The flight-test program is continuing apace for Nextant Aerospace’s Beechjet 400 conversion as it moves closer to certification. The Cleveland-based company paused the testing last month on its first Williams International FJ44-3AP powered 400XT to fly it nonstop from Mojave, Calif., to Atlanta, for an appearance in the static display at the NBAA Convention. It was shown alongside the company’s fully furnished technology demonstrator aircraft, still carrying its original Pratt & Whitney Canada JT15D-5 engines.

The Williams-powered 400XT (the company was required to change the name from 400NXT due to a copyright issue in another industry) made its first flight on September 8. Thus far it has logged approximately 120 hours of flight time, including a September 26 nonstop positioning flight from the company’s headquarters at Cuyahoga County Airport in Cleveland to Mojave–where the testing program is based–which saw the nearly maximum-weight test aircraft reach a cruising altitude of 45,000 feet.

“One of our goals is 2,000 nautical miles [NBAA IFR range],” company president James Miller told AIN. “On that trip, despite the fact that we were doing a lot of tests that had us slowing down and speeding up and climbing and turning, we would have just about hit 2,010 nautical miles, and of course to do that westbound is really significant.” A range of 2,000 nm would represent a 50-percent increase over the range of the base Beechjet 400A or Hawker 400XP.

The company is maintaining a six-days-a-week flight-test schedule with the goal of logging between 250 and 300 hours aloft by year-end, to wrap up the test program on ­schedule. Nex­tant anticipates STC approval soon after. “We’re expecting certification in the first quarter of 2011,” said Miller.  

According to Nextant, the remanufactured aircraft is meeting or exceeding all performance specifications, and has already demonstrated some design im­provements. The company believes that moving the engines three inches out from the fuselage and changing the angle of the engine exhaust nozzle has eliminated the shockwave that occurs in the choke point ­between the engine and fuselage, reducing noise, vibration and drag while improving fuel efficiency. The rebuild also involved increasing the size of the pylon by approximately 50 percent, contributing to lift. “We think we’ve altered the landing characteristics in a positive way,” said Miller. “It doesn’t bleed speed quite as abruptly as the Beechjet does at any given airspeed.”

Another handling improvement that has been observed in the flight testing stems from the Williams engines’ reduced residual thrust. While the original powerplants produced considerable thrust when idling, the FJ44s do not. “Extra residual thrust is like having your foot on the accelerator and the brake in your car at the same time,” Miller said. “The car wants to go forward and you’re using a lot of brake to hold it back. With the Williams engines, if you bring them back to idle the airplane will actually stop.”

In addition to the new engines, the 400XT package includes a Rockwell Collins Pro Line 21 avionics suite, for which Nextant received the STC last year. It began construction on its second Williams-powered aircraft at the end of September and expects to complete three of the $3.9 million conversions by next May.

The company claims orders for five of the aircraft, and Miller expects to have all six bays in the company’s facility filled by early 2012. By then, it would have used up its current supply of six airframes, most of which came from the fleet of related company Flight Options. The fractional provider, which still has 60 400XPs in its fleet, plans to convert many of them to 400XTs, even as it acquires Embraer Phenom 300s. Given that supply as well as those available on the market, Nextant feels little pressure in acquiring airframes for future 400XT conversions.