Pacific Coastal Airlines Beechcraft 1900C, C-FPCO, Vancouver International Airport
The original design is known simply as the Beechcraft 1900. It features two "airstair" passenger boarding doors: one near the tail of the aircraft much like the smaller King Airs, and a second at the front just behind the cockpit. It has a small cargo door near the tail for access to the baggage compartment, which is behind the passenger compartment.
It immediately became clear that two airstair doors were redundant on an aircraft holding only 19 passengers. Beechcraft kept the front airstair, but eliminated the aft airstair door, installing an enlarged cargo door in its place. The changed aircraft was renamed 1900C. Other than the redesigned door layout, the early 1900Cs were substantially similar to the original 1900s.
Early 1900Cs series employ a bladder-type fuel tank system in the wings. Later 1900Cs use a "wet wing" fuel system: entire sections of the wing are sealed off for use as fuel tanks. This design change allowed more fuel to be stored, substantially increasing the 1900C's range.
Pacific Coastal Website: http://www.pacific-coastal.com/