The Nord 3400 was designed to meet a French Army requirement for a two-seat observation aircraft with a secondary casualty-evacuation role. The 3400 is a braced-high-wing monoplane with a fixed tailwheel landing gear and an enclosed cabin with tandem seating for a pilot and observer. The prototype F-MBTD first flew on 20 January 1958 powered by a 240hp (179kW) Potez 4D-30 engine. A second prototype with an increased wing area followed and it was powered by a 260 hp (194 kW) Potez 4D-34 engine. A production batch of 150 was ordered by the French Army in the same configuration as the second prototype.