Convair CV-640

The Convair CV-640 was a turboprop conversion of the later Convairliner models, made from a Convair CV-340 or CV-440 by fitting Rolls-Royce Dart turboprop engines with four-blade propellers in place of the piston engines and their three-blade propellers. It paralleled the CV-600, which gave the same Dart engines to the earlier CV-240, and as with the CV-600 the conversions were performed by Convair rather than by an outside company. The type was still flying long after the piston Convairliners had left main-line service: in 2012 a total of seven Convair CV-640 aircraft remained in airline service, one with Rhoades Aviation and six with C&M Airways. It sits beside the Napier Eland CV-540 and the Allison-powered CV-580 among the turboprop re-engining programmes applied to the Convairliner family.