Bizjet and TP modifiers
Mods and upgrades improve aircraft performance and add value.
Owen Davies
Contributing writer
In recent editions of Professional Pilot magazine, we have looked at companies that maintain, repair, and overhaul executive aircraft. This time, we are going to examine firms that modify business jets and turboprops (TPs). These companies can improve performance, reduce maintenance costs, and cut fuel burn and the resulting pollution for many aircraft types. One company delivers what amounts to a whole new aircraft. Here is a brief look at 5 of the top performers in the aircraft upgrade segment.
Aviation Partners, Inc (API)
API has specialized in winglets since it developed the blended winglet – the first to emerge from the wingtip at something other than a 90º angle. They were a big step forward in winglet design.
Unlike their predecessors, API’s blended winglets emerge from the wingtip and bend upward in a large-radius curve with a smooth chord transition through the curve.
They are 60% better at reducing the tip vortex than straight-up tips. They were introduced for the Gulfstream II in 1992, and ultimately were installed in 70% of the GII fleet. At this point, they are flying on more than 8000 business jets and commercial aircraft.
Looking at the details, it becomes clear why aircraft operators have accepted them so enthusiastically. On Dassault Falcon 2000, 900, and 50 series jets, they yield a 5% range increase at M.80, and 7% at long-range cruise.
They also provide a faster climb to altitude and a 2000-ft higher initial cruise. They even reduce emissions significantly and offer 75% residual value according to blue books. And for the Hawker 800 series, they offer 7% fuel savings while providing 180 nm more range and improving stall characteristics.
Working with Boeing, API later combined aerodynamic elements of ventral strakes, scimitar tips, and trailing edge wedges to create the Split Scimitar Winglet (SSW.) It resembles a standard blended winglet, although with a second, smaller airfoil projecting roughly 45º down from the curve to the wingtip. The SSW reduces drag another 2% or more.
As API points out, it gives a 7-aux-tank BBJ the range of one with 8 aux tanks. The new winglets became standard on all new Boeing 737 NG BBJ aircraft in 2015 and are now in service on around 1500 737 NG airliners.
For a simple-sounding idea – ”Let’s just use a curved joint instead of a right angle” – API’s Blended Winglets have made a sizable impact on business and commercial aviation.
Blackhawk Aerospace
At first glance, Blackhawk might appear to be a conventional MRO. It can handle all the regular maintenance, repair, and overhaul work, and does so on a daily basis.
Less commonly, the company also holds STCs for installation of retrofit avionics in Cessna, Gulfstream/Astra, Learjet, King Air, and Hawker aircraft. However, when it comes to aircraft mods, Blackhawk is known for adding one thing to TP aircraft – horsepower.
It specializes in swapping out original Pratt & Whitney Canada turbines for new, bigger, more efficient models. Upgrades are available for most King Air, Cessna Caravan, Grand Caravan, Conquest 1, Piper Cheyenne, and Pilatus PC-12 TPs under an STC held by Finnoff Aviation Products.
Engines can be mated to upgrade props from MT-Propellers, McCauley, and Raisbeck/Hartzell. Also available are the Raisbeck Ram Air Recovery System, Enhanced Performance Leading Edges, and Dual Aft Body Strakes; plus a variety of other 3rd-party items.
The XP135A is a typical Blackhawk upgrade King Air 90 aicraft. It swaps out the original P&WC PT6A-21 engines with PT6A-135As. The change adds 36% more available horsepower. Cruise speed goes from 211 KTAS for a C90 to 260-plus KTAS, and from 234 KTAS for a C90A/C90B to 270-plus KTAS. Single engine service ceiling rises to FL190. Operating costs decline by 10%.
The upgraded King Air 350/350ER gets new PT6A-67A engines that produce 1050 SHP at up to FL250, 10,000 ft above the altitude where the stock engines begin losing horsepower. With new 5-blade composite props by MT-Propeller, max cruise exceeds 320 KTAS, with a 60% increased climb rate. The aircraft has a 62% greater payload than a Citation CJ2 with max fuel. Operating costs drop by $90,000 per year.
Cessna Caravan and Grand Caravan operators can opt for a new PT6A-42A powerplant, yielding 189-plus kt max cruise and a 3600-hr TBO, or the PT6A-140 for 195-plus kt max cruise and 4000-hr TBO.
Blackhawk’s new upgrade for the Pilatus PC-12 swaps out the original PT6A-67B of 1200 shp for the more efficient PT6A-67P used on the PC-12NG. Unlike the 67B variant, which begins to lose horsepower at FL150, the -67P can maintain full power to FL250. The company had contracts and deposits from 5 customers more than 6 months before the expected certification.
Add 2 more benefits to this list – a great warranty and a great resale record. Upgrade engines carry the P&WC Enhanced New-Engine Warranty. It offers full coverage for 2500 hours/5 years and prorated coverage to the 3600-hour TB0. And Blackhawk upgrades hold their value. According to the company, nearly every Blackhawk-powered aircraft sold within 500 hours of the upgrade recovered close to or more than the combined investment of the airframe and engines.
In all, it is clear why TP operators have given Blackhawk’s upgrade packages an enthusiastic welcome.
Nextant Aerospace
This company has a unique approach to aircraft modifications. It takes an existing aircraft, carries out a whole-plane upgrade, and markets the plane – or returns it to a customer – with its own model name and FAA-certified production number. Upgrades typically include new engines and avionics, aerodynamic enhancements such as raked winglets, and a custom interior.
