Learjet 60 Business JetGates Bombardier Learjet 60 airplane model. The improved Learjet 60 first flew in its basic definitive form in June 1991 (the modified Learjet 55 prototype earlier served as a proof of concept aircraft for the 60 with` Garrett engines). It differs from the 55 in having a 1. 09m (43in) fuselage stretch and new Pratt Whitney Canada PW305 turbofans. Certification of the 60 was awarded in January 1993, with first deliveries following shortly afterwards.