High Quality Content by WIKIPEDIA articles! The LearAvia Lear Fan 2100 turboprop was made of lightweight composite materials instead of the more usual aluminum alloy. It also featured an innovative pusher design, in which two aircraft engines powered a single constant-speed three- or four-bladed propeller at the rear of the aircraft. A purpose-built gearbox allowed either or both Pratt Whitney of Canada PT6B free-shaft turbines to supply power via two driveshafts. The intent of the design was to provide the safety of multi-engine reliability, combined with single-engine handling in case of failure of one of the engines.