 In 1991, four Saab 340Bs arrived at the commuter division to replace the Short 360 aircraft.By 1992, Aer Lingus's entire original 737-200 fleet had been replaced and it was now the first carrier in the world operating all three versions of the second-generation 737.These were the −300, −400 and −500 series, although the −300 did not stay long in Aer Lingus service.