In 1937, the French Conseil Supérieur de l'Air decided that domestic aircraft manufacturing capacity could not, in the event of war, equip the Armée de l'Air with fighters quickly enough.
The Dutch manufacturer Koolhoven was contracted to design a cheap, easily built, high-performance fighter, that could be built and serviced with French-supplied engines and other components.
According to some sources, the Koolhoven fighter was intended primarily for fighter units based in French colonies.

The prototype Koolhoven Model 1166, designed by Erich Schatzki, flew for the first time on 17 July 1938.
The structure of the fuselage consisted of welded steel tubing covered with sheet metal (front part) and fabric (aft); the wing had 2 wooden box spar members and ribs, with a bakelite stressed skin covering.
Aerodynamically balanced split flaps on the wing trailing edges ensure a lower landing speed.
The oleo-pneumatic undercarriage retracted inwards with the wheels housed in the lower fuselage faired into the lower engine cowling by small doors.
The empennage is built up from wood and control surfaces are metal framed with fabric covering.

In January 1939, the Armée de l'Air placed an order for 50 aircraft, to be powered by Gnome-Rhône 14N engines.

Due to the unavailability of Gnome-Rhône engines and French instruments, just 17 aircraft – six F.K.58s and 11 F.K.58As – were completed at the Koolhoven works, with Dutch supplied engines and instruments – and delivered to the Armée de l'Air.
Production was transferred to Nevers, where the aircraft were re-built with French components and the extraneous parts were returned to the Netherlands.
However, only one more F.K.58 was produced from scratch at Nevèrs.

In July 1939, the Dutch government placed an order on behalf of the Luchtvaart Afdeling (Netherlands Army Aviation Corps) for 36 F.K.58 variants, powered by Bristol Taurus engines.
As the  British government restricted exports of the Taurus, they were to be replaced by Dutch stocks of the Bristol Mercury VIII (as used by the Dutch Fokker D.21 and Fokker G.1).
The lower output of the Mercury, relative to the Taurus, would have reduced top speed to some 480 km/h (300 mph; 260 kn).

The F.K.58s comprising the Dutch order were in various stages of construction when they were destroyed by a German air raid on the Koolhoven factory in May 1940.

Had the Armée de l'Air received its full order of 50 aircraft, before for the Battle of France, it is unlikely that they would have changed the outcome.
The F.K.58s that became operational were regarded as superior to the Morane-Saulnier M.S.406, comparable to the Bloch MB.151,, but inferior to the Dewoitine D.520 and the latest German fighters.
In 1937, the French Conseil Supérieur de l'Air decided that domestic aircraft manufacturing capacity could not, in the event of war, equip the Armée de l'Air with fighters quickly enough. The Dutch manufacturer Koolhoven was contracted to design a cheap, easily built, high-performance fighter, that could be built and serviced with French-supplied engines and other components. According to some sources, the Koolhoven fighter was intended primarily for fighter units based in French colonies.
The prototype Koolhoven Model 1166, designed by Erich Schatzki, flew for the first time on 17 July 1938. The structure of the fuselage consisted of welded steel tubing covered with sheet metal (front part) and fabric (aft); the wing had 2 wooden box spar members and ribs, with a bakelite stressed skin covering. Aerodynamically balanced split flaps on the wing trailing edges ensure a lower landing speed. The oleo-pneumatic undercarriage retracted inwards with the wheels housed in the lower fuselage faired into the lower engine cowling by small doors. The empennage is built up from wood and control surfaces are metal framed with fabric covering.
In January 1939, the Armée de l'Air placed an order for 50 aircraft, to be powered by Gnome-Rhône 14N engines.
Due to the unavailability of Gnome-Rhône engines and French instruments, just 17 aircraft – six F.K.58s and 11 F.K.58As – were completed at the Koolhoven works, with Dutch supplied engines and instruments – and delivered to the Armée de l'Air. Production was transferred to Nevers, where the aircraft were re-built with French components and the extraneous parts were returned to the Netherlands. However, only one more F.K.58 was produced from scratch at Nevèrs.
In July 1939, the Dutch government placed an order on behalf of the Luchtvaart Afdeling (Netherlands Army Aviation Corps) for 36 F.K.58 variants, powered by Bristol Taurus engines. As the  British government restricted exports of the Taurus, they were to be replaced by Dutch stocks of the Bristol Mercury VIII (as used by the Dutch Fokker D.21 and Fokker G.1). The lower output of the Mercury, relative to the Taurus, would have reduced top speed to some 480 km/h (300 mph; 260 kn).
The F.K.58s comprising the Dutch order were in various stages of construction when they were destroyed by a German air raid on the Koolhoven factory in May 1940.
Had the Armée de l'Air received its full order of 50 aircraft, before for the Battle of France, it is unlikely that they would have changed the outcome. The F.K.58s that became operational were regarded as superior to the Morane-Saulnier M.S.406, comparable to the Bloch MB.151,, but inferior to the Dewoitine D.520 and the latest German fighters.
Koolhoven F.K.58