It quickly became clear that having two airstair doors on an aircraft holding only 19 passengers was excessive. In creating the 1900C, Beechcraft kept the front airstair, but eliminated the aft airstair door, installing an enlarged cargo door in its place. Other than the redesigned door layout, the early 1900Cs were substantially similar to the original 1900s. These were assigned serial numbers starting with the letters UB. A total of 74 UB version were built, many of which remain in service.