The Beech C-45 Expeditor is one of several aircraft based on the Model 18 Twin Beech. Beech manufactured over 5,000 aircraft during World War II for the U.S. and several foreign governments. Other variants of this aircraft were the AT-11 Kansan bombardier and gunnery trainer, the AT-7 Navigator navigation trainer, and the Navy's SNB-1 and SNB-2 trainers and JRB utility transport.
In service with the RCAF, the Expeditor was known by many nicknames such as Twin Harvard, Wichita Wobbler, Exploder, and Bug Smasher and its many roles included multi-engine training for pilots, navigators and radio operators; liason; VIP transport; and search and rescue. Unification of the Canadian Armed Foces took place in 1968 with only 53 Expeditors remaining of the total of 366 once listed as on strength and these were all due for retirement during 1970 -72 along with the Dakota fleet.
The C-45 earned the nickname "Bug Smasher" and served as a small transport/liaison aircraft. The aircraft on display at Castle Air Museum served with the Navy at the San Diego Naval Air Station. In 1951 it was part of a program to rebuild AT-7/AT-11/SNB aircraft to C-45 configuration. After military service, it was used as a civilian aircraft by the Department of Agriculture.