<hi style=afpcap>Boeing built a total of 75 model 247s prior to the US entering World War Two, with 27 being drafted into the Army in 1942 as the C-73. The aircraft featured a small airline cabin, with a fairly narrow access door which prevented their use as troop carriers or to transport heavy cargo, so they were relegated to crew ferrying and training duties. The Army replaced their 550 h.p. Pratt and Whitney Wasp engines with 600 h.p. R-1340-AN-1 powerplants offering a slight increase in performance.</hi>
<hi style=afpcap>The second of the two Advanced Medium STOL Transport (AMST) aircraft was the McDonnell Douglas YC-15 which was funded in 1972 to compete against the Boeing YC-14. The McDonnell Douglas proposal was powered by four JT8D-17 turbofan engines. with blown flaps to aid lift and manoeuvrability. Both types featured a high wing coupled to a fuselage designed to accomodate specific cargos such as armour and bulky loads. Despite a large financial investment by both manufacturers, the programme was abandoned due to cost over runs. </hi>
