[4] The spar, which was located at one third of the chord from the leading edge, had wide duralumin flanges, the width and thickness of which diminished along the span in proportion to the variation of the bending movements.

[5] These flanges are joined at different points by special steel and duralumin fittings that could transmit stresses of up to 1,000,000 kg (220,460 lb.).

The leading edge comprised box formers with longitudinal stringers and an auxiliary spar at the extreme front.

[5] Each aileron was divided into three sections in order to tolerate deformations of the wing without exerting too much force on the aircraft's rigid flight controls.

[5] The positioning of the wing spar between the cockpit and the passenger cabin made it possible for the latter to make use of the full height of the fuselage, which led to it having a slightly rounded ceiling.

The cabin was typically fitted with two rows of four comfortable chairs, each having adjustable backs and transformable into recliners or even into couches.

The engine bearers, which comprised chrome-nickel tubing with large ribs that reinforced the welded joints, were mounted on noise-dampening blocks.

[8] This fork guided a pair of Liessier hydraulic brakes that were balanced and terminated by two bearings on which the axle is mounted.

[9] In several respects, the aircraft proved to be capable of greater performance than the requirement had stipulated, such as achieving a cruising speed (while at 55% of engine power) of 250 km/h (155.3 mi./hr.)

The prototype was named Émeraude ("Emerald" in French) and carried out demonstration flights around European capitals.

Émeraude gained a world class record on 7 September 1933 when it flew a 1,000-kilometer (621-mile) course with a useful load of 2,000 kilograms (4,410 pounds) at an average speed of 159.56 km/h (99.1 mph).

Despite the loss of the prototype during a proving flight in an accident, Air France decided to order three aircraft of an improved version, designated the D.333.

However, on the return flight, when only 400 km (250 mi) from its destination, Le Bourget airport, Émeraude struck a hill near Corbigny in a violent snowstorm and was destroyed.