On a warm morning in the Texas hill country about 70 miles west of San Antonio, Mark Huffstutler pushed the thrust levers forward and launched a re-engined Hawker Beechcraft 400XPR into the cloudy skies. The first flight on May 3 was the culmination of 14 months of engineering and mechanical work, much of it done by Huffstutler’s Sierra Industries, a modification shop located at Garner Field Airport in Uvalde, Texas. The Hawker 400XPR is the second major modification program that Hawker Beechcraft Global Customer Support has launched; the first was the 800XPR upgrade. These represent a key strategy by Hawker Beechcraft, to bring new value to airframes that are going to last a long time and can help the company earn new sources of revenue. (A competing Beechjet/Hawker 400 Williams engine and avionics upgrade is available from Nextant Aerospace.)

The 400XPR’s main upgrade swaps the original 3,000-pound-thrust Pratt & Whitney Canada JT15D engines for Fadec-controlled 3,600-pound Williams International FJ44-4A-32s (flat-rated to 3,200 pounds). The two other 400XPR upgrades are Rockwell Collins Pro Line 21 avionics and Hawker Beechcraft-designed winglets, and each of the mods can be purchased individually or in combination.

Sierra Industries and its Swat engineering division in San Antonio provided manufacturing and engineering integration and did the mod work on both the 400XPR and the 800XPR. The 800XPR package offers winglets, Pro Line 21 avionics and replacement of the original Honeywell TFE731-5BRs with -50s.

XOJet is now operating seven 800XPRs that used to be NetJets airplanes, and plans call for the charter operator to add five more of the modified Hawkers. “We’re really happy with the airplane,” said Dave Cox, XOJet senior v-p and COO. “Performance-wise it’s been great. The customers really like it, and it’s been a great addition to the fleet.” XOJet’s 800XPRs have the engine and winglet mods, but retained the original Honeywell avionics.

The 400XPR that flew on May 3 had just the engine upgrade; another 400XP was in a Sierra Industries hangar getting the final touch on the Pro Line 21 upgrade, while winglets are currently being installed and will fly in about another six weeks. The avionics upgrade is certified and the winglets should be certified in August, followed by the engine mod in September. Sierra and Hawker Beechcraft incorporated other reliability improvements, including a nose-gear redesign that allows mechanics to service the nose strut’s hydraulic fluid without having to remove the strut; a bleed-air redesign to eliminate an AD; and a new starter generator that will operate for 1,500 hours instead of the current 500. Huffstutler said he’d like to add a single-point refueling system for the 400XP. “These airplanes last for 30 or 40 years. We can provide the same performance [as a new airplane] at half to a third of the price.”

Huffstutler prefers working with Hawker Beechcraft on the 400XPR instead of trying to do the 400XPR engine mod independently. “If we do it in cooperation with the manufacturer, we have access to its data and can get a lot more performance [from the modification],” he explained. Hawker Beechcraft’s change of attitude in recent years has led to its working with a variety of aftermarket modifiers. “I consider [Hawker Beechcraft] to be a leader in the industry with adoption of modifications,” he said. “I hope we’ll join with Hawker Beechcraft to develop more new products.”

There are 604 Beechjets/400XPs eligible for the 400XPR upgrades. Sierra Industries is building the modification kits and Hawker Beechcraft Services at Fulton County Airport in Atlanta will do the installations.

“This thing just performed flawlessly,” said Huffstutler after the flight. He flew left seat with Hawker Beechcraft test pilot Dave Newton in the right seat. The flight-test 400XPR was not yet air conditioned or pressurized. After takeoff, the 400XPR climbed to 5,000 feet in one minute and reached 14,000 feet and 320 knots. Other testing done during the first flight included throttle transients and flight at minimum speed. Before landing, Huffstutler flew two low passes along Garner’s Runway 15-33, accompanied by his son Conrad flying a P-51 Mustang as wingman.