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Performance mods and remanufacturing


Upgrades increase business aircraft value and enhance safety.

By Shannon Forrest
President, Turbine Mentor ATP/CFII.
Challenger 604/605, Gulfstream IV, MU2B

Raisbeck Engineering’s aft body strakes reduce drag by shedding wing-to-body vortices captured under the aft fuselage.
Every company that has a product to sell profits from a customer’s desire to own something different or his urge to enhance an otherwise basic product. In advertising, it’s known as the “upsell.” The mere power of suggestion (eg, “Would you like fries with that?”) triggers a compulsion to buy. Sometimes it’s about perceived value.

The bartender offering to make your cocktail a double for just a dollar more closes that deal nearly every time. Automobile manufacturers upsell the notion of being unique.

New car salesmen will argue that, although blue is available at the advertised price, the car looks much better painted in urban mocha twilight (or some other fanciful name to describe a minor variation of blue). Of course, urban mocha twilight is a custom color, and therefore the dealership must charge extra for it.

Performance enhancements

In many respects, the upsell is not quantifiable because design aspects or judgements about value are subjective.

However, there is an exception. Performance enhancements can be measured against a known standard. In other words, if the specification of a base model is firmly established, any upgraded version that outperforms the original is, by definition, better.

Occasionally, it takes an entrepreneurial visionary to transform an off-the-shelf product into something special. Carroll Shelby is an entrepreneur esteemed by the auto racing community, but his background as a pilot often goes unmentioned.

Raisbeck’s Ram Air Recovery System comes standard on new King Air 250s.

Shelby graduated from flight school in the US Army Air Corps in 1942, and went on to fly Boeing B-17 Fortress, Douglas B-18 Bolo, North American B-25 Mitchell, Martin B-26 Marauder, and Boeing B-29 Superfortress aircraft during WWII.

According to Shelby, his favorite was the B-26 because it was faster in a straight line than enemy fighters at the time. When WWII ended, Shelby transferred his love of airspeed to groundspeed and became an auto racer. Eventually a heart condition sidelined him, so he went from driver to engineer.

During the 1960s Shelby created his own company and produced cars that won racing championships by outrunning Corvettes and Ferraris. Around the same time, the Ford Motor Company achieved widespread success with the Ford Mustang.

Sales were good, but Lee Iacocca, manager of the division that produced the Mustang, felt the car needed more performance. Iacocca turned to Shelby and asked him to upgrade a stock Mustang into something that appealed to high-performance enthusiasts. The rest is history.

Even today, a late-1960s Shelby Cobra GT500 is highly coveted, typically garnering $160–$180,000 at auctions in 2021. Shelby’s gift was that he could take a good product off the assembly line and make it great in the aftermarket.

Customers who purchase a Blackhawk Aerospace engine upgrade receive a brand new Pratt & Whitney PT6 engine. Blackhawk does not install previously overhauled engines.

Upgrading aircraft

The aviation equivalent of Carroll Shelby is James Raisbeck. After graduating from Purdue with a degree in aeronautical engineering and mathematics, he was hired by Boeing as an aerodynamicist. In 1973, he established his own company and went on to develop a wide range of aftermarket systems for commercial airliners.

Raisbeck also became active in corporate aircraft innovations which included wing designs for the Sabreliner 65 and Learjet. Although Raisbeck has a long list of accomplishments, including NBAA’s Lifetime Achievement Award for Meritorious Service to Aviation in 2002, in everyday aviation conversation his name is most often associated with one aircraft – the Beechcraft King Air turboprop.

Over the years he has developed a myriad aftermarket performance upgrades for the King Air product line. More than 6200 King Airs of all types are still in service since the first one was delivered in 1964 – coincidentally, the same year that Ford introduced the Mustang.

Of those, more than 2/3 have at least one Raisbeck Engineering product installed. Why the King Air is the focal point of so many aftermarket modifications might not be immediately obvious just from looking at it. Unlike other twin-engine turboprops, there’s nothing particularly striking about the King Air exterior.

A Piaggio Avanti, Beech Starship, or Mitsubishi MU-2 look sleek and sexy sitting on a ramp. Even a Cessna Conquest looks faster. But, as the saying goes, you should never judge a book by its cover. The King Air has an impeccable safety record, and the PT6 engine has the reputation of being nearly bulletproof.

The spacious cabin and large windows are popular with passengers. King Air pilots contend that the aircraft handles well. Flight departments love it because of its versatility and efficient operating costs. After all these years, the King Air is a known quality.

In one word, the aircraft is solid. And the wide range of aftermarket refurbishments take a solid airframe – albeit common-looking – and make it amazing.

Raisbeck offerings

Raisbeck Engineering offers King Air refurbishment as a package deal, but also provides individual improvements à la carte.

The 200 Series Epic Platinum Package, which is available for 250, B200GT, B200, and 200 models, illustrates what a combined option would look like. Aerodynamics are improved by replacing the factory-installed leading edges with composite materials that retain airflow and reduce drag during the takeoff roll.

The net gain is smoother rotation, lowered stall speed, and increased outboard wing life. Moreover, dual aft body strakes eliminate wing-to-body vortice separation, improving directional stability and passenger comfort. On the powerplant side, Raisbeck’s Ram Air Recovery System (RARS) redirects airflow to the engines, which improves climb and cruise performance.

The modification provides an 8% increase in available horsepower at altitude and a decrease of 18 degrees of interstage turbine temperature (ITT) at the same torque setting. Propeller upgrades consist of swept composite 5-blade or swept aluminum 4-blade models – both manufactured by Hartzell Propeller.

