Sierra Industries and Clifford Development have formed a joint venture called NewJETz to develop a Williams International FJ44-4 engine retrofit program. The 3,600-pound-thrust engine retrofit will power legacy Cessna Citation 550 and 560 series jets, including the Citation V, Bravo, Ultra and Encore. The new modification is called eVolution, and NewJETz will also offer owners of these aircraft avionics and other upgrades.

The same engine is being used for the Hawker 400XPr retrofit program, which is a joint venture between Sierra and Hawker Beechcraft. In fact, Sierra brought the 400XPr development aircraft to the NBAA Convention this week.

First flight of the 400XPr, powered by Williams FJ44-4A-32 turbofans, took place on May 3 and “demonstrated some amazing performance,” according to Sierra’s Jim Gerrish. “They pegged 6,000-fpm climb rate at one point,” he said. After takeoff, the 400XPr climbed to 5,000 feet in one minute and eventually reached 14,000 feet and 320 knots during the maiden flight. “This thing just performed flawlessly,” the company said after the flight.