The designation Douglas XC-112 was given to two different aircraft, one a proposed pressurized version of the C-54 and the other the first military DC-6. The first of these aircraft was to have been powered by four Pratt & Whitney R-2800-22W engines, but work on the design was abandoned in favour of a transport aircraft based on the DC-6.
This second XC-112 made its maiden flight on 15 February 1946. It was powered by four 2,100hp Pratt & Whitney R-2800-34 engines, and made its maiden flight on 15 February 1946. It remained in USAAF service for long enough to be redesignated as the service test YC-112A, but was soon sold off. It survived for thirty years, before finally being damaged beyond repair on 8 February 1976 after a crash during take-off at Van Nuys Airport, California, having spent the last eight years of its existence being operated by Mercer Airlines. A number of DC-6s were later ordered for the USAF, under the designation C-118, and for the US Navy as the R6D.