In 1936 the well-established
Potez company became part of the Société Nationale de Constructions Aéronautique du Nord (
S.N.C.A.N.), under the Law for the Nationalisation of Military Industries. In 1937 they produced their first four-engined aircraft, the Type 661. This was a commercial machine with seating for up to twelve passengers. It was a low wing cantilever, almost all-metal monoplane. The wing tapered with a nearly straight trailing edge that carried outboard balanced ailerons and split trailing edge flaps over the whole of the centre section. The four 220 hp (164 kW)
Renault 6Q inverted inline engines were conventionally mounted of the front wing spar and drove variable-pitch twin-bladed propellers. The fuselage was a metal monocoque, with a port side passenger door aft of six windows on each side, one per seat. Though the standard seat arrangement was for twelve, two seats could be removed to allow the installation of chaises-longues for longer flights. The pilots' cabin was enclosed, with side by side dual control seating. The tail unit carried twin vertical
endplate fins, slightly oval on a tailplane that had strong dihedral. The balanced rudders and elevators were metal structures with the only fabric covering used on the aircraft. The elevators carried trim tabs. There was a small tailwheel, the main undercarriage retracting into the inner engine nacelles. ==Operational history==