Potez 631 and 633 were retained for this production program, which first involved 207 twin-engined day-and-night fighters along with 449 daytime light bombers. On 25 March 1938, the order for the Potez 633 was increased to 125 bombers, which were also requested to be three-seaters. The Potez 633 orders were subsequently cancelled, ordering additional Potez 631 aircraft in their place; further orders of the Potez 631 were placed to allow for the speedy withdrawal of the troublesome Potez 630. Between January and June 1940, an average production rate of 100 aircraft per month was maintained. Design The Potez 630 was a twin engine, monoplane, fully metallic three-seater with efficient aerodynamic lines and twin tailfins. The basic design allowed for the type to replace various obsolete aircraft in the French Air Force in a wide range of roles. The long glasshouse housed a crew of three, comprising a pilot, an observer or commander who was carried based upon mission requirements, and a rear gunner who manned a single flexible light machine gun. The Potez 637 featured a glazed gondola located beneath the fuselage for an observer to be carried in the prone position. Some variants, such as the Potez 631 and 633, had a vertical bomb bay located between the two crew members. The 630 was a relatively simple and sound design, requiring an average of 7,500 man-hours to assemble each aircraft. All members of the family (with the possible exception of the Potez 63.11) shared pleasant flying characteristics and were designed to allow for easy maintenance. As a day fighter aircraft, the performance of the Potez 631 C3 was relatively disappointing, due to a low maximum speed and inadequate rate of climb compared with contemporary fighter aircraft. As a night fighter, lack of detection equipment drastically limited their effectiveness. Later models had a heavy armament (12 machine guns for the Potez 63.11). The Potez 63 family, as with the contemporary Fairey Battle and Bristol Blenheim bombers and like many French aircraft of the time, proved vulnerable to Messerschmitt Bf 109s. Their similarity to the Messerschmitt Bf 110, both being equipped with twin engines, twin fins and a long greenhouse canopy, is believed to have resulted in several aircraft being lost to "friendly fire". Operational service Introduction From May 1938, production Potez 630 fighters started to be delivered; the first improved Potez 631 aircraft were received in August that year. Potez