The Potez 840 was an all-metal cantilever-wing monoplane with a retractable tricycle landing gear. It had a crew of three and a cabin for 18 passengers. It was powered by four 440 shp (328 kW)
Turbomeca Astazou II
turboprop engines. The prototype first flew on 29 April 1961; a second aircraft flew in June 1962 and had more powerful 600 shp (447 kW)
Turbomeca Astazou XII engines. The second prototype carried out a sales tour of North America and it was planned to build a batch of 25 aircraft for Chicago-based Turbo Flight Inc. but only two more prototype aircraft were built, one for static testing. The next two aircraft were designated the
Potez 841 and were powered by 550 shp (417 kW)
Pratt & Whitney Canada PT6A-6 turboprop engines. Another two modified Astazou-powered aircraft were produced, one in 1965 and one in 1967. It was intended to build Potez 840s in a factory at
Baldonnel Aerodrome in the
Republic of Ireland with financial aid from the
Government of Ireland but this factory was closed in 1968 without completing a single aircraft. The former Potez factory at Baldonnel became an engine maintenance facility for the German airline
Lufthansa with the factory finally closing in 2013. ==Service==