Raisbeck Engineering maintains full transparency in defining exactly how the enhancements will improve performance by publishing a series of charts on its website. The charts compare a factory (“stock”) aircraft’s performance with that of a Raisbeck Engineering upgrade package across a multitude of parameters.

Using the example of a stock King Air 200 model versus the company’s Epic Platinum Package, Raisbeck claims it can shave 1090 ft off a takeoff over a 50-ft obstacle (flaps up, 12500 lb, SL/ISA). In cruise, the enhanced King Air can fly 14 kts faster at 33,000 ft and reduce the time to reach that altitude by 12 minutes.

When landing, the aircraft uses 690 ft less runway over the same theoretical 50-ft obstacle, and approaches 9 kts slower than its factory counterpart. One of the most impressive statistics is a 2920-ft reduction in accelerate-go distance.

Blackhawk Aerospace

The Waco TX company has also jumped on the King Air bandwagon by addressing the powerplant itself. The company maintains that, in lieu of spending money to overhaul a factory engine, it makes more financial sense to spend a little more to get something brand new with better performance.

This is based on the adage that you’ll recoup your costs through better performance and efficiency over the long run. Blackhawk offers its proprietary XP Engine Upgrade for King Air 90/200/300/350/350ER/350NR turboprops.

For purposes of comparison and for consistency with the 200 model previously discussed, Blackhawk sells 3 new engine options – the XP42, XP52, and XP61. The nomenclature corresponds to the model of Pratt & Whitney PT6A you’ll receive, eg, PT6A-42.

The XP52 is advertised as “power for the right price” and touts a 27-kt improvement in speed and a 31% increase in available horsepower at cruise altitude over stock factory engines. More power equates to better takeoff performance, increased climb capability, and better density altitude capability.

Blackhawk uses 100,000 miles flown per year as a metric to define the cost saving associated with buying the XP instead of a stock engine. The company figures that, by saving roughly 45¢ per mile, an owner can bank on annual savings of roughly $45,017.

Then there’s the resale value. The Blackhawk conversion on a King Air is akin to a Colemill Panther conversion on a Piper Navajo (350-hp turbocharged engines, winglets, and Q-tip props) – it commands a premium on the pre-owned aircraft market.

Although Blackhawk is known mostly for its engines, it also offers its Phoenix program, which equates to a complete refurbishment. In addition to 2 brand-new engines, a Phoenix upgrade comes with new or freshly overhauled propellers, a recent phase 1–4 annual inspection, new paint, a new interior, and a glass cockpit.

Buyers can even choose which glass cockpit they want from a list of 4 – Collins Pro Line 21, Garmin G1000 avionics suite, Dual Garmin G600 TXi, or BendixKing Aerovue. The final product is a highly-customized King Air with enhanced performance that has essentially been rebuilt from the ground up.

The Nextant 400XTi is a completely renovated Beechjet 400.

Nextant Aerospace

Nextant Aerospace is a relatively recent entry into the King Air retrofit marketplace (launched in 2007 in Cleveland OH). The G90X is a modification of the factory stock King Air 90. In keeping with the entry-level paradigm, Nextant seems to have focused on ease of operation rather than high performance.

The aircraft uses a revolutionary single-power control lever that’s made possible by electronic engine controls and prop governors. It’s not considered pure full authority digital engine control (FADEC), but it uses similar system logic.

In the event of digital failure the condition levers can be used mechanically to control power. Fuel and pressurization systems are simplified to reduce pilot workload, which is also in line with the popular Garmin G1000 avionics suite.

Nextant replaces the stock Pratt & Whitney PT6A-135 engines with GE-H75 powerplants, which operate at higher internal temperatures and pressures. According to published specifications, the G90XT has a max cruise speed of 280 kts and a certified ceiling of 30,000 ft.

Range with 4 pax is 1362 nm. Nextant has also taken on retrofitting legacy business jets, starting with the Beechjet 400. The aircraft itself has gone through many evolutions as manufacturing changed hands over the years.

Nextant’s 90XT turboprop is designed to be flown by owner/operators or pilots stepping up from piston twins.

The same airframe has been called the Mitsubishi MU-300 Diamond, Beechjet 400, Hawker 400, and T-1A Jayhawk trainer. In 2011, Nextant began replacing the engines, avionics, and interior of legacy Beechjet 400s and rebranding them as the Nextant 400XT or XTi. Nextant’s version provides the performance and look of a newer aircraft at a used aircraft price.

The newer engine is the Williams FJ44-3AP, which provides 3052 lb of thrust per side and delivers a maximum cruise speed of 447 kts (or a long-range cruise of 406 kts). Nextant puts the operating cost per hour at $1218.

The standard cockpit is outfitted with the Collins Pro Line 21 featuring ADS-B, WAAS/LPV, TAWS-A, and IFIS electronic charts. Synthetic vision and XM Weather can also be added as options. In addition, in 2018, Nextant began retrofitting Challenger 604 jets with the Collins Pro Line Fusion avionics package.

And the company is currently developing more cabin enhancements, as well as looking at innovations to improve performance.


Changing something that’s been around a long time has inherent risks. Sometimes those risks don’t turn out so well. April 23, 1985 will go down in marketing infamy as the day the Coca-Cola Company changed the formula for Coke after 99 years.

What followed was a financial boondoggle that created so much backlash that the company changed the formula back to the original after 77 days. The niche market of aircraft retrofitting has had the opposite effect.

Modifications to longstanding airframes have been wildly successful, as new technologies and upgrades continue to increase value, improve performance, and enhance safety.

Shannon Forrest is a current line pilot, CRM facilitator, and aviation safety consultant. He has more than 10,000 hrs TT and holds a degree in behavioral psychology.