At last month’s NBAA Convention, Spirit Wing Aviation of Edmond, Okla., announced that it will begin producing its “virtually new” Spirit-Lear early next year. The company said the $2.2 million SpiritLear–a re-engined Learjet 25–will be priced lower than any other airplane offering its combination of speed, range and passenger capacity. It will cruise at Mach 0.81 at up to FL450 while offering operating economies that Spirit Wing claims are 20 to 30 percent lower than those of the competition.
The SpiritLear employs the no-life-limit airframe of the Learjet 25 and replaces the original GE CJ610 turbojets with Williams FJ44-2C turbofans; revamps the pressurization, hydraulic, electrical and fuel systems; and updates the avionics to meet RVSM requirements.
Calvin Burgess, president of Spirit Wing Aviation, last month said the aircraft is now in full FAA certification testing, and an STC for the modifications is expected in the first or second quarter of next year. The company will begin modifications at three authorized service locations–West Star Aviation in Grand Junction, Colo., Banyan Aviation Services in Fort Lauderdale, Fla., and General Dynamics Flight and Aerospace Research in Niagara Falls, N.Y.–immediately upon receipt of the STC.
Spirit Wing’s only modification to the airframe consists of damage-tolerant design improvements to the engine beams and associated structure and the rebalancing of controls as required. “Based on the Learjet’s original design and the inspection and preparation process we perform on the aircraft before beginning the modification, the age of the airframe is not an issue,” he noted. “In fact, the SpiritLear has an expected life of up to 80,000 hours, much longer than that of more contemporary designs.”
Because the Williams engines are dimensionally different from the CJ610s originally installed on the 20-series Learjets, Spirit Wing Aviation has modified the SpiritLear’s front engine beam and installed a new rear engine support beam, effectively moving the engine nacelle aft 16 inches and outboard four inches. An added feature of the modification is a dramatic reduction in drag, which results from the repositioned engine, providing more engine-induced airflow. This improves lift over the critical inboard portion of the wing, which in turn reduces the angle of attack, resulting in lower fuel burn and reduced power requirements for high-speed cruise.
The SpiritLear’s FJ44-2Cs are modified to allow their thrust to be reduced to 100 pounds at idle, resulting in shorter landing distances. And the incorporation of the FJ44-3 power turbine sections into the SpiritLear’s engines ensures that more thrust is available under hot-and-high conditions. Additionally, the Williams powerplants extend the aircraft’s range by approximately 70 percent.