conducted its maiden flight from Méaulte, Picardy. Initially, the prototype was equipped with an experimental feature in the form of a braced horizontal stabilizer that incorporated no dihedral. On 6 May 1936, the prototype suffered some damage due to a hard landing following the mid-air loss of a propeller blade. On 3 August 1936, after receiving repairs, the Potez 630-01 was transferred to Villacoublay Air Base, Île-de-France; it was soon refitted with an alternative tail arrangement similar to later production aircraft and long-stroke landing gear. On 20 November 1936, flight testing of the prototype resumed; it was shortly thereafter delivered to the Centre d'Essais de Matériels Aériens (CEMA) for official tests. The original engines of the Potez 630-01 were progressively replaced with improved models of Hispano-Suiza engine, gradually increasing thrust to reach 700 hp on takeoff. At its maximum takeoff weight of 3,850 kg, the prototype was capable of a maximum speed of 460 km/h and a maximum range of 1,300 km when flown at an economical cruising speed of 300 km/h. In March 1937, the second prototype, designated Potez 630-02, performed its maiden flight from Méaulte. The Potez 631-01 was damaged after a landing with its landing gear not being locked into the down position; after repairs, it was handed over to CEMA for official trials in November 1937. Production On 23 December 1936, the Société nationale des constructions aéronautiques du Nord (SNCAN) was officially formed, grouping together five French aircraft factories; further amalgamations into SNCAN soon took place, including Potez in early 1937. Shortly following its establishment, SNCAN received a provisional order letter for ten experimental aircraft; four of these were derived from the Potez 630, three from the Potez 631 (one being the existing 631-01 prototype), two Potez 633 light bombers and one Potez 637 aerial reconnaissance aircraft. This was promptly confirmed by a contract, under which one Potez 633 was replaced by a single Potez 637 low level ground attack aircraft. In June 1937, an order for an initial production batch of 10 two-seat and 30 three-seat Potez 631 day fighters was received, the first five of which were to be delivered by February 1938. As large-scale manufacturing of the Gnome-Rhône 14M engines had yet to be achieved and thus was not able to reach the desired production rate of the Potez 630, an additional order was placed for 80 aircraft powered by the alternative Hispano-Suiza