 Blackhawk uses.
Blackhawk’s secret sales sauce is that its conversion applies to all of the Caravan models, including both the 600- and 675-HP variants.
“Obviously, the guys upgrading from the 600-HP airplanes will notice the biggest performance difference,” Kromer told us. Not that the step up from the 675-HP engine is exactly a slug, as we learned on our flight trial. Blackhawk can modify all of the Caravan models except those equipped with factory-installed Garmin G1000 suites; Cessna retains a lock on the software for those models and Blackhawk can’t tap into them for the engine instruments.
Field Installs
Blackhawk’s Waco shop is primarily a skunk works, so most of the installs are done in the field by businesses Blackhawk has trained or overseen. The kit includes the new engine, exhaust system, new prop, a 325-amp Ametek starter/generator, a larger-capacity oil cooler and new engine instruments from Howell Instruments.
Kromer told us the typical installation requires two technicians and an electrical specialist and requires about 10 working days. Many customers add paint and avionics work to extend the schedule. The engine carries the standard Pratt & Whitney new-engine warranty.
Although the airplane retains its original weight and payload numbers, it’s approved for floats and given the additional horsepower, we suspect the performance on high-density altitude lakes and rivers is much improved over the original, especially when the starting point is the -114 engine. The props are equipped with zero locks (and Beta range) so the only residual thrust at idle is from the exhaust.
Flying It
We demo’d the XP140 test article at Blackhawk’s Waco headquarters on a foggy fall day. It’s easy to compare the takeoff and climb performance by simply setting the new engine’s torque values to those of the PT6A-114A it replaces. The Howell gauges are a combination analog/digital display that makes both coarse power setting and tweaking doable on the fly.
For the first flight, we took off from Waco and climbed unrestricted through an overcast to 10,000 feet. At a mid weight, the Caravan accelerated briskly on the runway and after rotation, we held the climb at 110 knots indicated.
According to the timer, we reached 10,000 feet in 9:35. Leveling out, we calculated the true airspeed to be 171 knots on a fuel flow of 329 pounds or 47.7 GPH. The max ITT was 765 degrees for a torque value of 1865 pounds. This performance matches the OEM -114A engine.
For the second flight, we repeated the same profile, albeit at a slightly lighter weight due to reduced fuel. Runway performance was dramatically improved and we felt the propwash pulsing in the rudder pedals. With the additional power, it takes effort to hold the 110-knot best climb speed because the deck angle is noticeably higher.
And, of course, so are the torque and fuel flows. Max torque was 2397 pounds and fuel flow in cruise was 434 pounds (65 GPH). Although most engine power upgrades don’t produce much additional speed, the XP140 does, by dint of the optimized prop.
Cruise speed at 10,000 feet was 180 knots TAS and we reached that altitude in 6:25. It would have been a little quicker if it hadn’t been so challenging to hold 110 knots in the climb. From brake release, the XP140 averaged 1550 FPM in climb, against 1047 FPM for the OEM engine.
To extend their utility, many Caravans have cargo pods installed, but the test article we flew did not. Based on Blackhawk’s claimed performance data for the two engines, the numbers we saw were in line with the claims. In addition to the faster climb, the takeoff performance is also better.
Blackhawk documentation claims a 3086-foot takeoff run over a 50-foot obstacle (1602-foot ground run) on an ISA -10 day at 8300 pounds total aircraft weight. That’s for a baggage pod-equipped airplane. The OEM engine in the 208B delivers 3650 feet over the obstacle for a ground roll of 1965 feet in the same conditions. Overall weight and balance remains unchanged from the original aircraft.
However, what Pratt giveth, Pratt also taketh away, albeit not much. More speed and power translate to higher fuel flow. We asked Blackhawk’s Kromer if owners of these mods take advantage of the ability to throttle them back to lower power settings to save fuel. He said owners tend not to. If they’re buying that power, they want to use it. Fuel consumption is a secondary concern. At max cruise power, the XP140 mod has a still-air range of 825 miles at 12,000 feet while the OEM -114A it replaces will stretch to 900 miles. This is not likely to be much of a factor for most operators because they’re buying the conversion for its rapid climb rate and improved short field performance, not long legs. In a pinch, the -140 can be pulled back to extend range.
Which get us to the principal market for the XP140: skydiving operations. With the faster climb rate, drop zone operators can do nearly two extra revenue loads per hour, which translates to higher earnings and makes the considerable investment more attractive.
In our view, by investing as much as it has in the XP140, Blackhawk has positioned itself in a unique niche, giving it the ability to match and even exceed new factory airplane performance at a fraction of the cost. We see this as yet another datapoint in a trend of more refurb and mod projects as new aircraft prices escalate and sales volumes decline.
See a video review of the XP140 on Aviation Conumer‘s YouTube channel.
