In 1992, NASA initiated a program, Advanced General Aviation Transport Experiments (AGATE) to partner with manufacturers and help develop technologies that would revitalize the sagging general aviation industry.

In 1996, Williams joined AGATE's General Aviation Propulsion (GAP) program to develop a fuel-efficient turbofan engine that would be even smaller than the FJ44.

Williams then contracted with Burt Rutan's Scaled Composites to design and build the V-Jet II, considered a Very Light Jet (VLJ), to use as a testbed and technology demonstrator to showcase the new engine.

The V-Jet II was an all-composite structure with a forward-swept wing, a V-tail, each fin of which was mounted on the nacelle of one of the two engines.

The airframe was significantly redesigned as an all-metal structure sporting a T-tail, and the name Eclipse 500.