At the bottom of the line, a stock King Air G90 enters the process and a Nextant G90XT emerges. On the way by, it gets new GE H75-100 high-efficiency engines that generate more power on less fuel with a 4000-hr TBO and no hot-section requirement.
It’s also fitted with a Garmin G1000 integrated flight system and a redesigned cabin with more volume than the original. Winglets and Raisbeck Aft Body Strakes and nacelle lockers are optional upgrades.
Higher in the line, Nextant offers the 2+7/9-pax 400XTi, based on the Beechjet 400A/Hawker 400XP. After 6000 man-hours of remanufacturing, all that is left of the original aircraft is the airframe. Nextant adds Williams International FJ44-3AP high-efficiency FADEC engines, 4-display Rockwell Collins Pro Line 21 avionics, XTI Shark Fin winglets, and an enlarged, redesigned cabin.
Nextant’s upgrades improve performance significantly. The G90-XT offers a cruise of up to 17 kts faster than the C90GT, with 10% better fuel burn, 10% longer overhaul time, and lower maintenance costs. Range with 4 pax extends to 1163 nm. Meanwhile, the 400XTi provides a high cruise of 460 kts, 2300-lb payload, and a range of 1925 nm with 4 pax.
Other models in the company’s lineup include the 400X and 400XTe, based on the comparable Beechcraft/Hawker jets, and the 604XT, derived from the Bombardier Challenger 604.
Nextant Aerospace has come a long way since it introduced the concept of aircraft remanufacturing to the bizjet market in 2007. Its offer of better performance at as little as half the price of new has proved a winning combination for many business operators.
Raisbeck Engineering
“My greatest satisfaction is improving the productivity and performance of an airplane that is owned by a lot of folks, where they appreciate the improvements,” said Founder James Raisbeck in a 2016 interview.
He must have earned a lot of it. That year, some 6200 Beechcraft King Airs were flying. Just under 4000 of them – roughly 2/3 – carried at least one Raisbeck upgrade.
Today, his company offers a wide range of systems for King Airs. The Raisbeck Swept Blade Turbofan Propeller System includes 96-inch 4-blade aluminum propellers and 105-inch 5-blade composite props. They improve performance in all flight regimes and reduce cabin noise by up to 1/3. Some models reduce weight by up to 41 lb compared with standard props.
Raisbeck Enhanced Performance Leading Edges, also composite, eliminate airflow separation and reduce drag. They improve takeoff performance and reduce stall speeds by a few knots at all flap settings.
Wing-to-body vortices normally disrupt airflow under the King Air’s aft fuselage, creating needless drag. Raisbeck’s Dual Aft Body Strakes eliminate airflow separation under the aft fuselage, improving climb and cruise performance and directional stability. They now come standard on King Air 350, 360, and C90GTx aircraft, and are available as factory options for other models.
The Ram Air Recovery System redirects airflow under the cowl, helping the PT6-42 engines breathe better and reducing interstage turbine temperature by as much as 18° C.
The Ram Air Recovery System, high-performance props, Dual Aft Body Strakes, Enhanced Performance Leading Edges and other modifications are available as packages for King Air models and the Cessna Caravan.
Tamarack Aerospace
Unlike other aircraft modders, Tamarack offers only one product. It makes winglets for Cessna Citation bizjets and other aircraft. From a distance, they look like any curved-interface winglet, but they aren’t like the others, because they’re are active winglets. Unlike the competition, Tamarack’s winglets carry their own computer-operated control surfaces, known as the ATLAS load alleviation system.
The system automatically controls wing bending during turbulence and other stressful events. The winglets operate independent of other systems and add nothing to the pilot’s workload. The benefits are impressive. A Citation M2 Gen2 equipped with Tamarack’s Active Winglets can accelerate to cruise speed in 8 minutes or less, and climb to FL410 in 22 minutes or less at max takeoff weight. A CJ1+ at MTOW gets to FL410 in 32 minutes or less. A wing equipped with active winglets undergoes less stress, reducing maintenance costs and extending wing life.
Yet, for most operators the real attraction is fuel savings. In 2021, a stock Cessna Citation Jet raced one with Tamarack’s winglets from PWM (Portland Intl Jetport, ME) to PBI (Intl, West Palm Beach FL). Despite a deliberate 200-lb weight penalty, the winglet-equipped plane reached Palm Beach in 4 hours 35 minutes. The standard bizjet took 5 hours 37 minutes with a fuel stop at Columbia SC. “Depending on conditions, our Citation Active Winglet mods can deliver up to 33% fuel savings,” says CEO Nick Guida.
Thinking of airliners, AirInsightGroup titled a recent article “Fuel saving technology could cut new aircraft demand.” Tamarack already provides active winglets for a variety of airliners, offering some 15% better fuel economy. “Second only to sustainable aviation fuel, our active winglets can do more to reduce aircraft pollution than any other technology out there,” adds President Jacob Klinginsmith.
He noted one other benefit as well. Because active winglets stabilize aircraft on approach, they make the most mishap-prone part of any flight safer. “Some customers buy the system because their families will be onboard, and they want to keep their wives and kids as safe as possible,” he adds. “For them, the fuel savings are gravy.”
These are 5 innovative companies that add speed, efficiency, safety, environmental friendliness, and value to aircraft. For relatively small firms, they are having a big impact on business and commercial aviation.
Owen Davies is a veteran freelance writer specializing in technology. He has been a futurist at Forecasting International and TechCast Global.