Nextant 400XTi: A Beechjet Made Modern

“There had to be a way of delivering the latest in business jet technology without doing a clean-sheet design,” said Jay Heublein, executive v-p of global sales and marketing for Nextant Aerospace, explaining the reasoning behind the Nextant 400XTi remanufacturing of the Beechjet 400/Hawker 400XP. The hundreds of millions of dollars needed to develop a new jet is a huge barrier, yet a well designed and -built jet has a long service life and could be an ideal platform on which to add new avionics and engine technology as well as aerodynamic tweaking using modern tools such as computational fluid dynamics.

Cleveland-based Nextant was launched in 2007 and is owned by Directional Aviation Capital, which also owns fractional-share operations Flight Options and Flexjet as well as MRO provider Constant Aviation, charter brokerage Sentient Jet, sales company Sojourn Aviation, parts distributor Aerospace Products International and Corporate Wings FBOs. Kenn Ricci founded many of these companies and is principal of Directional Aviation Capital.

Nextant selected the Beechjet, Heublein said, because “it’s the most robust light jet. And we bring technology where it makes sense, delivering everything good about a new aircraft but at 50 cents on the dollar.” Nextant sister company Flight Options has many years experience operating the Beechjet/Hawker 400. “We know everything good and bad about it,” he said.

The 400XTi is essentially a Beechjet 400/Hawker 400A/XP with new Fadec-controlled 3,050-pound-thrust Williams International FJ44-3AP engines replacing the original 2,965-pound Pratt & Whitney Canada JT15D-5Rs, aerodynamic improvements to the nacelles and pylons, a new Rockwell Collins Pro Line 21 flight deck, fresh interior and other enhancements. The jets undergo 60 engineering changes, replacement of more than 40 time-controlled components, compliance with A-, B-, C- and D-check inspections as well as compliance with all FAA airworthiness directives and applicable manufacturer service bulletins during a 6,000-man-hour renewal/overhaul process. The resulting remanufactured 400XTi carries a two-year tip-to-tail warranty (three for the engines), which can be extended to five years as an option.

The first remanufactured version was the 400XT, but last year Nextant introduced the 400XTi, with an improved and more spacious composite cabin shell that takes full advantage of unused space in the fuselage, a new noise insulation package, Nextant-designed winglets, Luma Technologies LED warning panels and a Mid-Continent Instruments LCD standby attitude module and True Blue Power MD835 lithium-ion backup battery units. The MD835s eliminate a 90-day inspection interval for the jet’s original lead-acid backup batteries.

So far, Nextant has converted more than 40 Beechjet/Hawker 400s and delivered them to owners in eight countries since certification of the upgrades in 2011. Flight Options has ordered forty 400XTi conversions, and charter provider Travel Management Company is upgrading its entire fleet of 50 Beechjet/Hawker 400s. Nextant’s backlog represents a quarter of the available fleet of about 600 jets, according to Heublein. There are also another 180 Air Force T-1A Jayhawks (Beechjet 400s) that could be converted, if the Air Force were to select the 400XTi upgrade instead of buying a new jet for its Air Education and Training Command bases.

The Nextant 400XTi sells for $5.15 million. The airframe is valued at $995,000, so that would be deducted from the price if an owner brought a Beechjet/Hawker 400 for conversion. The performance improvements include a 50-percent range extension, 30 percent lower operating costs and 20 to 25 percent less fuel burn. “Hot and high performance is enormously improved,” said Heublein.

Multiple Modifications

Although Textron Aviation’s Hawker Beechcraft Services has developed the Beechjet/Hawker 400XPR upgrade program, it differs in one major aspect from the Nextant version. The XPR is powered by Williams International FJ44-4A-32 engines, which at 3,600 pounds of thrust (flat-rated to 3,200 at ISA +17 deg C) are more powerful but about 100 pounds heavier than the 3,502-pound FJ44-3APs (flat-rated to 3,050 pounds at ISA +7 deg C) in the Nextant 400XTi. The first 400XPR delivery is expected in the fourth quarter, following winglet and engine certification (the Pro Line 21 upgrade is already certified), according to Textron Aviation.

