In 2014, Embraer built and tested a , technology demonstrator that was partially made of FML and was based on the central fuselage of its ERJ-145 aircraft. Later, Embraer worked with Arconic (formerly Alcoa) to build a demonstrator for a lower wing skin composed of fiber-metal laminates, which contained sheets of 2524-T3 aluminum alloy and unidirectional plies of glass fiber. Embraer built and tested the wing demonstrator to increase the TRL of the FML manufacturing process so that it can be applied to future structural applications. Lower wing skins on single-aisle aircraft are thicker than fuselage skins, measuring at least thick overall and between thick between the fuselage and the engine mount.