Heublein said that Nextant engineers considered the heavier FJ44-4A-32 engine but decided that it made more sense to use the -3APs and burn less fuel. The advantage of the larger engines is better hot-and-high performance, he conceded. But the jet itself can’t fly faster than its limiting Mach .785 Mmo, and making it able to weigh more at takeoff would involve significant changes to the landing gear and wing attach structure, changes that the company determined were not worth pursuing.

The new composite cabin shell by Jeff Bonner R&D takes advantage of space within the fuselage structure that the existing interior didn’t use, and it adds three inches of width and 2.5 inches of height. N2Aero insulation reduces cabin noise by nine decibels, to 66 dB.

Three interior layouts are available, and a typical choice is the forward divan opposite the galley, then a four-club configuration, with seats for up to eight passengers (including the belted lavatory). Also offering eight seats is the four-club layout with two forward-facing seats aft and one seat up forward opposite the galley. This layout provides less legroom in the club seating area, however. A six-seat interior puts the galley on the right side of the cabin and includes the spacious four-club seating area, one seat opposite the galley and forward of the cabin door, plus the lavatory seat. Passenger seats were redesigned by Nextant engineers and are mechanically rebuilt and recovered. The two aft-facing seats in the club-seating area fold flat, and the divan can be extended outward to provide a larger sleeping surface.

The updated interior is fitted with a Rockwell Collins Venue cabin management system (CMS) with Airshow moving map, Apple iOS device control of the CMS, LED lighting and a new galley with a Nespresso machine and a new work surface. Optional features include Aircell Gogo Business Aviation Axxess (air-to-ground telecom and SwiftBroadband satcom) and 110-/220-volt power outlets. The lavatory bulkhead is moved six inches forward, and this helps provide more interior space for luggage (an additional 20 cu ft), as one of the Beechjet’s Achilles heels is the small 26-cu-ft external baggage capacity.

On the outside, the most prominent change is the new winglets with embedded LED lights. Most of the upgraded jets were equipped with aluminum winglets, but soon, if not already, the 400XTi will have new carbon-fiber winglets that are raked back farther and shave 24 pounds off the empty weight. The new winglets bolt onto the existing structure and will be provided as a kit to owners with the old winglets.

The new nacelles housing the Williams engines and the larger pylons are the fruit of computational fluid dynamics analysis that showed excessive drag due to a supersonic shockwave in the area between the nacelles and the fuselage. The pylons now have twice the surface area, and the redesign eliminated the drag problem.

To help improve maintenance access to the nose gear and other areas, Nextant added access panels so mechanics don’t need to remove dozens of fasteners for routine maintenance tasks. Further adding to future reliability is a completely new primary wiring harness, built by Nextant technicians on the company’s own looms. The new wiring meets the latest FAA electrical wiring interconnection system regulations.

The heavy remanufacturing and maintenance tasks take about eight to 10 weeks, during which the Beechjet/Hawker 400 is completely stripped down. All life-limited components are replaced, landing gear is overhauled, the entire structure is inspected and any repairs are completed. Typically, the horizontal stabilizer has cracked ribs, induced by an oscillation caused by the thrust reversers. Nextant technicians install thicker ribs in a special jig built in-house.

The engine mount beam that runs across the aft fuselage is another weak area, and Nextant engineers redesigned the beam with added doublers to make it stronger but maintain the same geometry so that it would meet the latest regulatory stress load requirements without requiring modification of the adjacent structure. Nextant also replaces the engine mount with a much stronger one-piece milled unit made of stainless steel alloy.

After the major maintenance and modification phase, including avionics upgrades, the jet is moved outside for engine runs and flight-testing, then the exterior is painted and the interior installed. The final flight-test takes place about 16 to 17 weeks after the jet rolls into the Nextant facility. One sure way to spot a Nextant modified Beechjet/Hawker 400 is the new supplemental data plate mounted next to the old one on the aft fuselage.

Flying Options

For pilots, the biggest visible change is the flight deck, where the old CRT-based Rockwell Collins Pro Line 4 avionics are replaced with a modern Pro Line 21 suite. The base system in the 400XTi includes two PFDs and two MFDs in portrait orientation, which provides one PFD and one MFD for each pilot to control. Dual Collins FMS 6100s are mounted on the angled portion of the console between the seats. All other avionics are new, including dual solid-state AHRS, autopilot, Waas LPV GPS 4000S, com and nav, ADF, DME, transponders, radar altimeter, weather radar, Taws, Tcas II, DBU 5010E database loader, 406-MHz ELT and the Mid-Continent standby attitude module. The eyebrow warning lights now use LEDs instead of fussy incandescent bulbs. Engine instruments are all hosted on the Rockwell Collins MFDs, and if an MFD fails the engine indications migrate to the respective PFD.

Avionics options include international features such as a digital flight data recorder and Taws A. The SiriusXM weather option can be displayed on either pilot’s MFD. The base system includes one version of the Rockwell Collins IFIS electronic charts system, and a second IFIS is optional. The Pro Line 21 synthetic vision system is expected to be certified this year, and Nextant is also planning to add a Safe Flight autothrottle system as an option.

Where the 400XTi mod truly shines, however, is the greatly improved performance of the new Williams engines. Nextant chief pilot Nathan Marker, who did all of the 400XT primary flight-testing, and Nextant pilot Bryan Bellas demonstrated the 400XTi’s capabilities to me on a foggy June day from the company headquarters at Cleveland’s Cuyahoga County Airport. I spent some time flying the 400XTi at altitude and it is a well integrated jet, with excellent handling characteristics and a simplified, uncluttered and modern-looking cockpit.

The Williams engines are responsive, and during the takeoff roll accelerated the 400XTi strongly and, at a takeoff weight of 13,800 pounds–2,500 below the 16,300-pound mtow–pushed the 400XTi up to 40,000 feet in just 15 minutes. Temperatures during our flight started out higher than ISA, but at FL400 dropped to ISA. We were still climbing at more than 2,000 fpm at 30,000 feet. Takeoff field length on that warm day, about ISA+15 on the ground, was about 3,100 feet.

At FL410 we set the power for long-range cruise, which delivers Mach .70 and 392 ktas while burning 730 pph total. Pushing up the power to maximum continuous thrust raised the fuel flow to 1,040 pph, but in those conditions the airspeed would exceed the Mmo, so we dialed back the power and settled at the normal cruise of Mach .73 and 447 ktas, which brought the fuel flow down to about 1,000 pph.

The 400XTi can fly about five hours after reaching FL400 to FL410 at long-range cruise speed, according to Marker. The performance numbers in the flight manual supplement show that at a weight of 14,000 pounds, a climb to FL410 on an ISA day would consume 458 pounds of fuel. Climbing to FL450 in the same conditions should take 23 minutes and 578 pounds of fuel.

The stock Hawker 400XP can fly 1,464 nm with two pilots and four passengers (NBAA IFR reserves, 100-nm alternate). Under the same conditions, the 400XTi can fly more than 2,000 nm. Fuel capacity is 4,912 pounds. Typical BOW for a 400XTi is between 10,750 and 10,850 pounds, Marker said, depending on the options and interior configuration. These numbers are lower than the typical 10,985-pound BOW of a Hawker 400XP.

The Nextant 400XTi represents a significant step toward near-production-line remanufacturing of airframes that have a lot of useful remaining life. What makes Nextant founder Ricci’s vision tangible with this project is that the Beechjet 400/Hawker 400XP was primed for re-engining with quieter, more powerful and more efficient Williams engines and upgrading the avionics. Indeed, Beechcraft’s own 400XPR program underscores the value in these airframes, not to mention the former Hawker Beechcraft’s one-time plan to put a Hawker 450 powered by Williams engines into production. Other jets may be likely candidates for the remanufacturing treatment, and there’s no doubt that Ricci and crew are busy pondering various options while preparing the next Nextant project for certification, the G90XT remanufactured Beechcraft King Air C90.